Gas, oil, coal, wood, and other fuels burned indoors consume valuable indoor oxygen unless air for combustion is supplied from the outdoors. In tight, energy efficient buildings, these fumes can cause serious health consequences.
Indoor combustion is found in fireplaces; woodstoves; gas-fired appliances such as ranges, clothes dryers, and water heaters; furnaces; gas — and kerosene-fired space heaters; and oil and kerosene lamps. Some of the potentially harmful emissions include nitrogen dioxide, nitrous oxide, sulfur oxides, hydrogen cyanide, carbon monoxide, carbon dioxide, formaldehyde, particulate matter, and hydrocarbons from natural gas fumes such as butane, propane, pentane, methyl pentane, benzene, and xylene. The indoor levels of these pollutants are determined by the amount of fuel burned and the rate of exchange with outdoor air.
What are some of the potential health
effects of combustion byproduct gases? In a study of 47,000 chemically sensitive patients, the most important sources of indoor air pollution responsible for generating illness were the gas stove, the improperly vented hot water heater, and the furnace.2 Hazardous fumes can leak at the pipe joints and remain undetected, especially if they occur under flooring. In addition, every pilot light adds fumes, and the burning process itself releases fumes into the air. The primary effects of exposure to gas fumes are on the cardiovascular and nervous systems, but they can affect any organ of the body. Some of the earliest symptoms from exposure to gas fumes include depression, fatigue, irritability, and inability to concentrate.
Carbon monoxide is commonly produced during incomplete combustion, especially from gas-fueled appliances. Carbon monoxide quickly diffuses throughout the entire house. Typically, these appliances must be removed from the homes of chemically sensitive patients to restore their health. Chronic exposure can result in multiple chemical sensitivities because carbon monoxide has the ability to interfere with the detoxification pathways in the liver, allowing the accumulation of toxic substances. Other effects of chronic carbon monoxide exposure include heart arrhythmia, decreased cognitive abilities, confusion, and fatigue.
Carbon dioxide is produced from burning natural gas. Elevated levels result in decreased mental acuity, loss of vigor, and fatigue. Nitrogen oxides are also released from gas appliances. A major source of contamination is the gas stove, particularly older models with pilot lights. These gases are known to impact the nervous and reproductive systems.
Coal, gas, and woodburning fireplaces that are not equipped with sealed doors emit particulate matter as well as toxic fumes. They also consume indoor oxygen unless fresh outdoor air is supplied to them. Particles not expelled by blowing or sneezing can find their way into the lungs, where they can remain for years.
It is important to mention that when an automobile is parked or operated in an attached garage, gas, oil, and other volatile organic compounds diffuse into the structure and will affect air quality in the home. Garages therefore must be properly isolated from the main structure.
Well-ventilated and well-sealed sources of combustion can be operated with very little degradation of the indoor air. However, even sources of minimal exposure must often be removed from the homes of chemically sensitive patients to restore their health.
Although some pesticides may technically be considered VOCs, these often odorless and invisible substances have become such a health threat that they warrant a separate discussion. Pesticides, or biocides, are poisons designed to kill a variety of plants and animals such as insects (insecticides), weeds (herbicides), mold (mildewcides), and fungus (fungicides). They were first developed as offshoots of nerve gas used during World War II. Most pesticides are synthetic chemicals made from petroleum. They are composed of active ingredients — the chemical compounds designed to kill the target organism — and inert ingredients — chemicals that deliver the active ingredients to the target, preserve them, or make them easier to apply.
Many people believe that the pesticides they buy, or those used by lawn and pest control companies, are “safe.” They assume that the government is protecting them; that pesticides are scientifically tested; that if used according to the instructions on the label they will do no harm; and that the products would not be on the market if they were unsafe. All of these assumptions are incorrect.
EPA registration does not signify pesticide safety.3 The EPA approves pesticides based on efficacy, not safety. Efficacy means the pesticide will kill the targeted pest. Out of the hundreds of active ingredients registered with the EPA, fewer than a dozen have been adequately tested for safety.4 In fact, it is a violation of federal law to state or imply that the use of a pesticide is “safe when used as directed.” When the