INDOOR AIR POLLUTION

Rising energy costs during the past 30 years have led to increased insulation and decreased ventilation of homes, which elevates the level of indoor air pollutants. The health hazards of

environmental tobacco smoke have already been discussed. Other sources of indoor air pollutants are gas cooking stoves and furnaces, wood stoves, construction materials, furniture,

radon, allergens associated with pets, dust mites, and fungal spores and bacteria. The major categories of indoor air pollutants and their health effects are summarized in Table 9-11 and

discussed briefly next.[36]

Carbon Monoxide.

This odorless, colorless gas is a byproduct of combustion produced from burning gasoline, oil, coal, wood, and natural gas. It is also a major pollutant in tobacco smoke, and its untoward

effects were discussed earlier along with cigarette smoking. Here we should note that carbon monoxide levels in ambient air should not exceed 9 ppm; however, indoor levels of 2 to 4 ppm

have been measured in homes during the winter. Such carbon monoxide pollution of indoor air can reduce exercise capacity and aggravate myocardial ischemia. Higher levels can cause

poisoning manifested as headaches, dizziness, loss of motor control, and coma. Approximately 900 accidental deaths due to asphyxia are caused by indoor carbon monoxide pollution each

year in the United States.

Nitrogen Dioxide.

Gas stoves and kerosene space heaters can raise indoor levels of nitrogen dioxide to 20 to 40 ppm in homes; this is several orders of magnitude higher than outdoor air levels. Children are

more susceptible to the untoward

TABLE 9-11-- Health Effects of Indoor Air Pollutants

Pollutant Populations at Risk Effects

Carbon monoxide Adults and children Acute poisoning

Nitrogen dioxide Children Increased respiratory infections

Wood smoke Children Increased respiratory infections

Formaldehyde Adults and children Eye and nose irritation, asthma

Radon Adults and children Lung cancer

Asbestos fibers Maintenance and abatement workers Lung cancer, mesothelioma

Manufactured mineral fibers Maintenance and construction workers Skin and airway irritation

Bioaerosols Adults and children Allergic rhinitis, asthma

Data from Lambert WE, Samet JM: Indoor air pollution. In Harber P, et al (eds): Occupational and Environmental Respiratory Disease. St. Louis, Mosby-Year Book, 1996, p. 784; and

Menzies D, Bourbeau J: Building-related illnesses. N Engl J Med 337:1524, 1997.

effects of nitrogen dioxide. It impairs lung defenses and is hence associated with increased respiratory infections.

Wood Smoke.

This is a complex mixture of nitrogen oxides, particulates, and polycyclic aromatic hydrocarbons. High concentrations of wood smoke in poorly ventilated homes can increase the

incidence of respiratory infections in children.

Formaldehyde.

This highly soluble, volatile chemical has been used in the manufacture of many consumer products, including textiles, pressed wood, furniture, and urea formaldehyde foam insulation.

Although indoor levels are usually less than 1 ppm, it can cause acute irritation of the eyes and upper respiratory tract and exacerbation of asthma. Formaldehyde is frequently emitted with

acrolein and acetaldehyde, which may have additive or synergistic irritant effects. Additional volatile organic compounds that may be present at low levels in indoor air include benzene,

tetrachloroethylene, polycyclic aromatic hydrocarbons, and chloroform. The potential for toxicity or carcinogenicity at these exposure levels is low, although occupational exposure to

these volatile compounds can be hazardous. Formaldehyde at high doses (6 to 14 ppm) has produced nasal tumors in rats.[37]

Radon.

Radon, a radioactive gas, is a decay product of uranium widely distributed in the soil. Radon gas emanating from the earth is prevalent in homes. Indoor levels of radon average around 1.5

pCi/L; approximately 4% of homes have an annual average level greater than 4 pCi/L. Radon gas is inhaled into the lungs; its decay products emit alpha radiation, which has been

associated with lung cancer in miners. According to some estimates, the low levels found in indoor air account for 10,000 lung cancers per year in the United States.[38]

Asbestos Fibers.

Homes and public buildings built before the 1970s in the United States contain asbestos insulation, pipe covers, ceiling tiles, and flooring. If these materials are non-friable and

undisturbed, low levels of fibers can be measured in indoor air. Maintenance and abatement workers who repair or remove asbestos-containing materials are at risk for lung cancer and

mesothelioma if they do not use respirators. [39] [40]

Date: 2016-04-22; view: 674