by Louise Kosta
Chief writer, The Human Ecologist

IAQ factors, one by one

... Outdoor air comes indoors

"Air pollution" is generally considered to be an outdoor air issue-- and so it is. But when outdoor air comes indoors, it becomes part of the indoor environment. It brings with it everything it contained outdoors-- smog, automotive exhaust, industrial fumes, pesticide vapors, nuisance odors from neighborhood activities ranging from smoky barbecue grills to sewage treatment plants, and vapors from outdoor maintenance activities such as road and roof tarring, and structural painting. Outdoors, sunlight, prevailing winds and lack of enclosure cause pollutants to dissipate over a fairly broad area. However, these same pollutants, once they come indoors, are confined, and are dissipated only by natural (windows and doors) or mechanical (fans, ventilating system) ventilation, or by particles plating out of the air onto surfaces, or by degradation of chemical vapors into other (potentially more or less toxic) substances. Poor outdoor air quality will not improve indoors unless steps are taken to remove the pollutants it contains. Such air can hardly be called "fresh" air at all.

... How much fresh air is enough?

The answer to this question depends on the nature of the building, the nature and number of the occupants, and the activities that take place within the building. The process of introducing and exhausting air into and out of buildings is known as air exchange, and it is usually expressed in terms of cubic feet of air introduced per minute per building occupant. In 1991 the Occupational Safety and Health Administration recommended that in non-industrial workplaces, 20 cubic feet of fresh air per minute per occupant should be the standard; they also recommended that in smoking lounges, 60 cubic feet of fresh air per minute per occupant should be the standard, with the proviso that the lounge air itself be vented directly outdoors and away from the building air intakes.

This amount of air is far more than can be obtained by passive ventilation through doors and windows, and is also impossible to achieve in a uniform manner throughout a building without the assistance of a ventilation system. It may also be inadequate to disperse air contaminants generated by activities within the building, such as cleaning and maintenance, and office activities such as operation of copying machines and some printers. It is certainly inadequate to disperse contaminants associated with some pest control methods and with building renovation. The OSHA recommended standard is thus probably best regarded as a minimum standard, not an optimum standard.

In most buildings, the ventilation system consists of heating and cooling appliances, fans, and ductwork. The air that is delivered though such a system is "conditioned" by heating or cooling appliances to provide thermal comfort as well as air. Because thermal conditioning and air exchange are integrated into the same system in this type of ventilation, factors that affect thermal conditioning can have a direct impact on the ventilation rate within the building. Notoriously in the 1970s and 1980s, the desire to minimize energy costs for heating and cooling gave rise to the "tightening" of buildings, so that heated and cooled air would remain heated and cooled for longer periods, and thus reduce energy consumption within the building. Since only thermal conditioning and its costs were considered, the need to replace the air within the building was overlooked. This set the stage for what has come to be known as "sick building syndrome."

Is it possible to achieve adequate air exchange as well as energy efficiency? Recently there has been considerable interest in energy recovery ventilation devices. These devices may be integral in new systems, or can be added onto existing ventilation systems. They are intended to capture heating and cooling energy contained in conditioned building exhaust air before it is discharged from the building. Some of these devices are designed to transfer the energy captured from the outgoing air to the stream of incoming air, so that it arrives at the heating or cooling appliance already partially heated or cooled. Others may discharge partially conditioned air directly into the return air stream within the building. Still others may simply discharge partially conditioned air into occupant spaces.

... Chemical and biological contaminants

In the NRC recommendation quoted at the outset of this article, emphasis was place on chemical contaminants within buildings that can contribute to ill health. These can find their way into indoor air from a variety of sources. These include building materials (resin-based wood products), furnishings, cleaning supplies (cleaners, disinfectants, waxes, polishes etc.), building maintenance activities (pest control), air "fresheners," personal maintenance products (fragrances and hairspray, for instance), emissions from appliances (from combustion appliances like unvented stoves to photocopying machines and printers), and renovation and redecoration supplies and processes (paints, varnishes, glues, adhesives, new carpet and upholstered furniture etc.). These contaminant sources can be broken down into two types: those that emit contaminants strongly when new but that decline in emissions over time, and those that are ongoing sources of continuous emissions.

In general, more durable materials introduced into a building are apt to be strong emitters initially, but emissions can be expected to decline over time. These materials include carpet, surface coatings like wall paints and varnishes, new upholstered furniture, and new building materials. Building occupants can be protected from these contamination sources by limiting their contact with new, acutely high-emission materials: Least toxic materials can be chosen from the outset. They can be installed only after airing out away from the building. The building can be ventilated at higher rates during installation and the initial period after installation.

Renovation and redecoration create serious acute emission problems. Removing old materials and installing new ones can release much dust and debris into the air, as well as fumes, fibers and vapors. Building occupants should be protected from exposure to all such emissions. Building areas undergoing renovations should be closed off from the rest of the building, and from the building's ventilation system. Elevators used by building occupants and visitors should not be permitted to open in areas undergoing redecoration or renovation.

As much of the work as possible should be done while the building is unoccupied. Newly renovated and redecorated premises should not be re-occupied until the area has been thoroughly aired out, and such spaces should receive additional ventilation for an extended period. For all these reasons, it is best to undertake renovation and redecoration during seasons when inevitable energy losses due to high ventilation rates can be minimized.

Protecting building occupants from emissions associated with cleaning, pest control, fragrance use and other "occasional" sources of contaminants is more problematical. Although "occasional," these activities occur so frequently that they may be regarding as ongoing and continuous. No sooner do the emissions from the last round of activity clear from a building than the next round is under way. Nevertheless, these contaminants can be controlled by implementing policies aimed at protecting IAQ. here are a few:

• Limit the use of high emission, odorous or scented products in the building wherever possible.
• Specify that the least toxic, least odorous materials be used. Do not rely on scented products to mask the objectionable odors of emissions within the building. A problem that requires scented masking is a problem that needs to be addressed at its source and corrected.
• Air freshening chemicals should never be introduced into ventilation systems or appliances.
• Pest control chemical use in particular should be limited to the least toxic effective product, used in the least amount, and only when there is a pest problem present. Building occupants and maintenance staff should not be permitted to use pest control products "ad lib;" such products are poisonous by nature, and require safe and responsible handling when used at all.

(Building managers and occupants should initiate and maintain pest control programs that minimize the building's attractiveness to pests (sanitation measures and habitat destruction are very helpful). Mechanical and other physical means can reduce or eliminate the infiltration of pests into the indoor space (window screens, caulking cracks and crevices). Such programs greatly reduce the occasions when pest control chemicals may be needed indoors. They area also cost-effective. Contact HEAL for more information about least toxic pest control.)

• Equipment that emits fumes during use can be confined to rooms with active ventilation and independent exhaust, to prevent the inevitable emissions from contaminating common air spaces.
• Unvented combustion appliances can be replaced with vented ones; large combustion appliances can be housed outdoors in dedicated building additions.
• Smoking should not be permitted in shared air spaces. It is preferable to have no smoking at all indoors (or out, for that matter). Outdoor smoking areas should be located away from building air intakes and passive ventilation sources (windows, doors, elevators).

Common indoor biological contaminants include pollens, housedust, dust mites and their debris, other insects and arthropods and their debris, molds and mildews. All of these can have health effects.

• Pollens from outdoors can worsen allergy and asthma; they can be controlled with air filtration devices designed to capture largish particles. Pollens indoors tend to be a seasonal problem, although in mild regions plants may pollinate nearly year-round.
• Housedust is not the same thing as "outdoor" dust. Housedust is a protein-containing product of the breakdown of many materials frequently found indoors (wood, paper, textiles, foods, plants, animal hair and dander, feathers, human and animal skin particles). Outdoor dust can be made of soils, minerals, plant materials or other more or less fine particulate matter. Housedust is allergenic; outdoor dusts may not be allergenic, but they may contain harmful particulate matter. Both need to be controlled by surface cleaning, and possible filtration.
• Insect and insect debris are very potent allergens. Microscopic dust mites are ubiquitous, reproduce readily, produce debris, and are impossible to "exterminate." However, frequent vacuuming (with a receptacle capable of capturing fine particles rather than releasing them through the vacuum cleaner's exhaust) provides effective control, especially when coupled with high efficiency particulate air filtration. The same method is also effective against other insect and arthropod debris; cockroach excreta and body parts are very common in building dusts, and are very potent allergens.
• Molds and mildews are responsible for a variety of problems indoors: from musty odors to actual destruction of property and health. Molds, like dust and dustmites, are ubiquitous in the environment. They require moisture to thrive, however, and indoor environments often provide exactly the right conditions to foster mold growth. Sometimes humidifiers pour too much moisture into the air. But frequently, moisture indoors arises from activities like bathing, showering, dishwashing and cooking, and laundering clothes. If moisture is not actively vented outdoors through exhaust fans, it will spread throughout the building until it condenses onto surfaces that are cooler than the water vapor is. Once this occurs, minute amounts of standing water can harbor and support mold growth.

Many people are aware that the contents of flooded buildings become moldy and must be discarded. The same is true of buildings that have been water-damaged due to fire control. Fewer are aware that such buildings may harbor greatly increased mold populations, and that these can quickly multiply to hazardous levels after the home has been cleaned and rehabilitated. Still fewer people are aware that molds can thrive in water indoors from any source including dripping pipes, overflowing tubs and toilets, broken water hoses on appliances and so on. Any wet condition indoors, no matter how it arose, is capable of supporting problematic levels of molds.

Molds attack textiles and paper, as well as building materials like plaster and wallboard, and wood. Some molds are allergenic to people, and cause allergies and asthma to worsen. Others are pathogenic-- they cause disease in people. Some of these diseases are mild and easily-diagnosed and treated, such as mold-related skin problems. Others are more severe, like the lethal hemorrhagic lung disease cause by stachybotrys species found in water-damaged homes. Still others can be caused by mold-contaminated foods.

Many people mistakenly think that mold problems are basically nuisance odor problems that are best addressed with air "fresheners." These products do nothing to control mold, but instead may either mask the mold odor, or numb the sensory apparatus in people so that they can't smell the mold odor, although it's still there. Other people mistakenly think that using "disinfectant" products will adequately and lastingly cleanse indoor surfaces from molds. In fact, given the right conditions, molds can overwhelm the residual activity of most disinfectant solutions, and in some cases can survive direct applications of some so-called disinfectants.

Cleaning is just one step in effective mold control, which consists of several steps: identify the source of the moisture and fix it, assess and repair moisture-related damage, implement moisture control strategies, and clean up any recurrence of moisture indoors as soon as it occurs, to prevent mold from proliferating.

It is worth noting that dust mites proliferate best in high humidity environments. Strategies that prevent moist conditions indoors may also be helpful in suppressing dust mite populations.

Next time: IAQ and the law of unintended consequences.

Sources:

• Ashford, N.A. and Miller, C.S.Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• EPA et al., Indoor Air Pollution, an Introduction for Health Professionals. (See HEALinks to IAQ on the Web.)
• EPA, Tools for Schools. (See HEALinks to IAQ on the Web.)
• Human Ecology Action League, Inc. MCS and ADA: A Guide to Accommodation. Atlanta: HEAL. 1994.
• Kosta, L. Pesticides indoors (series). The Human Ecologist #60 Winter 1993, #61 Spring 1994, #62 Summer 1994.
• Kosta, L. Moisture indoors: an interview with Dennis Creech (Southface Institute). The Human Ecologist #70, Summer 1996.
• Kosta, L. Air fresheners and health: an Interview with Rosalind C. Anderson. The Human Ecologist #67 Fall, 1995.
• Kosta, L. Post-flood health risks. THE Supplement, June 1997.Click here.
• National Research Council, Biologic Markers in Immunotoxicology. Washington DC: National Academy Press. 1992.
• Sturgis, P. Dust mite remediation The Human Ecologist (in press).

At a Glance: IAQ on the Web

As part of their on-line information service, HEAL has set up a page of links to information sources about indoor air quality and health. Topics include federal and state government information sources, mold and lung disease, research institutions and professional associations, on-line publications, IAQ and children's health. IAQ at home, toxic substances, and air cleaning and filtration devices (including information about the on-going controversy regarding ozone generators. Click here for HEALinks to IAQ on the Web. 

Indoor Air Quality (IAQ) Part 2: Fixing indoor air problems: odors.

by Louise Kosta
Chief writer, The Human Ecologist

Complaints from building occupants about the quality of the air supply prompts home owners and building managers to intervene to correct the problem. Unfortunately, sometimes the problem is identified accurately but the solution implemented to resolve it is not appropriate. At other times, the problem is not identified accurately, and efforts that fix the identified problem do not result in improved air quality. In both cases, unintended consequences can result.

Odors in buildings: The wrong "fix"-- air fresheners

One of the most frequently encountered complaints about indoor air quality (IAQ) is expressed as concern about unpleasant odors. A commonly used "solution" for odor problems in buildings is the use of air freshening products and devices. The effort is to replace an unpleasant odor with one that is perceived as more pleasant. However, these products do nothing to eradicate the unpleasant odor. In addition, they can have negative consequences of their own. Moreover, reliance on air freshening products or devices can leave unresolved problems that require appropriate intervention in order to forestall serious consequences to building integrity and occupant health.

In 1995, respiratory toxicologist Rosalind Anderson told The Human Ecologist that air fresheners tested in her independent laboratory were incapable of removing offensive odors, but were capable of temporarily numbing the sense of smell in those exposed to them. Although this physical change may be reversible and innocuous, it points out how air fresheners can work: by blocking the sense of smell, air fresheners cause building occupants become unaware of offensive odors. The people change, but odors themselves are not affected.

In addition, the use of air fresheners may have unintended health impacts, because the effects of air freshener exposure on people may not be limited to sensory numbing. At the time she spoke to The Human Ecologist, Anderson had completed an investigation of the effects of air fresheners on test animals. The animals were exposed to vapors from the air fresheners, which they breathed. Their exposures were thus similar to those of people in the presence of air fresheners. In her investigation, Anderson found that, even at the lowest level of air freshener exposure she tested, the animals developed symptoms of sensory and pulmonary irritation. The higher the exposure, the more severe the effects, until the test animals developed the equivalent of asthma in people. At the medium and high levels used in her test, the animals also developed nervous system symptoms, and at the very highest levels, the animals had all of the symptoms named, plus tiny hemorrhages in their ears. At this level of testing, some of the animals died.

Anderson concluded: "People should try to evaluate their real need for air fresheners. Are they trying to solve an odor-related problem? Air fresheners are not a good solution -- they may not even be a healthy solution. . . . Introducing air fresheners into a problem environment is apt to compound building air-quality problems, not solve them."

Odors in buildings: The right "fix"

How should problem odors in buildings be addressed? First try to identify the cause, and if possible, eliminate it?

Some problem odors are related in contaminants in the outdoor air that is brought indoors. These can include air pollutants such as automotive exhaust, as well as odors from garbage cans and dumpsters. In the case of the former, drawing outdoor air from a source oriented away from the pollution source can help mitigate the problem, although addition air treatment within the building may be needed to absorb offensive odors and vapors. In some cases, automotive exhaust from idling vehicles can be controlled by prohibiting idling near areas of building active (ventilating system) and passive (windows and doors) air intake. (Similarly, fueling of outdoor equipment such as lawnmowers should be done away from building air intakes.) In the case of garbage disposal areas, they should be cleaned and the containers tightly covered and frequently emptied.

In addition to these obvious sources of offensive odors, there are other, less visible causes of offensive odors. One is biological contaminants near the ventilation system air intakes. Common biological contaminants included leaf and grass litter, dead animals and animal droppings. Since building air intakes may be located on parts of the building not usually seen by building occupants (e.g. roofs), biological contaminants can accumulate unbeknownst to building occupants. The remedy in this case is to visit the air intake areas and clean them up. Animals can sometimes get into a building's ventilation system, where their waste and litter can accumulate in ductwork; animals occasionally die in ductwork, as well. Air moving through the ducts spread odors from these contaminants throughout the building. In this case, professional ventilation service personnel may need to be called in to clean up the problem, and to block animal access to the ventilation system so that the situation does not arise in the future.

Cooking, cleaning, hobby and personal maintenance activities can all add transient unpleasant odors to the indoor environment. Cooking releases smoke and vaporized fats, as well as odors intrinsic to foods as they cook. Cleaning may stir up dusts and molds, and commonly involves the introduction of solvents and fragrances into the air. Hobbies such as painting, and wood- and metal-working, as well as sports equipment maintenance requiring solvents and oils, can introduce many chemicals into the indoor environment. Gardening indoors can release pesticides and molds into indoor air, as well as vapors emitted from the growing plants themselves. Odors from personal maintenance range from the use of scented grooming products to occasional use of products with harsh or irritating fumes (such as hair colorings or permanent solutions). Smoking indoors is a serious source of indoor air pollutants, as well as unpleasant odors. In all of these situations, identification of the activity giving rise to the offensive odor should be done first. Is the activity constant (ongoing or multiple times per day) or intermittent? If it's constant, it may be necessary to add active ventilation to the areas where the activity takes place.

Kitchen and bath exhaust fans can solve many of these problems, as long as the exhaust is vented outdoors and away from the building air intake areas. If the problem is intermittent, it may be possible to avoid the build up of offensive odors by either moving the activity to a well-ventilated area of the building, or removing it from the building altogether. Building-wide activities like cleaning and waxing may involve many substances that are potentially harmful to building occupants. They should be undertaken with increased active and passive ventilation (open windows and ventilation system fans), and with as few building occupants present as possible.

Permitting smoking indoors is simply unwise from the health and sanitation point of view. In many public buildings, commercial establishments and workplaces it is forbidden altogether. However, in households with smokers, it may be possible to limit the amount of smoking-related pollution that occurs by confining smoking to areas of the home with powerful exhaust fans vented to the outdoors and away from air intakes. The use of particulate and gas air filtration devices may also bring some relief from smoking related pollution. Aerosol sprays are not a good solution to indoor tobacco smoke odors, as they add to the chemical contents of the air without diminishing the risks posed by the tobacco smoke itself.

Cleaning may involve the use of solvents, cleaners, chlorine-containing compounds, and ammonia-containing compounds. Many contain added scent materials, and many are intrinsically odorous themselves. It is possible for individual products of all of these types to have health effects. Selection of least-toxic products that are capable of accomplishing the cleaning task is highly recommended. (Read product labels: the products recommending the fewest precautions during use-- such as eye and skin protection, added ventilation, and proper disposal recommendations-- are those least likely to cause indoor air problems. The exception to this rule concerns highly scented but otherwise innocuous products: In these products, the added scent may itself create problems.)

Cleaning tasks may also be simplified by choosing building and decorating materials that do not require the use of high emission maintenance products. Examples are smooth tile and hardwood floors (clear water, soap and water, and dustmop maintenance) with area rugs (home or commercial laundry cleaning ), rather than carpet (vacuuming, spot cleaning, occasional full cleaning with solvents, other odorous materials, stain repellents and other chemicals). Don't use carpet deodorizers, particularly scented ones; some perform functions similar to air fresheners, and some are sources of particulate pollution with potentially irritating substances. An odorous carpet needs to be cleaned and thoroughly dried, not perfumed.

Cleaning may also stir up dusts and molds from the surfaces cleaned. Use of damp wipes for dusting, vacuum cleaners capable of capturing and holding fine particles, and the use of air filtration devices after cleaning is completed can greatly minimize redistribution of dusts and molds through the indoor environment. Note: When undertaking cleaning of very soiled or moldy indoor areas, do not run the ventilation system until the visible soil or mold has been cleaned and removed. Running the ventilation system during such clean-up efforts may simply move soils and molds throughout the building, and create conditions within the ventilation system's ductwork for severe contamination.

Renovation, remodeling and redecorating can produce many unpleasant odors in buildings. These odors should not be regarded as nuisance odors, but as evidence of indoor air pollution with chemical emissions. Some of these odors are unavoidable, as when new surface coatings are applied to walls, ceilings and floors. The odors such coatings produce typically subside rapidly as the finished surface dries and cures. Until drying and curing is complete, ventilation rates within the building should be increased. This is best accomplished by by-passing the ventilation system itself, and using auxiliary fans to vent air into and out of the building. Such a by-pass will prevent chemicals from contaminating the interior structures in the ventilation system, which will prolong the period during which fumes are distributed within the building.

Installation of new flooring materials (wall-to-wall carpet, vinyl tile or sheet flooring) is also a major source of fumes and vapors. Such installations should be conducted as described above, for surface coatings. In addition, new carpet should be thoroughly aired away from the building before it is installed, and thoroughly vacuumed once installed. In some cases, it may be desirable to have the new carpet steam cleaned before (most desirable) or just after it is installed. Vinyl flooring should be thoroughly washed with an unscented cleaner as soon as it is installed, and frequently thereafter. Both carpet and vinyl flooring emit large quantities of vapors when newly installed. The speed with which these emissions decline depends on the actual composition of the materials. Air filtration devices that capture both gases and particles may offer helpful mitigation after the intense emissions from new installations dissipate. However, reliance on such devices may not offer adequate protection to the health of susceptible individuals.

Building occupants frequently become accustomed to building odors, and do not perceive them during periods of sustained occupancy. However, on returning to a closed building after hours or days away, building odors may again be perceptible . If so, the odors should be addressed in the manner described above, not masked with air freshening products or devices.

Summing up: odors in buildings

Unpleasant odors are not nuisances. In some cases they point to serious problems that need to be resolved. Instead of reaching for the air freshener or deodorizing spray, consider the following:

• Linger cooking odors may indicate poorly ventilated cooking areas. Install an exhaust fan.
• Musty smells indicate a past or current moisture problem. Find the moisture and clean it up. Clean or discard mold-damaged items. Find the source of the moisture and fix it. Use dehumidification equipment if necessary.
• Increased foul odors associated with the building heating or cooling "on" cycle indicate contamination in the ventilation system or in the building air intakes. Call a ventilation specialist. Clean up problems and take steps to prevent their recurrence.
• Remodeling and redecoration odors are not nuisances, but pollutants-- some of them potential health threats. Use greatly increased ventilation during and just after these processes, preferably by-passing the building ventilation system.
• Activities that generate strong odors should either be relocated away from the building, or limited to areas of the building with their own dedicated exhaust systems vented to the outdoors and away from air intakes.
• Cleaning products should be selected for low emissions and low toxicity, as well as cleaning efficiency. A strong odor does not indicate an efficient cleaning product.
• Building redecorating and remodeling materials, and new furnishings, should be selected for low emission, durability, and ease of maintenance with low-toxicity products.

Respiratory toxicologist Rosalind Anderson told The Human Ecologist, "Our building investigations have indicated that problems with IAQ are usually related to a number of different factors. Fixing one or two of them will not fix the problem in the building, but fixing all of them will. Ventilation alone is not the answer; neither is sanitation. Ventilation, sanitation, emission source reduction and other factors are all part of the picture."
Sources:

• Ashford, N.A. and Miller, C.S.Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• EPA et al., Indoor Air Pollution, an Introduction for Health Professionals. (See HEALinks to IAQ on the Web.)
• EPA, Tools for Schools. (See HEALinks to IAQ on the Web.)
• Hays, .S.M. et al., Indoor Air Quality: Solutions and Strategies.NY et al: McGraw-Hill, Inc. 1995.
• Human Ecology Action League, Inc. MCS and ADA: A Guide to Accommodation. Atlanta: HEAL. 1994.
• Kosta, L. Pesticides indoors (series). The Human Ecologist #60 Winter 1993, #61 Spring 1994, #62 Summer 1994.
• Kosta, L. Moisture indoors: an interview with Dennis Creech (Southface Institute). The Human Ecologist #70, Summer 1996.
• Kosta, L. Air fresheners and health: an Interview with Rosalind C. Anderson. The Human Ecologist #67 Fall, 1995.
• Kosta, L. Post-flood health risks. June 1997
• Muilenberg, M and Burge, H. Aerobiology. Boca Raton FL: Lewis Publishers.1996.
• Sturgis, P. Dust mite remediation The Human Ecologist (in press).

At a Glance: IAQ on the Web

As part of their on-line information service, HEAL has set up a page of links to information sources about indoor air quality and health. Topics include federal and state government information sources, mold and lung disease, research institutions and professional associations, on-line publications, IAQ and children's health. IAQ at home, toxic substances, and air cleaning and filtration devices (including information about the on-going controversy regarding ozone generators. Click here for HEALinks to IAQ on the Web.

Indoor Air Quality (IAQ) Part 3:
Protecting special people with special problems.

by Louise Kosta
Chief writer, The Human Ecologist

Introduction

There are estimates that in industrialized countries, most people spend 90% of their time indoors, regardless of their health status. Home, school, work, and travel to and from these and other activities, consume many waking hours-- and sleep, of course, takes place indoors, too. For people indoors, indoor air is the air they breathe most of the time. IAQ is therefore important to everyone.

Many different people have indoor air quality (IAQ) responsibilities. They are building managers and owners, employers and industrial facility managers, school and healthcare facility administrators -- and home owners (and renters). All of these people engage in or supervise activities that affect IAQ: from major maintenance and renovation projects, to daily activities like cooking, cleaning, and hobbies.

Many considerations may come into play in making decisions about what kinds of substances to introduce into an indoor environment, and when to introduce them. These can include comparative costs, ease of application, performance standards, and materials management.

One consideration that can be overlooked is protecting the health of building occupants. Too often, health problems arising toxic exposure indoors are not anticipated and avoided. Very often, the connection between health problems that do arise and indoor exposures are not recognized as such. In many cases, health problems are addressed entirely independently of environmental exposures, often to the detriment of the patient, and very often in such a way that harmful exposures continue unchecked.

'One size fits all' approaches to indoor materials selection and application may not protect the most vulnerable occupants of indoor spaces. This article discusses some well-identified vulnerable groups, and the effect that common indoor pollutants may have on them. Pollutants and their effects are taken from EPA's Indoor Air Pollution: An Introduction for Health Professionals. Information on vulnerable subpopulations is taken from the sources indicated.

What makes a person susceptible to indoor air pollution?

It is a commonplace of toxicology that 'the dose makes the poison.' That is, it takes a certain amount of a substance to provoke a toxic effect, and any exposure below that amount can reasonably be expected to be harmless. Unfortunately, it's not that simple.

It's equally well known, but not so catchily phrased, that other factors play a key role in producing toxic effects. These include the age, sex, and nutritional status of individuals, their genetic make-up, and their health status. In general, the very young, the elderly, the malnourished and the ill are more susceptible to adverse effects from toxic exposures. Specific genetic susceptibilities can also increase the risk of toxic effects in affected individuals.

Note that 'the dose makes the poison' is about the substance, but that the other modifiers 'are about' individual people. Some of these people-factors are well understood, at least in part.

Who is susceptible-- and why?

The individual susceptibility of any single person is difficult to determine with certainty. However, the following groups have been identified as susceptible to adverse effects from various kinds of environmental exposure. Source for information on each of these groups is included in each entry.

Pregnant women are extra susceptible because of the overall taxing physical stresses of pregnancy, as well as organ and metabolic changes associated with pregnancy.

See:

• J. D. Beasley , Chapter 3. Nutrition and disease. Chapter 8. The next generation. The Betrayal of Health. NY: Random House/Times Books, 1993.
• J.D.Brain et al. (eds.) Variations in Susceptiblity to Inhaled Pollutants. Baltimore: Johns Hopkins University Press 1988.
• Arthur C. Upton and Eden Graber, Chapter 5: The brain and the nervous system. Chapter 11. Reproductive effects and prenatal exposures. Chapter 32: Of special concern: infants and children. Staying Healthy in a Risky Environment. NY et al.: Simon & Schuster. 1993.
• J. Herzstein, Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994.

Unborn and very young children are extra susceptible to toxic effects because their bodies are not completely developed. The rapid cell division characteristic of development and growth makes their genetic material especially vulnerable to toxic insult. Young children breathe more air, drink more water, and eat more of certain foods than adults do (per unit body weight), and thus potentially receive larger doses of toxic substances per unit body weight than do adults in the same environment. Their small body size alone means that less of a toxic substance is needed to provoke a toxic effect.

See:

• J. D. Beasley , Chapter 3. Nutrition and disease. The Betrayal of Health. NY: Random House/Times Books, 1993.
• Arthur C. Upton and Eden Graber, Chapter 5: The brain and the nervous system. Chapter 32: Of special concern: infants and children. Staying Healthy in a Risky Environment. NY et al.: Simon & Schuster. 1993.
• J. Herzstein, Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994.

The elderly are more susceptible to toxic effects not only because of the potential for existing disease, but also because protective factors (such as efficiency in metabolizing and excreting foreign substances) are in decline. Adequate nutrition may decline with age as well, particularly if the person is acutely ill or taking drugs for one or more chronic conditions. Declines in appetite, as well as in the abilities to taste and smell, can also impair nutrition. Increasing frailty, particularly in the absence of household help, may limit food choices or preparation methods. Similarly, impaired vision may have an adverse impact on food selection, preparation and consumption. And finally, impoverishment may contribute to susceptibility in the elderly: the actual or perceived inability to obtain appropriate food, household help, health-related care, and other services can undermine overall health in the elderly.

See:

• T. D. Griffiths and P.J. Meechan, Biology of aging. In Ferraro, K.F. Gerontology: Perspectives and Issues. New York: Springer, 1990.
• W.S.Cain and J. Stevens, Uniformity of olfactory loss in aging. In C.Murphy et al. (eds), Nutrition and the Chemical Senses in Aging: Recent Advances and Current Research Needs. Annals of the New York Academy of Sciences Volume 561, 1989. NY: New York Academy of Sciences .
• Cheng, Y. et al., Relation of nutrition to bonelead and blood lead in middle-aged to elderly men. American Journal of Epidemiology. 147:1162-1174, 1998.
• A.M. Ferris et al., Effect of olfactory deficits on nutritional status. In C.Murphy et al. (eds), Nutrition and the Chemical Senses in Aging: Recent Advances and Current Research Needs. Annals of the New York Academy of Sciences Volume 561, 1989. NY: New York Academy of Sciences .
• J. Herzstein, Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994.
• H. J. Hoffman et al., Age-related changes in the prevalence of smell/taste problems among United States adult population. In C. Murphy (ed.), Olfaction and Taste XII: An International Symposium. Annals of the New York Academy of Sciences Vol. 855 NY: New York academy of Sciences 1998.
• Arthur C. Upton and Eden Graber, Chapter 5: The brain and the nervous system. Staying Healthy in a Risky Environment. NY et al.: Simon & Schuster. 1993.
• J. Zeller. Drug induced deficiencies are widespread and treatable. American Druggist 8:53, 1998.

The malnourished (including people with eating disorders, acute or chronic illness, certain metabolic disorders, and people with subclinical and clinical nutritional deficiencies) are at risk because their diets do not provide sufficient quantities of nutrients needed to support metabolism and excretion of toxic substances.

Acute or chronic illness can have a severe temporary (acute) or permanent(chronic) effect on nutritional status. Acute illnesses that involve vomiting and diarrhea can deplete the body of critical nutrients as well as interfere with adequate food intake. Chronic illnesses that involve long-term drug therapy may set the stage for drug-induced dietary deficiency. Metabolic disorders may impair the body's absorption and utilization of nutrients, even when the diet is adequate. All of these conditions modify the affected individual's ability to handle toxic exposures.

[Note: Poverty is not synonymous with malnutrition, nor is malnutrition synonymous with poverty-- wealthy but uninformed people can consume inadequate nutrients through poor choices, weight-loss diets that are inadequate or poorly planned, and eating disorders, which can affect persons of any economic status. But poverty is a risk factor for malnourishment-- insufficient money to purchase nutritious foods can limit access to a good diet, even when the consumer is well-informed about what constitutes a nutritious diet.]

See:

• J. D. Beasley , Chapter 3. Nutrition and disease. Chapter 8. The next generation. The Betrayal of Health. NY: Random House/Times Books, 1993.
• J. Krohn, Detoxification pathways. The Human Ecologist #80, Winter 1998. cf. S. E. Manahan, Toxicological Chemistry. Chelsea MI: Lewis Publishers 1992.

The chronically ill are at increased risk for harm from toxic exposure for several reasons.
Malnourishment is a risk, because illness may impede adequate food intake or nutritious diet. The drugs taken for chronic illnesses may impede the ability to metabolize the food they do ingest. Drugs may also alter the function of digestive organs, and interfere with absorption. The illness itself may affect organ functions that are essential to metabolism of toxics. Organ functions essential to life may also be affected by chronic illnesses. (Illnesses with these effects need not necessarily be perceived as dire: They include asthma and allergy, both of which have chronic effects on the respiratory system.)

The illness may also interfere with other aspects of healthy living (exercise, adequate hydration), and may involve alterations in behavior because of changed brain chemistry. Illnesses that involve immune suppression, either illness-induced (as in HIV/AIDS), drug- induced (as in organ transplant patients), or treatment-induced (as in radiation and cancer chemotherapy) can alter the body's ability to withstand toxic exposure. Treatment regimens that involve multiple drugs that tax the same metabolic pathways as toxic substance metabolism can also increase vulnerability to toxic exposure.

See:

• J.D.Brain, et al. (eds.) Variations in Susceptiblity to Inhaled Pollutants. Baltimore: Johns Hopkins University Press 1988.
• J. Herzstein, Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994.
• J. Zeller. Drug induced deficiencies are widespread and treatable. American Druggist 8:53, 1998.
• Curtis, L. Fungi and their health effects. The Human Ecologist #73, Spring 1997.

Genetic make-up can affect vulnerability to toxic exposure. The Environmental Human Genome Project , a project of the National Institute of Environmental Health Sciences, will tell us a lot about this in the future. At the moment, we know that there are heritable differences in how groups of people metabolize certain chemicals and drugs. We also know that certain groups seem to be more susceptible to certain cancers than are other groups, which may signal, at least in part, an inborn susceptibility to certain toxic exposures. There is good evidence that some diseases 'run' in families. But little is known at the moment about individual genetic vulnerability to toxic exposure. Although information about genetic variants and their effects is growing exponentially, meaningful testing for patients is almost entirely lacking. At the moment we know that there are differences, and that the differences may be important, but we have no easy way of telling who has these differences, or what to do about them.

See:

• J. Herzstein, Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994.
• J.Albers, Understanding gene-environment interactions. Environmental Health Perspectives 105(6): . 578-580. June 1997.
• Weinhold, R. Beginning research on genetic vulnerability to environmental toxins. The Human Ecologist 78, Summer 1998.

Understanding susceptibility

Some facts about individuals are quite apparent, even from the information above. Over his or her lifetime, each of us will experience periods of increased vulnerability to toxic exposure. Sometimes these periods will be comparatively brief, as during particular stages of development during prenatal and neonatal life. Early childhood lasts only a few years. Pregnancy lasts 9 months. Even a bout of cancer may last less than a year. Other conditions, acquired at any stage of life, may last for years without seriously impairing subjective well-being, although they may increase vulnerability to toxic exposures. Still other chronic conditions both undermine well-being and increase vulnerabilty. The point is, no one has a lifetime guarantee against harm from toxic exposure. We arrive with inborn susceptibilities of which no one is aware, and as we progress through life, we undergo periods when the 'dose' it takes to induce a toxic effect in us is reduced because of circumstances other than the innate toxicity of the substances to which we're exposed.

To which pollutants are these groups susceptible?

EPA has identified 6 indoor air pollutants that have the potential to affect human health. The following discussion concerns five of them (the sixth issue identified by EPA, sick building syndrome, will be discussed in a future article on building related illnesses). The five pollutants are:

• environmental tobacco smoke
• other combustion products
• biological pollutants
• volatile organic compounds
• heavy metals

Susceptible groups are likely to be especially sensitive to these pollutants, as indicated in the following discussion.

Environmental tobacco smoke: Rhinitis, nasal congestion, pharyngitis, cough, wheezing, worsening asthma, difficulty breathing, eye irritation, headache, dizziness.

Pregnant women: breathing for two. Intake of airborne pollutants may affect both mother and fetus. Intake of carbon monoxide interferes with oxygen absorption, which is undesirable for both mother and fetus. The irritant gases and particles in tobacco smoke may also interfere with maternal respiration and decrease oxygen available to the fetus. The carcinogens in sidestream tobacco smoke may be particularly hazardous to fetuses undergoing rapid cell division and growth.

Infants and small children: See general discussion of infants and small children, above. In addition, irritant gases and particles may contribute to respiratory distress, especially in allergic and asthmatic children. Asthma is a leading cause of school absenteeism in the US. Tobacco smoke exposure may contribute to middle ear infections. Tobacco smoke has been associated with sudden infant death syndrome, although it is unclear if the association is between exposures in utero from maternal smoking during pregnancy, or from exposures after birth. Chronic exposure to tobacco smoke in early life may lead to reductions in lung growth and lung function. Both can have lifelong ill effects.

The elderly: Airborne pollutants of all kinds place an extra burden on organs that may already be diseased or injured. With age, the respiratory tract may become less efficient, as hardened blood vessels are less capable of carrying out oxygen exchange, life-long injury due to past exposures manifests itself in less elastic tissues in the respiratory tract, and other conditions that affect the cardiovascular and respiratory systems come to the fore (heart disease, chronic bronchitis, emphysema). Tobacco smoke exposure may worsen hypertension, a major contributor to stroke and heart disease. Note that exposures that promote dizziness are a particular hazard to the elderly, who are at increased risk for injury due to falls.

The chronically ill: Symptoms induced by sidestream tobacco smoke exposure may already be present due to chronic illness, and are exacerbated by smoke exposure. Control of these symptoms may involve higher doses of therapeutic drugs, or more different kinds of drugs; either way, increased drug intake puts the chronically ill person, who may already be at risk for adverse reactions to drugs, at even higher risk. Such reactions are a significant factor in poor health in the chronically ill. Breathing irritant gases and particles in tobacco smoke can produce tissue inflammation in the bronchi, lungs and sinuses. This provides favorable conditions for infectious agents. Respiratory infections place additional burdens on the cardiovascular system, can interfere with adequate nutrition, and may require therapeutic drug treatment. Illnesses that affect mobility also may involve deficits in respiratory efficiency; smoke exposure can worsen this deficit. People taking drugs that suppress immunity are at increased risk for respiratory infection.

Diabetics, people with kidney disease, and those with hypertension may be particularly susceptible to the effects of tobacco smoke on blood pressure.

Two very large groups, the allergic and the asthmatic, are especially susceptible to acute effects from tobacco smoke exposure. Both conditions involve inflamed respiratory tract tissues. This underlying inflammation makes the tissue especially sensitive to irritant gases and particles present in polluted air, including those in tobacco smoke. In addition to increasing the risk of respiratory tract infection, pollutants like tobacco smoke seem to potentiate the effects of both allergens in allergic people, and the triggers that set off asthma attacks.

The following chronic conditions are all made worse by low level chemical exposures including those contained in tobacco smoke:

• multiple chemical sensitivity (see Ashford, N.A. and Miller, C.S. Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• reactive airway dysfunction syndrome (see Chest 88(3)376-384, 1985)
• reactive upper airway dysfunction syndrome (see Archives of Environmental Health 48(1)14-18, 1993)
• irritant associated vocal cord dysfunction (see Journal of Environmental and Occupational Medicine

• 40(2):136-142, 1997)

• chemical headache exposure syndrome (see Headache 22:555-559, 1993)
• reactive intestinal dysfunction syndrome (see Archives of Environmental Health 53(5):354-358, 1998)

Genetic susceptibility: Not known. However, it is known that not everyone who smokes tobacco gets tobacco-related disease. What makes smokers who get sick different from smokers who do not is not known. It is also not known how these differences (if any) are distributed among non-smokers who are exposed to sidestream tobacco smoke. Researchers have found genetic differences among individuals in their production and use of enzymes important to metabolizing foreign chemicals. Some of these differences appear to affect individual risk of developing certain cancers and certain nervous system diseases.

See:

• L.G. Costa and L, Manzo, Biomarkers in occupational neurotoxicology. In L. G. Costa and L. Manzo, Occupational Neurotoxicology. Boca Raton et al.: CRC Press 1998.

Other combustion products: nasal inflammation and congestion, pharyngitis, cough, wheezing, worsening asthma, eye irritation, headache, dizziness, lethargy, fatigue, malaise, cognitive impairment, personality change, rapid heartbeat, retinal hemorrhage. [Note: Combustion byproducts indoors include some of the same pollutants found in outdoor air pollution: carbon monoxide, nitrogen dioxide, and sulfur dioxide.]

Infants and small children: See general discussion of susceptibility of infants and small children, above. In addition, irritant gases and particles may contribute to respiratory distress, especially in allergic and asthmatic children. Asthma is a leading cause of school absenteeism in the US.

Pregnant women: See general discussion of susceptibility of pregnant women, and the discussion of tobacco smoke and pregnancy, both above.

The elderly: Airborne pollutants of all kinds place an extra burden on organs that may already be diseased or injured With age, the respiratory tract may become less efficient, as hardened blood vessels are less capable of carrying out oxygen exchange, life-long injury due to past exposures manifests itself in less elastic tissues in the respiratory tract, and other conditions that affect the cardiovascular and respiratory systems come to the fore (heart disease, emphysema). Note that exposures that promote dizziness are a particular hazard to the elderly, who are at increased risk for injury due to falls. Note as well that lethargy, fatigue, cognitive impairment, and personality change may be attributed to 'getting old,' and treated with drugs-- whereas the symptoms may arise from, or may be worsened by, environmental exposure to combustion products. Increased drug intake puts the elderly at increased risk for adverse drug reactions.

The chronically ill: Symptoms induced by combustion byproduct exposure may already be present due to chronic illness, and are exacerbated by these exposures. Control of these symptoms may involve higher doses of therapeutic drugs, or more different kinds of drugs; either way, increased drug intake puts the chronically ill person, who may already be at risk for adverse reactions to drugs, at even higher risk. Such reactions are a significant factor in poor health in the chronically ill. Breathing the irritant gases of combustion byproducts can produce tissue inflammation in the bronchi, lungs and sinuses. This provides favorable conditions for infectious agents. Respiratory infections place additional burdens on the cardiovascular system, can interfere with adequate nutrition, and may require therapeutic drug treatment. Illnesses that affect mobility also may involve deficits in respiratory efficiency; combustion byproduct exposure can worsen this deficit. People taking drugs that suppress immunity are at increased risk for respiratory infection.

Two very large groups, the allergic and the asthmatic, are especially susceptible to acute effects from combustion byproduct exposure. Both conditions involve inflamed respiratory tract tissues. This underlying inflammation makes the tissue especially sensitive to irritant gases and particles present in polluted air. . In addition to increasing the risk of respiratory tract infection, irritant gases in combustion byproducts, both indoors and out, seem to potentiate the effects of both allergens in allergic people, and the triggers that set off asthma attacks.

The following chronic conditions are all made worse by low level chemical exposures, including combustion byproducts :

• multiple chemical sensitivity (see Ashford, N.A. and Miller, C.S. Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• reactive airway dysfunction syndrome (see Chest 88(3)376-384, 1985)
• reactive upper airway dysfunction syndrome (see Archives of Environmental Health 48(1)14-18, 1993)
• irritant associated vocal cord dysfunction (see Journal of Environmental and Occupational Medicine 40(2):136-142, 1997)
• chemical headache exposure syndrome (see Headache 22:555-559, 1993)
• reactive intestinal dysfunction syndrome (see Archives of Environmental Health 53(5):354-358, 1998)

Genetic susceptibility: Not known. Researchers have found genetic differences among individuals in their production and use of enzymes important to metabolizing foreign chemicals. Some of these differences appear to affect individual risk of developing certain cancers and certain nervous system diseases.

See:

• L.G. Costa and L, Manzo, Biomarkers in occupational neurotoxicology. In L. G. Costa and L. Manzo, Occupational Neurotoxicology. Boca Raton et al.: CRC Press 1998

Biological pollutants [animal dander, molds, dust mites, infectious disease organisms]: nasal congestion and inflammation, pharyngitis, cough*, wheezing*, worsening asthma*, difficult breathing, severe lung disease**, eye irritation, headache, dizziness, lethargy, fatigue, malaise, nausea, vomiting, anorexia, rashes, fever, chills. [* not included in EPA's analysis; see comments on allergy and asthma under chronic illness; ** not included in EPA's analysis; see comments on infants and small children]

The unborn and very young : Mold species may be of particular concern, particularly Stachybotrys species. These molds have been associated with lung hemorrhages in infants and small children and with sudden infant deaths. Childhood asthma and allergies may be difficult to control in the presence of biological contaminants, and may lead to increased susceptibility to respiratory infections. Some toxins produced by molds may be especially hazardous to the unborn.

Pregnant women: Allergic or asthmatic pregnant women may experience worsening symptoms in the presence of biological contaminants.

The malnourished : Impaired resistance to infectious disease organisms, including those of Legionnaires' Disease, tuberculosis, others. This impaired resistance is further exacerbated with concurrent tobacco smoke exposures.

The elderly: Impaired resistance to infectious disease organisms, including those of Legionnaires' Disease, tuberculosis, others. Note that declining sense of smell may fail to detect mold contamination in the home, permitting ongoing exposures. Note too that symptoms of some illnesses caused by biological contamination may be mistaken for viral or bacterial disease, leading to inappropriate treatment and increased risk of adverse drug reactions. Non-specific flu-like symptoms may also lead to delays in proper diagnosis and ongoing exposures.

The chronically ill: Biological contaminants pose special risks to people with respiratory disease, particularly since contaminant-related illness may be interpreted as a worsening of the chronic condition, leading to inappropriate treatment, increased risk of adverse drug reactions, and ongoing exposures to contaminants. Note too that symptoms of some illnesses caused by biological contamination may be mistaken for viral or bacterial disease, leading to inappropriate treatment and increased risk of adverse drug reactions. Non-specific flu-like symptoms may also lead to delays in proper diagnosis and ongoing exposures. Asthma and allergies may be difficult to control in the presence of biological contaminants; poor control of the underlying disease may increase susceptibility to bacterial infection, leading to more drug therapy and increased risk of adverse drug reactions.

Genetic make-up: Unclear. Allergies and asthma 'run' in families, but susceptibility to particular allergens and irritants may be individual as well as genetically determined.

Volatile organic compounds [formaldehyde, pesticides, solvents, cleaning agents]: nasal congestion and inflammation, nosebleed, wheezing, worsening asthma, difficult breathing*, eye irritation, headache, dizziness, lethargy, fatigue, malaise, nausea, vomiting, anorexia, cognitive impairment, personality change, rashes, retinal hemorrhage, muscle aches. [*Not mentioned by EPA. See information under chronic illness.]

The unborn and very young : Toxic chemicals in solvents and in carbamate and organophosphate pesticides pose risks to the developing nervous system. Nervous system damage sustained early in life may not manifest itself until much later. Pyrethroid pesticides may aggravate allergy and asthma.

Formaldehyde is a probable human carcinogen, and may pose a risk to developing fetuses and children.

It is also an irritant, and may adversely affect allergic and asthmatic children. Irritants in cleaning products may cause respiratory inflammation and increased susceptibility to bacterial infection. Loss of appetite may interfere with adequate nutrition and increase susceptibility to both infection and to adverse effects of toxic exposure.

Pregnant women : Increased respiratory distress in pregnant women with allergies and asthma. Symptoms of toxic effects from VOCs may be mistaken for 'morning sickness' and lead to ongoing exposure. Loss of appetite may lead to nutritional deficiencies harmful to both mother and fetus (mother may have increased susceptibility to toxic exposure; fetus may suffer nervous system damage due to lack of maternal nutrient intake).

The malnourished : Inadequate diet may increase toxic effects of exposures due to lack of nutritional support of body detoxification systems. Flu-like symptoms associated with exposure may be misinterpreted and lead to further exposure.

The elderly: Fatigue, cognitive impairment and dizziness may be attributed to age or to medications, thus allowing exposure to continue. Symptoms may lead to increased medications and increased risk of adverse drug reactions. Loss of appetite may lead to inadequate diet and increased susceptibility to toxic exposure. Deficits in sense of smell may lead to ongoing exposures due to failure to detect their odors. Difficult breathing may affect mood. People with neurological conditions involving cholinesterase production and metabolism may suffer increased symptoms due to pesticide exposure. Large exposures to pesticides may induce neurological disease in people with age-related neurological decline.

The chronically ill: See above entry, the elderly. In addition, people with allergies and asthma may experience greatly increased symptom frequency and severity, especially in the presence of irritants (formaldehyde, fragrances, solvents, cleaning agents) and allergens (pyrethroid pesticides, fragrances). People with chronic obstructive pulmonary disease may experience symptoms similar to allergic and asthmatic. People with heart disease and asthma may experience increased cardiac and asthmatic symptoms. People with chemical sensitivity may experience greatly increased symptom severity and frequency. Note that cognitive impairment, fatigue, malaise, nausea, headache and other non-specific symptoms are frequently attributed to 'psychological' problems in the young, and to 'aging' in the elderly. Both attributions may be in error, and such errors can lead to continuing exposure, excessive medication, adverse drug reactions, or combinations of all three.

The following chronic conditions are all made worse by low level chemical exposures including VOCs:

• multiple chemical sensitivity (see Ashford, N.A. and Miller, C.S. Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• reactive airway dysfunction syndrome (see Chest 88(3)376-384, 1985)
• reactive upper airway dysfunction syndrome (see Archives of Environmental Health 48(1)14-18, 1993)
• irritant associated vocal cord dysfunction (see Journal of Environmental and Occupational Medicine 40(2):136-142, 1997)
• chemical headache exposure syndrome (see Headache 22:555-559, 1993)
• reactive intestinal dysfunction syndrome (see Archives of Environmental Health 53(5):354-358, 1998)

See also :

• Brain, J.D. et al. (eds.) Variations in Susceptiblity to Inhaled Pollutants. Baltimore: Johns Hopkins University Press 1988.

Genetic make-up: Unknown. However, in people with a family history of neurological disease (Huntington's, Alzheimer's, Parkinson's) it may be especially prudent to avoid VOC exposure. Many are neurologically active substances capable of harming healthy nervous systems. It is not known if family history of neurological disease indicates genetic susceptibility to nervous system damage from environmental exposures.

Researchers have found genetic differences among individuals in their production and use of enzymes important to metabolizing foreign chemicals. Some of these differences appear to affect individual risk of developing certain cancers and certain nervous system diseases.

See:

• L.G. Costa and L, Manzo, Biomarkers in occupational neurotoxicology. In L. G. Costa and L. Manzo, Occupational Neurotoxicology. Boca Raton et al.: CRC Press 1998

Heavy metals [lead, mercury, others]: nasal congestion and inflammation, nosebleed, pharyngitis, cough, wheezing, worsening asthma, difficult breathing, severe lung disease, eye irritation, headache, dizziness, lethargy, fatigue, malaise, nausea, vomiting, anorexia, cognitive impairment, personality change, rashes, fever, chills, rapid heartbeat, retinal hemorrhage, muscle aches, hearing loss.

The unborn and very young: Greatest concern is neurological damage including cognitive and developmental deficits. Maternal lead exposures may cross the placenta and affect the unborn child, causing great harm to the fetus, though the mother is asymptomatic. Symptoms less severe than seizure (irritability, stomach pain, clumsiness, chronic learning deficits, reduced attention span) may be attributed to the wrong cause and thus exposures may continue. When symptoms are interpreted as 'just a stage' or 'just crankiness,' the child may continue to be exposed and to sustain continued damage. When symptoms are interpreted as hyperactivity or attention deficit disorder, the child may be given drugs that also affect the nervous system, while exposures continue unchecked and damage continues to occur.

Pregnant women: Nausea and loss of appetite may be attributed to 'morning sickness' thus allowing exposure to continue, and nutritional deficits to develop. Maternal nutritional deficits can have an adverse impact on both mother and child. Fatigue , headache, personality changes may be interpreted as psychological or hormonal, thus permitting exposure to continue.

The malnourished : Inadequate nutrition is known to favor the uptake of heavy metals, which are then stored in body tissues from which they can later be released.

The elderly: Fatigue, weakness, personality changes, headache, hearing loss, tremor, lack of coordination, constipation, lack of appetite, gastrointestinal discomfort may all be misattributed to 'aging.' Medications taken to treat symptoms may increase likelihood of adverse drug reactions, and do nothing to prevent ongoing exposures. Note that bone thinning processes release stored lead from the skeleton, thus providing an internal exposure source in the complete absence of an environmental source of exposure. Nausea, immobility, lack of appetite , poor diet may all contribute to liberation of stored lead within the body.

The chronically ill: See entry above, the elderly. Note that symptoms of heavy metal poisoning resemble the symptoms of other illnesses. In the chronically ill, symptoms may be interpreted as side effects of therapeutic drugs, worsening of the chronic condition, or psychological distress related to the chronic condition. Misattributions of this type can lead to increased medication and risk of adverse drug reactions, while exposures continue.

Genetic make-up: Lead induced disorders of heme (blood fraction) may be affected by genetic makeup.
Researchers have found genetic differences among individuals in their production and use of enzymes important to metabolizing foreign chemicals. Some of these differences appear to affect individual risk of developing certain cancers and certain nervous system diseases.
See: Cheng, Y. et al., Relation of nutrition to bonelead and blood lead in middle-aged to elderly men. American Journal of Epidemiology. 147:1162-1174, 1998.

What should we do about protecting susceptible people from harm due to poor IAQ?

Considering the numbers of people who may be susceptible to ill effects from indoor air pollutants, it is prudent for everyone who is responsible for activities that affect IAQ to regulate those activities with susceptible people in mind. This is particularly true in facilities where large numbers of potentially susceptible people congregate:

• schools (children, pregnant women)
• health care facilities (acutely and chronically ill people, children, pregnant women, the elderly)
• government offices administering programs to the disabled, elderly, poor, and young
• child and elder day care facilities

In addition, managers of places open to the general public should also bear susceptible people in mind when considering indoor environment management and maintenance activities. Such consideration can promote accessibility to the ill and infirm, create a healthy atmosphere for all visitors, prevent consumer complaints, and reduce potential liability.
It is important to mention that it is possible to institute good IAQ policies in facilities and workplaces in the absence of enforced federal standards. Such standards tell us what is legal. It is quite possible to use other standards, including enlightened self-interest, prudent avoidance, prevention and others, to guide decisions about what is wise.
No discussion of protecting the susceptible from indoor air pollution would be complete without a mention of the role of the home owner (or renter). Infants and children, the ill, and the elderly spend much of their time at home. Everyone spends many hours at home engaged in a single activity: sleeping Good home IAQ can protect the health of all occupants, including the susceptible. HEAL has many information resources available regarding least toxic, best management practices for promoting good home IAQ and preventing indoor home pollution.
Sources:

• Albers,J. Understanding gene-environment interactions. Environmental Health Perspectives 105(6): . 578-580. June 1997.
• Ashford, N.A. and Miller, C.S. Chemical Exposures: Low Levels and High Stakes. NY et al.: Van Nostrand Reinhold. 1998.
• Beasley, J.D. The Betrayal of Health. NY: Random House/Times Books, 1993.
• Brain, J.D. et al. (eds.) Variations in Susceptiblity to Inhaled Pollutants. Baltimore: Johns Hopkins University Press 1988.
• Cain, W.S. and J. Stevens, Uniformity of olfactory loss in aging. In C.Murphy et al (eds), Nutrition and the Chemical Senses in Aging: Recent Advances and Current Research Needs. Annals of the New York Academy of Sciences Volume 561, 1989. NY: New York Academy of Sciences .
• Y.Cheng et al., Relation of nutrition to bonelead and blood lead in middle-aged to elderly men. American Journal of Epidemiology. 147:1162-1174, 1998.
• Costa, L.G. and L. Manzo, Occupational Neurotoxicology. Boca Raton et al.: CRC Press 1998.
• Curtis, L. Fungi and their health effects. The Human Ecologist #73, Spring 1997.
• .EPA et al., Indoor Air Pollution, an Introduction for Health Professionals. (See HEALinks to IAQ on the Web.)
• EPA, Tools for Schools. (See HEALinks to IAQ on the Web.)
• Griffiths,T.D. and P.J. Meechan, Biology of aging. In Ferraro, K.F. Gerontology: Perspectives and Issues. New York: Springer, 1990.
• Ferris A.M. Et al., Effect of olfactory deficits on nutritional status. In C.Murphy et al. (eds), Nutrition and the Chemical Senses in Aging: Recent Advances and Current Research Needs. Annals of the New York Academy of Sciences Volume 561, 1989. NY: New York Academy of Sciences
• Hays, .S.M. et al., Indoor Air Quality: Solutions and Strategies.NY et al.: McGraw-Hill, Inc. 1995.
• Herzstein, J. Considerations of susceptible populations. In L. Rosenstock and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994
• Hoffman H.J. et al., Age-related changes in the prevalence of smell/taste problems among United States adult population. In C. Murphy (ed.), Olfaction and Taste XII: An International Symposium. Annals of the New York Academy of Sciences Vol. 855 NY: New York Academy of Sciences 1998.
• Kosta, L. Pesticides indoors (series). The Human Ecologist #60 Winter 1993, #61 Spring 1994, #62 Summer 1994.
• Kosta, L. Moisture indoors: an interview with Dennis Creech (Southface Institute). The Human Ecologist #70, Summer 1996.
• Kosta, L. Air fresheners and health: an Interview with Rosalind C. Anderson. The Human Ecologist #67 Fall, 1995.
• Kosta, L. Post-flood health risks. The Human Ecologist, June 1997 (#74)
• J. Krohn, Detoxification pathways. The Human Ecologist #80, Winter 1998. cf. S. E. Manahan, Toxicological Chemistry. Chelsea MI: Lewis Publishers 1992.
• Muilenberg, M and Burge, H. Aerobiology. Boca Raton FL: Lewis Publishers.1996.
• Rosenstock,L. and M.R. Cullen. Textbook of Clinical Occupational and Environmental Medicine. Philadelphia et al.: W.B. Saunders Company 1994
• Sturgis, P. Dust mite remediation The Human Ecologist (in press).
• Upton, A.C. and E.Graber, Staying Healthy in a Risky Environment. NY et al.: Simon & Schuster. 1993.
• Weinhold, R. Beginning research on genetic vulnerability to environmental toxins. The Human Ecologist 78, Summer 1998.
• Zeller, J. Drug induced deficiencies are widespread and treatable. American Druggist 8:53, 1998

At a Glance: IAQ on the Web