Environmental Engineering Reference
In-Depth Information
chapter three
Combustion-generated
contaminants
Indoor spaces are commonly contaminated with substances that result from
combustion. This has been the case since humans discovered the utility of
fire and attempted to use it under various levels of control to cook food and
provide warm living conditions in cold environments.
If fuels and materials used in combustion processes were free of con-
taminants and combustion were complete, emissions would be limited to
carbon dioxide (CO
O), and high-temperature reaction
products formed from atmospheric nitrogen and oxygen (NO
), water vapor (H
2
2
). However,
fuels and other combusted materials, e.g., tobacco, are never free of contam-
inants. Also, combustion conditions are rarely optimal; as a consequence,
combustion is usually incomplete. When burned, fuels such as natural gas,
propane, kerosene, fuel oil, coal, coke, charcoal, wood, and gasoline, and
materials such as tobacco, candles, and incense, produce a wide variety of
air contaminants. Some of these are generic to combustion while others are
unique to materials being combusted. Substances produced in most com-
bustion reactions include CO
x
, H
O, carbon monoxide (CO), nitrogen oxides
2
2
(NO
), respirable
particles (RSP), aldehydes such as formaldehyde (HCHO) and acetaldehyde,
and a variety of volatile organic compounds (VOCs); fuels and materials
that contain sulfur will produce sulfur dioxide (SO
) such as nitric oxide (NO) and nitrogen dioxide (NO
x
2
). Particulate-phase emis-
sions may include tar and nicotine from tobacco, creosote from wood, inor-
ganic carbon, and polycyclic aromatic hydrocarbons (PAHs).
Sources of combustion-generated pollutants in indoor environments are
many. In highly developed countries, they include emissions from: (1) a
variety of vented and unvented combustion appliances, (2) motor vehicles
(which may move from an outdoor [ambient] to an indoor environment),
and (3) fuel-powered machinery such as floor burnishers, forklifts, and
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