Medical Issues

Asthma, Mold, Allergens

Poor Indoor Air Quality Causes Serious Health Issues

Facts About Health Problems and your Indoor Environment

▪ People spend more than 90% of their time indoors.

▪ Indoor air is up to 5 times more polluted than outside air.

▪ EPA has ranked indoor air quality as one of the top 5 environmental health risks.

▪ Asthma has increased 160% in the past 15 years.

▪ 50 percent of all illnesses are either caused or aggravated by poor indoor air quality.

▪ Indoor levels of air pollutants can be 2-5 times higher, and occasionally 100 times higher, than outdoor levels

▪ Over 20 million Americans have asthma including over 6 million children and increasing.

▪ Asthma accounts for over 14 million loss workdays.

-More than 60% of hospitality facilities (restaurants, hotels, etc.) work places and schools in the US have poor IAQ.

Mold Illness

Mold is a type of fungi that can grow in damp or humid environments. While some types of mold are harmless, others can cause serious health problems when inhaled. People with allergies, asthma or compromised immune systems are especially at risk for developing health problems related to mold exposure.

Symptoms of mold-related illness can vary depending on the type of mold and the length of exposure. Some common symptoms include:

  • Respiratory problems such as coughing, wheezing, and difficulty breathing
  • Allergic reactions such as sneezing, watery eyes, and skin rash
  • Nasal congestion and sinus irritation
  • Headaches and dizziness
  • Irritation of the eyes, skin, nose, or throat
  • Tiredness or Lethargy
  • Depression, Mood Changes

If you suspect that you or a loved one may be experiencing health problems related to mold, it is essential to see a doctor or other healthcare professional. They will be able to assess your symptoms and determine the appropriate course of treatment.

If you believe that mold may be the cause of your health problems, it is also important to have your home or workplace inspected for the presence of mold. A professional mold inspection can identify the type and location of any mold present and recommend appropriate remediation measures.

If you are concerned about the health risks of mold and want to take steps to protect yourself and your family, it is important to keep your home or workplace well-ventilated and free of excess moisture. This can help prevent the growth of mold and reduce the risk of exposure to potentially harmful fungi.

If you have questions or concerns and would like to have your home or workplace checked for mold, please call us at


Additional IAQ Information

The following is a brief summary of common indoor air pollutants, their sources, potential health effects and acceptable mitigation measures. Pollutants included are:

Molds and Allergens
Tobacco smoke (ETS)
Combustion by-products
Household chemicals

Microorganisms, Allergens and Mold

Mold, becomes a problem inside a home or business when there’s excessive humidity or moisture for an extended period of time. The problem can originate from sudden water releases, like a burst pipe or large spill that goes untreated, or from a chronic condition, such as a leaking roof or plumbing. Even high humidity or warm, moist air condensing on cool surfaces can trigger mold problems. It’s always best to have the mold evaluated by a certified professional. 

Mold can grow almost anywhere in a home or business if conditions permit. If there is visible growth on painted wall surfaces, property owners should be concerned about what may be growing on the wall’s opposite side. The environment inside the walls of a house often differs drastically from the outside and could create a perfect haven for mold. If the wall remains wet for a prolonged period, it’s almost guaranteed that the mold growth on the back side will be worse than on the front. At that point, containing the work space and removing moldy materials, followed by cleaning of salvageable framing, are the best options.

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What Type of Organism is Mold ?

Molds are the most typical form of fungus found on earth, comprising approximately 25% of the earth’s biomass. Other fungi include yeasts and mushrooms. Molds are ubiquitous on our planet and are essential decomposers of organic substances necessary for sustaining plant and animal life. Molds are made up of masses of filament-like cells called hyphae. Under the appropriate conditions, the hyphae will grow into long intertwining strings that form the main body of the fungus, or the mycelium. It is the mass of mycelium that is visible to the human eye. Molds reproduce via spores. However, molds can also spread if a fragment of broken hyphae is transplanted to an area with adequate moisture and organic matter for food.What causes mold to grow? Molds reproduce through the production of spores. The environment in which a given mold may grow prolifically is very likely different from the environment necessary for spore production. After the spores are formed they are released into the air to be carried elsewhere for germination and growth. Mold spores can survive for many years in dry or hot environments, requiring only moisture and available organic matter to allow them to germinate.
California Research Bureau, California State Library

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What are “Toxic Molds” ?
Journalists have used the term “toxic mold” when writing about molds that have been implicated in severe health reactions in humans. As used in the press, this term generally refers only to those molds capable of producing mycotoxins. However, all molds under proper conditions are capable of eliciting a negative health response in humans through other methods such as inflammation, allergy, or infection. Therefore, limiting the discussion to just those molds that potentially produce mycotoxins is inappropriate.

Properties of Molds Which Potentially Pose a Threat.
Molds can elicit a variety of health responses in humans. The severity of the impact depends upon the type and amount of mold present as well as the susceptibility and sensitivity of the individual experiencing mold exposure. Humans are exposed to molds via ingestion, inhalation, and skin contact with mold or mold infested material. Although molds are living, multiplying organisms, they do not have to be alive to cause adverse health effects. Below is a list of mold components known to elicit a response in humans.

Volatile Organic Compounds.
In the paper “Fungi & Indoor Air Quality” Sandra McNeel and R. Kreutzer state that “[m]olds produce a large number of volatile organic compounds. These chemicals are responsible for the musty odors produced by growing molds.” Volatile organic compounds also provide the odor in cheese, and the “off” taste of mold infested foods. Exposure to high levels of volatile organic compounds, from any source, such as industrial work places, can irritate the mucous membranes and affect the central nervous system, producing such symptoms as headaches, attention deficit, inability to concentrate, and dizziness. According to McNeel, at present the specific contribution of mold volatile organic compounds to building-related health problems has not been studied. Also, mold volatile organic compounds are likely responsible for only a small fraction of total volatile organic compounds indoors.

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Due to the presence of allergens on spores, all molds studied to date have the potential to cause an allergic reaction in susceptible humans. Allergic reactions are believed to be the most common exposure reaction to molds. These reactions can range from mild, transitory responses, like runny eyes, runny nose, throat irritation, coughing, and sneezing; to severe, chronic illnesses such as sinusitis and asthma.

Some molds are capable of producing mycotoxins, natural organic compounds that are capable of initiating a toxic response in vertebrates. Molds known to potentially produce mycotoxins and which have been isolated in infestations causing adverse health effects include certain species of Acremonium, Alternaria, Aspergillus, Chaetomium, Cladosporium, Fusarium, Paecilomyces, Penicillium, Stachybotrys, and Trichoderma. This list is not all-inclusive.*

While a certain type of mold or mold strain type may have the genetic potential for producing mycotoxins, specific environmental conditions are believed to be needed for the mycotoxins to be produced. In other words, although a given mold might have the potential to produce mycotoxins, it will not produce them if the appropriate environmental conditions are not present.

Currently, the specific conditions that cause mycotoxin production are not fully understood. The United States Environmental Protection Agency (U.S. EPA) recognizes that mycotoxins have a tendency to concentrate in fungal spores and that there is limited information currently available regarding the processes involved in fungal spore release. As a result, the agency is currently conducting research on Stachybotrys chartarum in an effort to determine “the environmental conditions required for sporulation, emission, aerosolization, dissemination and transport of [Stachybotrys] into the air.”

Potential Health Effects of Molds
Many different organisms are known to cause infection and many more can produce allergic responses in man. The inhalation of biological aerosols from people and animals is the primary means of contracting respiratory infections, although air-cooling equipment, humidifiers, cool-mist vaporizers, and nebulizers can also incubate and distribute bacterial aerosols indoors and could be a source of infection.

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According to the National Health Survey, respiratory illnesses are responsible for more than half of all acute conditions. Pollen, molds, dust mites, animal dander, algae, and insect parts are known allergens. The effect of these antigens in the asthmatic and allergic individual has been well-defined.

Certain health effects, such as those related to allergic reactions like irritation of the eyes, nose, and throat, dermatitis, exacerbation of asthma, and respiratory distress, have been proven to be associated with mold exposure. Other reported effects such as fever, flu-like symptoms, fatigue, respiratory dysfunction (including coughing up blood), excessive and regular nose bleeds, dizziness, headaches, diarrhea, vomiting, liver damage, and impaired or altered immune function have been identified in persons who have been exposed to mold via inhalation, however, limitations in existing science hinder the ability of researchers to conclusively cite mold exposure as the cause of these health effects. Similarly, while kidney damage, infertility, reproductive cycle disruption, and neurotoxicity have been reported in animals exposed to molds under laboratory conditions, no evidence of these effects has been noted in humans.

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A large variety of biological material is present in the indoor environment.  Sources include virtually everything indoors, but mainly people, animals, plants, and insects.
Control Methods

Many illnesses, including respiratory illnesses, appear to be transmitted primarily from person-to-person. Overcrowding, reduced ventilation, and increased use of untreated recirculated air have a potential to increase concentrations of microorganisms and allergens. There is limited data establishing a correlation between acute respiratory disease and ventilation rates. More common control methods for preventing transmission of illnesses include less crowded living conditions, isolation of infected individuals, and vaccination.

Temperature and humidity conditions are important for many microorganisms, allergens, and molds. Molds need available water to grow. Studies have shown a relationship between respiratory infections and low or high relative humidity. Studies have also shown that the survival or infectivity of microorganisms and allergic mite and fungal populations is directly dependent on relative humidity. These studies suggest that maintaining a relative humidity between 40 to 60 percent indoors would minimize adverse health effects from microorganisms and allergens by reducing their indoor populations. Many of the microorganisms and allergens are also dependent on suitable temperatures to survive.

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For the sensitive individual with allergies, dust control methods (air-cleaning devices) are recommended to reduce the concentration of potential allergens in the home. However, it is important to realize the efficiency and effectiveness of these devices differ and that they should not be used without other environmental control methods. Recent reports have questioned the ability of these units to significantly reduce symptoms because allergens of most concern, such as animal allergens, mite fecal pellets, and pollens quickly settle to the floor and, therefore, are not removed by air cleaning. Some studies have indicated that air conditioning alone is as effective as specialized air cleaning devices. This is most likely related to the control of relative humidity and the resulting control of microbial, mite, and fungal populations.

The first step to controlling mold growth involves stopping all available water sources. Quick drying of wet materials is next and should be accomplished within 24 hours. The smell of mold and visible mold growth are indications of a problem and testing is recommended. A full investigative inspection should be performed by an Indoor Environmental Professional.

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How to improve your IAQ
Source Control – eliminate individual sources of pollution or reduce their emissions.

Improved Ventilation – increase the amount of outdoor air coming indoors.

Air Cleaners – continious use of an air cleaner that captures and destroys harmful particles and microorganisms.

Regular HEPA vaccuum – minimum once a week.

Replacement air filters – for heating, cooling and air cleaning systems.

Clean and maintain -A/C and heating duct work.

***Note: Some information contained on this page was found at

Formaldehyde (HCHO) is a colorless, flammable gas with a pungent suffocating odor. It is the most important aldehyde produced commercially, and is used in the preparation of urea-formaldehyde and phenol-formaldehyde resins. It is also produced during the combustion of organic materials and is a component of smoke.

Health Effects of HCHO
Health effects associated with exposure to HCHO fall into several categories. These include: irritant effects, sensitization, and carcinogenicity.  HCHO is intensely irritating to the mucous membranes, which includes the eyes and respiratory tract. Common symptoms from exposure to HCHO include: burning eyes, nose, and throat; headache; and nausea. HCHO has the potential to sensitize exposed individuals, which can involve both asthma symptoms and skin reactions. Some people exposed to HCHO will develop asthma symptoms. These symptoms include wheezing and chest congestion. Urticaria (a skin condition marked by intensely itching wheals usually caused by an allergic reaction) has been reported following inhalation of HCHO fumes. HCHO can be considered a sensitizing agent. Documentation of this effect has been seen in dialysis patients, as well as persons chronically exposed to low levels in mobile homes. HCHO has been designated as a probable human carcinogen, and has also been designated as a workplace carcinogen by the National Institute for Occupational Safety and Health (NIOSH).

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U.S. Occupational Safety and Health Administration and Washington State Department of Labor and Industries workplace regulations call for exposures which do not exceed 0.75 PPM as an eight hour time weighted average (TWA), with a 0.5 PPM action level, and a 2 PPM short-term exposure limit for 15 minutes. NIOSH recommends a 0.016 PPM eight hour TWA and a 0.1 PPM 15 minute ceiling. The American Council of Governmental Industrial Hygienist recommend a ceiling of 0.3 PPM.

No residential standard exists in Washington State. The American Society of Heating, Refrigeration, and Air Conditioning Engineers recommends a maximum continuous indoor air concentration of 0.1 PPM. Other states and several foreign countries have guidelines or standards for residential indoor air exposures which range from 0.1 to 0.5 PPM.

The odor threshold ranges from 0.05 PPM to 1 PPM.  At concentrations of 0.05 to 0.5 PPM HCHO produces a definable sensation of eye irritation. In occupational studies, reports of eye tearing, prickling, stinging, and burning are reported at levels from 0.13 to 2.7 PPM. Airway irritation has been reported as low as 0.1 PPM, but more commonly occurs in ranges of 1 to 11 PPM.

Symptoms range from the feeling of a dry throat, tingling of the nose, to a sore throat. However, airway irritation (at concentrations of 5-30 PPM) is characterized by cough, chest tightness, and wheezing. Chronic industrial exposure to concentrations ranging from 0.5 to 8.9 PPM produce changes in the nasal and pharyngeal mucosa, and complaints of throat irritation, diminished sense of smell, and dryness of the throat. HCHO has been associated with both the development of asthma and the initiation of asthma attacks. High levels (50-100 PPM) have been associated with swelling of the lung and movement of fluid into the lung, as well as pneumonia. Exposures to levels greater than 100 PPM can be fatal.

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The major sources in residential settings are building materials. These products may contain phenol, urea, thiourea, or melamine resins which contain HCHO. HCHO has also been used in the paper, photographic, and clothing industries. It is used in the finishing of all permanent press material, and can be found in the glues used in furniture construction, or carpet and vinyl attachments.
Urea-formaldehyde resin containing products are the most common HCHO source in the home. This formulation is approved for interior grade materials such as plywood, hardwood cabinetry, and wall paneling. Urea-formaldehyde resins release trapped free HCHO, as well as HCHO resulting from chemical degradation. Degradation of HCHO resins can occur when these materials become damp from exposure to high relative humidities, or if the HCHO materials are saturated with water during flooding, or when leaks occur. The release of HCHO occurs when the acid catalysts involved in the resin formulation are reactivated. Levels of out-gassing can also increase with increasing temperatures and relative humidity.

Control Methods
The prevention of problems associated with exposure to HCHO are best treated by source control. The selection of HCHO free or low-emitting products such as exterior grade plywood which use phenol HCHO resins for indoor use is the ideal starting point.

Alternatives to source control include: filtration, sealants, and fumigation treatments. Filtration can be achieved using selected adsorbents. Sealants involve coating the materials in question with two or three coats of nitro-cellulose varnish, or water based polyurethane. Three coats of these materials can reduce out-gassing by as much as 90 percent. Professional carrier gas treatment with ammonia will also minimize HCHO out-gassing.

Testing for HCHO can be accomplished with passive monitors, real time active monitors, or colorimetric sorbent tubes. Passive monitors can be purchased through industrial hygiene suppliers or through independent contractors who manufacture their own monitors. For listings in your area, refer to your telephone book under analytical laboratories or environmental services.

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Asbestos,is the generic name for several fibrous minerals. The three main types are chrysotile (white), crocidolite (blue), and amosite (brown).  Asbestos’ characteristics of flexibility, strength, incombustibility, and durability resulted in its widespread use between the 1920s and mid 1970s. Chrysotile asbestos accounts for approximately 95 percent of all asbestos used and is anticipated to be less pathogenic than the amphibole type asbestos products.

Asbestos-containing materials may be present in many household products manufactured before 1977, as well as in many areas in and around the home. Some of the more common locations are old pipe and furnace insulation, vinyl floor tiles and vinyl sheet flooring, patching compounds and textured paints, brake and clutch pads, roofing materials, home siding, some 1930-1950 wall and ceiling insulations, some decorative ceiling materials, and other items requiring the characteristics of asbestos.

Health Effects
Asbestos exposure has been shown to cause cancer of the lung; a rare cancer of the chest and abdominal lining called mesothelioma; and cancers of the esophagus, stomach, colon, and other organs. It can also cause a noncancerous chronic and debilitating lung disease called asbestosis. Asbestosis is related to lengthy exposure to high levels of asbestos fibers as was common in some industrial environments during the 1920s to the 1940s. Asbestosis is not considered a significant outcome from incidental nonoccupational exposure. The amount of exposure necessary to cause disease is unknown and is probably different for different population subgroups. Asbestos-related diseases generally do not appear for 15-35 years after first exposure. This length of time between first exposure and onset of disease appears to be related to the amount and duration of exposure. However, it is believed that any exposure to asbestos involves some health risk. No safe level of exposure has been established.

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Asbestos and cigarette smoking combined significantly increase the potential for lung cancer. Studies have shown asbestos workers who smoke have a risk of lung cancer eight times greater than smokers in the general population. This same group has a lung cancer risk 92 times greater than unexposed nonsmokers.
The presence of asbestos in the home alone does not necessarily mean there is an exposure problem. Asbestos is hazardous if inhaled and this usually occurs only when asbestos-containing materials have been damaged and there is a release of asbestos fibers. Of greatest concern are asbestos products that are friable (this means easily crumbled, pulverized, or powdered by hand). Unless the material is crumbling, needs repair, or must be removed, it is recommended that it not be disturbed. Improper removal and handling can release high levels of fibers into the air that then become a continual source of exposure.

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Control Methods
Asbestos control methods generally include source removal or source modification. Small minor repairs can often be taken care of by duct tape or other commercial products which seal the damaged area. Heat resistant paints and sealers are also sometimes suitable for small repairs. These products are often available through commercial paint and safety supply outlets.
Removal should be done only when necessary.

Although current law permits a homeowner to perform their own removal work, it is recommended that removal work be done only by contractors with highly-trained workers who are required to be certified by the Washington State Department of Labor and Industries. These workers are knowledgeable about the permits that must be obtained, safe removal practices, necessary protective equipment, and proper disposal methods.

Homeowners choosing to do their own removal must first notify their local air pollution control authority. They may also be required to notify their local health department and other    local government agencies. Information regarding proper removal practices, protective equipment, and disposal can be obtained through local health departments, local air pollution control authorities, and the Department of Labor and Industries.

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Radon gas is a chemically inert, odorless, colorless, and tasteless naturally-occurring radioactive element found in soils and rocks that make up the earth’s crust. It comes from the normal decay of radium. Because it is a gas, it can easily move through soil and water and enter the atmosphere. Radon gas has a half-life approximating four days, after which it decays into four daughter products. These solid decay products are not inert and often attach themselves to airborne particulates which may then enter the lungs. These particles with attached radon daughters may become lodged in the lungs where the radon daughters undergo rapid decay, emitting radiation that damages lung tissue.

In the Northwest, the major source of radon gas in the home is the soil beneath and surrounding the residence. Common entry routes are through cracks in concrete slabs; cracks between poured concrete slabs; and blocks, pores and cracks in concrete blocks, slab footing joints, and mortar joints; loose fitting pipes; sump pits; and floor drains. Houses built on foundations with a ventilated crawl space should have few problems. Houses with basements and those built directly on or in the ground have a higher potential for problems.

Concentrations of radon and its daughter products are usually measured in pico-Curies per liter (pCi/l). The current action level (the level at which you should consider modifications) is 4 pCi/l. The Bonneville Power Administration, in cooperation with the WSU cooperative extension service and local utilities, has measured radon in thousands of homes in Washington State. To date, levels have ranged from less than 1 to 103 pCi/l.  Most of the higher levels have been found in Northeastern Washington, due to the naturally occurring radium in the soil and rock. Western Washington does not appear to have significant radon levels, although exceptions have been found. Nationally, the average radon concentration is approximately 1 pCi/1. The only way to know about your house is to test.

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Health Effects
Like other radioactive materials, radon can cause cancer. Much of the knowledge of the health significance of radon and its progeny is based  on the analysis of the effects of high exposures on underground miners. Based on several studies and current knowledge, the National Academy of Sciences believe that radon and its progeny are harmful at all exposure levels, and increased lengths of exposure and higher doses will increase the risk of cancer. EPA has estimated that as many as 10 percent of lung cancer deaths in the U.S. may result from exposure to indoor radon.

Control Methods
Usually, radon reduction is fairly simple and inexpensive. Methods, in order of increased complexity and expense, are:
▪  Seal radon entry points with appropriate caulking material and cover sumps and drains.
▪  Improve basement or crawl space ventilation by increasing vent number, size, and/or using fans.
▪  Increase the air pressure in ground floor or basement area to reduce radon entry.
▪ Ventilate the area under the basement or slab (sub-slab depressurization) to reduce the amount of radon available to enter the home.
Additional information and brochures regarding radon, its prevalence, measurement, and control techniques can be obtained by calling 1.800.SOS.RADON.

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Tobacco Smoke (Some Vaping Particles)
Indoor tobacco smoke is a major contributor to airborne contaminants in the home and other indoor environments. Over 4,000 chemical compounds, of which 40 are known or suspected carcinogens, have been identified in tobacco smoke. Some of the more important  pollutants are carbon monoxide, acrolein, hydrogen cyanide, formaldehyde, nitrous oxides, pyrene, nicotine, cadmium, and numerous carcinogenic polycyclic aromatic hydrocarbons. Environmental tobacco smoke (ETS), or the smoke that comes directly from burning tobacco, has up to 50 times the concentration of some carcinogenic compounds as does mainstream or exhaled smoke, because of the lower combustion temperature. ETS contributes approximately 90 percent of the total products of combustion from a cigarette.
Tobacco smoke is also the major source of respirable suspended particulates (RSP). Wood smoke, unvented gas appliances, and kerosene heaters also contribute to indoor RSP concentrations. Studies have shown that particulate concentrations in public buildings and homes where smoking is permitted often exceed EPA’s 24-hour outdoor air quality standard.

Health Effects
The health effects related to ETS exposure have only recently been investigated. The acute effects of involuntary smoking often depend on the individual being exposed. Principal acute effects can include: irritation of the eyes, nose and throat; coughing; headache; nausea; increased blood pressure; increased heart rate; and elevated carboxyhemoglobin levels. Passive smoking also affects several vulnerable subgroups of the population more than others. Many people with pre-existing health conditions, particularly those with asthma and other respiratory diseases, are often severely affected by exposure to ETS.

Many studies have shown adverse health effects to children of smokers. These studies have shown an association with increased respiratory illness and decreased pulmonary function. Infants and children under two years old seem particularly susceptible. Infants exposed to passive smoke also have triple the rate of sudden infant death syndrome compared to nonexposed infants. In children of smoking parents, other effects also reported include decreased attention and work capacity, increased developmental disability and respiratory problems, and decreased school attendance.
It has long been known that smoking increases the risks of lung, laryngeal, oral, esophageal, other organ cancers, and heart disease. The association between ETS exposure and cancer is clear  Increasing evidence indicates a high risk of lung cancer and heart disease for persons exposed to ETS. Several studies of nonsmoking wives of smoking husbands have found a statistically significant association between passive smoke exposure at home and risk of lung cancer. A recent study has reported that nonsmoking wives of husbands who smoke have three times the risk of heart attack than nonsmoking women married to nonsmokers. ETS may very likely be the most harmful indoor air pollutant.

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Control Methods

Only the prohibition of smoking assures a smoke-free environment. Other control methods generally consist of increasing ventilation, use of air cleaning devices, or the restriction of smoking.  For air cleaning devices to be effective, they must be large enough to circulate large volumes of air. Air cleaners, such as electrostatic precipitators, are only partially effective in that they remove only particulates and not the gases associated with tobacco combustion.

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Indoor Combustion By-Products
Indoor combustion of fuels can be a source of increased concentrations of gases and particulates. The major combustion by-products of concern are carbon monoxide (CO), nitrous oxides (NOx), and RSP. Other by-products may include sulfur dioxide, formaldehyde, carbon dioxide, hydrogen cyanide, and organic vapors. Common sources of indoor combustion by-products are unvented kerosene heaters, wood stoves, gas stoves, and tobacco smoke.

Carbon Monoxide
Carbon Monoxide (CO) is a colorless, odorless gas produced through incomplete combustion. CO is a poison that binds with hemoglobin, the oxygen-carrying molecule in human blood.  Because CO’s affinity to bind with hemoglobin is 250 times greater than oxygen, low airborne concentrations and long exposure times can result in substantial carboxyhemoglobin (COHb) concentrations in the blood. COHb is CO bound to hemoglobin. As COHb levels increase, less hemoglobin is available for the transport of oxygen. This lack of oxygen-carrying capability, which is indicated by the increase in COHb, results in the symptoms we associate with CO poisoning.

Health Impacts
The acute health effects of CO exposure are well established. Mild exposure symptoms may include headache, dizziness, decreased vigilance, decreased hand-eye coordination, weakness, confusion, disorientation, lethargy, chest pain (in cardiac patients), nausea, and visual disturbances. Greater or prolonged exposure can cause unconsciousness and death. The severity of symptoms depends on the concentration of CO, length of exposure, and degree of physical activity, as well as the state of health of the exposed individuals. People who are exposed to high CO concentrations for long periods of time during strenuous activity will reach the highest COHb levels.

Even low levels of CO can present a health risk to susceptible individuals, such as persons with heart disease, sickle cell disease, and anemia. Age and general health may also affect susceptibility to CO. Exposure to low levels of CO may harm the developing fetus.

Angina pectoris is chest pain associated with impaired oxygen flow to the heart and may occur at COHb levels between 2.5 and 4.9 percent in cardiac patients. In healthy individuals, decreased vigilance, confusion and disorientation, behavioral, and central nervous system effects occur at COHb levels between 4 and 6 percent. Remember that as symptoms of CO poisoning increase, you may become confused and less capable of making decisions that could save your life.

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Sources of Environmental Pollution

The National Ambient (outdoor) Air Quality Standard for CO is 9 PPM averaged over an eight hour period, or 35 PPM averaged over one hour. These standards are based on preventing adverse effects in individuals with cardiac or vascular disease and in exercising humans. Seattle, Spokane, Yakima, and parts of Pierce and Thurston counties may exceed these values during heavy traffic periods and when inversions occur. Inversions occur when cold stable air layers form above warmer air. This traps pollutants beneath the stable air layer. This can result in significant pollutant level increases, including CO. As outdoor levels increase due to peak traffic times, or because of an inversion, indoor levels will rise proportionately. If indoor sources of CO exist, indoor levels will be higher than those outside. Avoid strenuous physical activity during peak traffic times, in high volume traffic areas, and during inversions.

Indoor wood stoves, gas ranges, gas hot water heaters, gas and oil heaters, furnaces, and kerosene space heaters can all be sources of CO. Heating season is a time of particular concern with regard to CO exposure.  as and oil heaters that have not been used during the warm summer months should not be expected to perform efficiently without the benefit of service. It is imperative that furnaces be cleaned and serviced following the manufacturers instructions. Winter is also the time of year when people use space heaters. It is very important to use the correct grade of kerosene (1-K or manufacturers suggested grade).  Use of the incorrect grade of fuel will result in an increased production of CO.

Flame color is a good way to check the combustion of a fuel burning appliance. The flame should burn with a bright blue color. A yellow flame signals poor combustion and may indicate a problem with the flue or burner.  Ideally, combustion air for fuel burning appliances should not be drawn from inside the home. Some newer furnaces draw air from outside the home and this alleviates the possibility of back drafting. Fuel burning appliances which do not draw combustion air from outside the home are subject to back drafting, which occurs when flue gases, including CO, are drawn back through the flue into the living space in the home. This occurs because of an air pressure drop in the home resulting from high wind conditions or in tight homes when local exhaust fans are used without adequate make-up air. Back drafting may also be caused by blocked or partially blocked flues. Flues should be inspected regularly. If you suspect back drafting contact your furnace service representative or your fuel supplier.

Power outages are a time of higher risk. During power outages, people often resort to the use of kerosene space heaters, fire places, gas ranges, and even barbecues to heat homes. Do not use barbecues or gas ranges for a heat source. If unvented fuel burning space heaters are used for warmth, be sure that windows are opened slightly to provide fresh air into the living areas. Additionally, gas ranges should not be used without local exhaust, such as exhaust fans or vented hoods that are exhausted to the outside.

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Tobacco smoke, including second hand smoke, is a large source of CO in homes with smokers. Smokers have higher COHb values than nonsmokers and exposure to secondary tobacco smoke results in an increase in COHb values. Smokers generally have COHb values of five to six percent. Nonsmokers have COHb levels of 0.5 percent, whereas nonsmokers exposed to secondary tobacco smoke have been shown to have COHb levels in the two to three percent range.
Automobiles, Campers, RVs, and Boats

CO produced from cars left running in closed garages can accumulate and enter the home. Traveling in truck canopies and campers presents an especially high risk for children. The University of Washington and Virginia Mason have reported deaths and loss of consciousness and other signs of CO exposure in children in Washington State who were affected while riding in covered truck beds. CO will accumulate in this space because the shape of the truck produces turbulence, which can lower the air pressure in the truck bed, drawing exhaust into the covered area. No one should ride inside covered truck beds. Every year there are deaths associated with CO poisoning. The majority of these deaths are associated with motor vehicle exhaust (CO) leaking into cars, campers, and motor homes. Be sure to provide adequate ventilation. It is important that cars and trucks have a functional “tight” exhaust system.

To prevent or reduce exposure to CO, be sure to provide ventilation during fuel burning appliance use, do not run cars in closed garages, and maintain your car’s exhaust system. If your home has fuel burning appliances you may want to obtain a CO alarm. These units are very similar to smoke alarms and warn occupants when CO levels become unsafe. There are also several monitors available that change color during CO exposure. These are not very precise in indicating CO levels. The gas company will test your home for CO if you are a customer and suspect a gas leak, smell combustion fumes, or describe symptoms associated with CO exposure. If you suspect a problem with a gas appliance, contact your gas supplier.

If you think you have a problem, act immediately: leave, call from outside the home, and do not return to the home until the problem has been resolved.  Severe CO poisoning symptoms require emergency medical treatment.

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Nitrogen Oxides
Nitrogen oxides are highly toxic and irritating gases with a pungent odor.


The primary source for indoor nitrous oxides are gas burning appliances.

Indoor nitrogen dioxide (NO2) concentrations range between .03-.5 PPM with peak concentrations of .7 PPM having been measured in kitchens and other rooms of homes during conventional gas cooking and use of unvented gas appliances. EPA’s standard for outdoor air is 0.05 PPM. Generally, indoor concentrations do not exceed these standards, except during and shortly after use of unvented gas appliances.

Health Effects
Inhalation of nitrogen dioxide can induce effects similar to CO. Nitrogen oxides react with the blood’s hemoglobin, decreasing the blood’s oxygen-carrying capabilities and increasing cardiovascular stress. Nitrogen oxides can also produce temporary and long-term damage to bronchial airway and other lung tissues. Several studies, although not conclusive, have shown that children living in homes with gas appliances have elevated rates of minor respiratory illness and reduced respiratory function.

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Respirable Suspended Particulates

Respirable suspended particulates (RSP) are particles, organic and inorganic, that are suspended in the air and are small enough to be inhaled into the lungs.  RSPs are also often referred to as PM2.5 or as PM10s, particulate matter 2.5 microns or 10 microns in size or less.


The major source is tobacco smoke. There is increasing evidence that wood smoke is also a major contributor during the heating season. Unvented gas appliances and kerosene heaters also produce RSP.


There are no indoor standards for RSP. EPA has, however, established an annual average outdoor standard of 15 ug/m3 (micrograms per cubic meter), and a maximum 24-hour standard of 65 ug/m3 for PM 2.5’s. PM 10 standards are set at 50 ug/m3 for an annual average outdoor, and a maximum 24 hour standard of 150 ug/m3 for respirable particulates. As previously mentioned, these standards are often exceeded in indoor environments where smoking is permitted.

Health Effects

RSPs are comprised of many different compounds. Radon and benzo-a-pyrene, suspected carcinogenic agents, are transported by RSPs into the lungs. Gases or other substances may also be carried by RSPs into the lungs. Respiratory illness, especially chronic illnesses like bronchitis, emphysema, and asthma may be linked to, or aggravated by, exposure to RSPs.

Control Methods

Control approaches for these pollutants center on improving combustion efficiency of various household equipment such as gas ranges, kerosene heaters, wood stoves, or fireplaces, along with adequate ventilation and substitution.

RSPs, tobacco smoke, allergens and microorganisms are often considered similarly with respect to control methods (see sections on tobacco smoke and microorganisms and allergens).

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Household Chemicals

Many consumer products emit gaseous or particulate contaminants during their use or in storage. Consumer products, such as cleaners, waxes, paints, adhesives, detergents, paint strippers, dry cleaning agents, deodorizers, pesticides, solvents, and many home craft products can be sources of both organic and inorganic contaminants. Aerosols, which are widely used to package products such as cleaners, waxes, pesticides, polishes, paints, and adhesives, can be particularly important because they dispense the contents in a form that makes them readily available for direct inhalation. Each use of these products can release substantial quantities of particulates, solvents, and propellant. Additional sources for indoor volatile chemicals include plastics, textiles, building materials, and carpets which may release small amounts over long periods of time.

Health Effects

The wide variety of chemicals used in consumer products and materials precludes a discussion of specific household chemicals and their potential adverse health effects. The health risks associated with long-term exposure to the low levels commonly experienced in the indoor environment has not been investigated adequately. Willful abuse of aerosols and careless use of solvents in enclosed spaces have resulted in acute and chronic disorders and even death.

Control Methods

The primary means of control have been substitution and increased ventilation.  Increased awareness and concern by the public has resulted in manufacturers substituting less toxic chemicals in many consumer products and prompting them to make more products available in non-aerosol form. In addition, consumers are being more selective in the type of products they choose and how they are used.

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Pesticides are chemical or biological substances used to destroy, prevent, or control insects, vegetation, rodents, and other pest organisms. A 1976-77 EPA survey revealed that over 90 percent of U.S. households used pesticides and that over 80 percent of the households used them indoors. Twelve of the most commonly used pesticides were insecticides. Some of the most widely used pesticides are the disinfectants (anti-microbials). The study showed that over 90 percent of households use disinfectants in either the liquid or aerosol forms.

Use of pesticides in dwellings may be by the occupant or building maintenance staff who purchase an “off-the-shelf” product, or by a commercial pest control applicator. On occasion, the source of pesticide indoors may result from drift of the chemical from an outside application through open windows and doors. In addition to the direct application of pesticide in to household air, there are other sources which continually emit vapors into the living space. For example, the intrusion of chemical vapors from insecticides through the floors and walls from application to the crawl space and foundation of the dwelling, evaporation of residues from crack and crevice treatments to the interior of the building, and vapors from moth repellents and room deodorizers. In many areas pre- or post-construction treatment for carpenter ants or termite protection is undertaken. Some of these pesticides may persist in the home environment for many months or years after application. Chlordane (an insecticide of choice for termite and carpenter ant control) has been found to persist for over 20 years after treatment. Pesticides considered nonpersistent last much longer indoors, where they are protected from sunlight, water, and other factors which hasten their degradation.

Health Effects

The large variety of pesticides used in and around dwellings prohibits a discussion of specific symptoms and potential adverse health effects associated with each pesticide. The health risks associated with long-term inhalation exposure to low levels commonly experienced in the indoor environment has not been adequately investigated. In addition to pesticides themselves, approximately 1,200 inert ingredients are currently registered for use in pesticide formulations. These include solvents, propellants, emulsifiers, and adjuvants. Adequate toxicological data is available for only about one-third of these additives. The EPA has serious concerns about potential health effects associated with 120 of these additives. Proper interpretation of airborne pesticides values is very important. While there are occupational airborne pesticide permissible exposures levels (PEL), based on five 8-hour working days per week, these have limited value in the home situation. If residential values exceed the PEL, they would also be excessive for the home. However, if airborne pesticide values are below the PEL, for a given chemical, this does not mean they are safe for residential occupants. Full-time homemakers and small children may spend in excess of 21 hours per day inside the home, nearly three times the 8-hour shift. It has been recommended that a healthy adult living at home should not be exposed to more than one-fourth the work place PEL. In addition, an infant, elderly person, or someone who is ill may be more susceptible to the effects of small amounts.

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Control Methods

Corrective measures other than general improvement of IAQ is usually not warranted. Additional preventive measures are expensive and their success rate in lowering air concentrations is questionable. There are several ways to minimize exposure to indoor airborne pesticide levels:

▪ Increase the circulation of clean air in the house. When weather permits, periodically open windows and doors, and use fans to mix the air. In crawl spaces, clear or add vents and install a fan to constantly vent crawlspace air to the outside.
▪ Seal areas that directly contact treated soil, using grout, caulk, or sealant. Fill cracks in basement, ground floors, and walls, and openings around pipes, drains, and sumps
▪ Install a system that supplies outside air to appliances like clothes dryers and furnaces that now draw air from inside the house. Appliances that use indoor air may actually help draw vapors from the soil into the house through walls, floors, and basements.
▪ Check the condition of ducts in the crawlspace of the basement. Use duct tape to seal openings and joints

Additional Pesticide Assistance Information
Application of a pesticide by a commercial applicator or a private individual contrary to label instructions is termed a misapplication and is a violation of both state and federal regulations. Enforcement of pesticide regulations and investigation of pesticide misapplications are under the jurisdiction of the State Department of Agriculture . If you believe that a misapplication has been made and you wish to file a complaint, contact your State Department of Agriculture.

If you have questions regarding health effects, you can contact your local health department or this office at 888-547-5741. If you have symptoms which you believe are associated with a recent application, you should contact your physician or regional poison control center for advice. If you have a true medical emergency get help immediately .