Studies of Childhood Exposure to Indoor Air Pollution

horizontal rule

Environmental Tobacco   Smoke
Volatile Organic Compounds
Nitrogen Oxides
Carbon Monoxide

horizontal rule


Most people are aware that outdoor air pollution can damage their health but may not know that indoor air pollution can also have significant effects. EPA studies of human exposure to air pollutants indicate that indoor air levels of many pollutants may be 2-5 times, and occasionally more than 100 times, higher than outdoor levels. These levels of indoor air pollutants are of particular concern because it is estimated that most people, including children, spend as much as 90% of their time indoors.

Over the past several decades, our exposure to indoor air pollutants is believed to have increased due to a variety of factors, including the construction of more tightly sealed buildings, reduced ventilation rates to save energy, the use of synthetic building materials and furnishings, and the use of chemically formulated personal care products, pesticides, and household cleaners.

In recent years, comparative risk studies performed by EPA and its Science Advisory Board (SAB) have consistently ranked indoor air pollution among the top five environmental risks to public health. EPA, in close cooperation with other Federal agencies and the private sector, is actively involved in a concerted effort to better understand indoor air pollution and to reduce people's exposure to air pollutants in homes, schools, and other environments where children live, learn, and play.


Environmental Tobacco Smoke (Secondhand Smoke)up_arrowBack to top

The Centers for Disease Control and Prevention's (CDC) National Center for Environmental Health reports that 43 percent of children, two months through 11 years of age, live in a home with at least one smoker. Children who live with smokers involuntarily inhale many pollutants in smoke. Environmental tobacco smoke (ETS), also known as secondhand smoke, is a complex mixture of more than 4,000 chemicals, including carbon monoxide , nicotine, tars, formaldehyde and hydrogen cyanide. Several of these chemicals are known human carcinogens or respiratory irritants.

Children exposed to ETS tend to have more bronchitis, pneumonia, respiratory infections, otitis media (fluid in the middle ear), and asthma symptoms. The frequency of infection depends directly on the amount of smoke in the home. Children who live with two smoking parents have more respiratory infections than children who live with one smoking parent. The lowest rates of respiratory infections and asthma are found in children of parents who do not smoke at all. Maternal smoking during pregnancy is associated with an increased incidence of Sudden Infant Death Syndrome.

EPA estimates that between 150,000 and 300,000 cases of lung infections, such as bronchitis and pneumonia, that occur annually in infants and young children up to 18 months of age may be attributed to exposure to ETS. Of these, 7,500 to 15,000 will result in hospitalization. ETS exposure aggravates the condition of between 200,000 and 1,000,000 asthmatic children. EPA has found that ETS increases fluid in the middle ear, a sign of chronic middle ear disease, the most common cause of hospitalization for surgery in children.

The CDC estimates that children exposed to tobacco smoke in their homes have 18 million more days of restricted activity, 10 million more days of bed confinement, and miss 7 million more school days annually than other children, primarily due to acute and chronic respiratory conditions.

Allergensup_arrowBack to top

Allergens, especially those containing biological matter, such as house dust mites, cockroaches, pet dander, pollen, molds, spores, bacteria, and viruses, are known to cause or aggravate asthma. Allergic reactions often combine with and seriously aggravate the symptoms of asthma, the common cold, pneumonia, and other conditions. Allergens also may cause eye, nose and throat irritation, shortness of breath, dizziness, lethargy, and fever.

Volatile Organic Compoundsup_arrowBack to top

Volatile organic compounds (VOCs) are chemicals that can volatilize (evaporate) from substances, such as cleaning products, adhesives, paints, dry-cleaning fluids, and wood preservatives. VOCs can be emitted from these products into the air and may be trapped indoors, especially in tightly sealed buildings. An EPA study of six communities in various parts of the United States found that indoor levels of VOCs are up to ten times higher than outdoor levels. Symptoms of VOC exposure may include eye, nose and lung irritation, rash, headache, nausea, vomiting, and asthma. Exposure to some VOCs, such as benzene and vinyl chloride, may cause cancer.

Formaldehydeup_arrowBack to top

Formaldehyde is a common VOC, is a colorless, strong-smelling gas used in pressed wood (particle board, fiberboard, and plywood), paints, coatings, cosmetics, fabrics, and insulation materials. Formaldehyde is released into the air from these products as well as from burning wood, kerosene, or natural gas, and from automobiles and cigarettes. Formaldehyde causes cancer in laboratory animals and is considered by EPA to be a probable human carcinogen. Although formaldehyde affects people differently, it may irritate the eyes, nasal sinuses, throat, and lungs, and may trigger asthma. Children and adults have developed allergic reactions, including hives, from exposure to the gas.

Nitrogen Oxidesup_arrowBack to top

Nitrogen Oxides are more often thought of as outdoor air pollutants emitted by motor vehicles and fossil-fuel burning power plants, but they also are found indoors. Inadequately vented gas ranges, gas pilot lights, gas or kerosene heaters, and welding activities, as well as tobacco smoke, contribute to nitrogen oxides in indoor air. Because they are potent respiratory irritants, they may aggravate asthma and other respiratory disease.

Carbon Monoxideup_arrowBack to top

Carbon monoxide is a colorless, odorless gas produced from the incomplete burning of virtually any combustible product. It may accumulate indoors as a result of tobacco smoking, poorly ventilated appliances, and attached garages. Carbon monoxide enters the blood from the lungs and combines with hemoglobin, blocking the blood's ability to carry oxygen to body cells. Symptoms of carbon monoxide exposure may mimic influenza and include fatigue, headache, dizziness, nausea and vomiting, mental confusion, and rapid heart rate. Depending on the level of exposure, carbon monoxide can be immediately fatal. Long-term, low-level exposure to carbon monoxide by pregnant women have the potential to injure the developing fetus.

Radonup_arrowBack to top

Radon, a known human carcinogen, is a naturally occurring, radioactive gas that is colorless, odorless, and tasteless. It comes from the natural decay of uranium, a radioactive metal found in soil and rock in the earth's crust all over the United States. Radon travels through soil and enters the indoor environments of buildings through cracks and other openings in the foundation. Eventually, radon decays into radioactive particles that can be inhaled and then trapped in the lungs. As these particles decay, they release small bursts of radiation that can damage lung tissue and lead to lung cancer later in life.

EPA estimates that radon may cause from 7,000 to 30,000 lung cancer deaths in the United States each year. Radon is the second leading cause of lung cancer deaths in adults, after smoking. An individual's risk of getting lung cancer from radon depends mainly on three factors: the level of radon, duration of exposure, and smoking habits. Risk increases in individuals exposed to high levels of radon over a long time. The risk of dying from lung cancer caused by radon is much greater for smokers than for non-smokers.

Leadup_arrowBack to top

Exposure to lead-contaminated dust, is the most common way to get lead poisoning. Lead is highly toxic and exposure to it can be dangerous, especially for children who are 6 or younger. The most common household lead hazards are lead-based paint, lead dust, and contaminated soil. Other sources of lead hazards are older plumbing fixtures, vinyl miniblinds, painted toys and household furniture made before 1978 that may be painted with lead-based paint, lead smelters or other industries can release lead into the air and lead-glazed ceramic ware, pottery, and leaded crystal can contaminate food and liquids stored in them.

Lead is poisonous because it interferes with some of the body's basic functions. Exposure to low levels of lead can permanently affect children. In low levels, lead can cause nervous system and kidney damage. Learning disabilities, attention deficit disorder, and decreased intelligence. High levels of lead can have devastating effects on children, including seizures, unconsciousness, and, in some cases, death.

Pesticidesup_arrowBack to top

According to a recent survey, 75 percent of U.S. households used at least one pesticide product indoors during the past year. Products used most often are insecticides and disinfectants. Another study suggests that 80 percent of most people's exposure to pesticides occurs indoors and that measurable levels of up to a dozen pesticides have been found in the air inside homes. The amount of pesticides found in homes appears to be greater than can be explained by recent pesticide use in those households; other possible sources include contaminated soil or dust that floats or is tracked in from outside, stored pesticide containers, and household surfaces that collect and then release the pesticides. Pesticides used in and around the home include products to control insects (insecticides), termites (termiticides), rodents (rodenticides), fungi (fungicides), and microbes (disinfectants). They are sold as sprays, liquids, sticks, powders, crystals, balls, and foggers. In 1990, the American Association of Poison Control Centers reported that some 79,000 children were involved in common household pesticide poisonings or exposures. In households with children under five years old, almost one-half stored at least one pesticide product within reach of children. Exposure to high levels of cyclodiene pesticides, commonly associated with misapplication, has produced various symptoms, including headaches, dizziness, muscle twitching, weakness, tingling sensations, and nausea. In addition, EPA is concerned that cyclodienes might cause long-term damage to the liver and the central nervous system, as well as an increased risk of cancer.