EESA10H3 Chapter Notes - Chapter 2: Indoor Air Quality, Sulfur Dioxide, Nitrogen Dioxide
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22 Nov 2012
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Environmental Chapter 2: Urban
and Transboundary Air Pollution
•Much of what we currently understand about environmental lung disease
derives from the study of exposed workers since the Industrial Revolution
•Recognition of the relationship between nonworkplace air pollution and
respiratory disease dates back to the first use of coal as a combustion source
in the 14th century
-air pollution emergencies were caused by ait stagnation, which resulted in
greatly increased concentrations of atmospheric pollutants, especially
sulphur dioxide and suspended particulates
-worst episode occurred in London, where number of deaths reached 4000
•Since the atmosphere is dynamic and always changing, contaminants are
transported, diluted, precipitated, and transformed
•Air pollution knows no boundaries or nation borders
•Primary emissions of sulphur oxides, nitrogen oxides, carbon monoxide,
respirable particulates, and metals are severely pollution cities and towns in
Asia, Africa, Latin America, and Eastern Europe
•Relationship between air pollution and wealth; poorer countries (relying
heavily on coal) had significantly higher levels of total suspended particulates
(TSPs) than wealthier nations
•In nations that have reduced the primary emissions from heavy industry,
power plants, and automobiles, new problems have arisen from pollution by
newer industries and from air pollution caused by secondary formation of
acids and ozone
-the resulting high levels of air pollution (including indoor air pollution)
contribute heavily to the high mortality rates observed for acute respiratory
disease in children under the age of 5 in many developing countries
Defining Adverse Health Effects
•Adverse health effect; any effect that results in altered structure or impaired
function that represents the beginning of a sequence of events leading to
altered structure or function
Specific Air Pollutants Associated with Adverse
Respiratory Effects
•TABLE 2.1
Sulfur Dioxide and Acidic Aerosols
•Major sources of environmental pollution with sulphur dioxide are electric
power generating plants, oil refineries, and smelters
•Some fuels such as ‘soft’ coal are particularly sulphur-rich
•Sulphur dioxide released into the atmosphere does not remain gaseous; it
undergoes chemical reaction with water, metals, and other pollutants to form
aerosols
•Most common pollutants resulting from this atmospheric reaction are
sulphuric acid, metallic acids, and ammonium sulphates
•Smog; refers to the visibly cloud combination of smoke and fog
•Higher particle acidity was significantly associated with an inc
Particulates
•Particulate; particles suspended in the air after various forms of combustion
or other industrial activity
•‘fine’ particles produced almost exclusively from combustion sources have
been closely studied under the hypothesis that such small particles can
penetrate deeply into the lung, while larger particles would be trapped in the
upper airway
•Heart-rate variability (HRV); a measure of the cyclic variations of beat-to-beat
intervals and of the instantaneous heart rate
-evidence that reduced HRV is a risk factor for adverse cardiac events,
including angina, myocardial infarction (MI), life threatening arrhythmias, and
congestive heart failure
•Very high particulate levels measured in developing countries range up to
100 times the current US standard
•Deaths in children from acute respiratory disease are high when particulate
levels are high, even in nations with lower overall infant mortality
•After infant diarrhea, acute respiratory disease is believed to be the major
cause of death in children under the age of five in the developing world and