Pollutant Effects on Urban Population
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The effects of pollution can range from a little irritation to acute sickness or even death, according to the nature of the pollutant, concentration levels and the period of exposure.
To evaluate the effects of pollutants, two approaches are used:
Toxicological experimental studies using humans and animals; and
Epidemiological studies based on the measurable effects on a groups health when naturally exposed to a particular pollutant.
The exposure time for human experiments is usually limited because of possible damage to health. Epidemiological studies can help to evaluate chronic, long-term effects.
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Sulfur dioxide effects
Sulfur dioxide is toxic, even at low concentrations. At between 0.15 to 0.25ppm (parts per million) and an exposure time of from 1 to 4 days, or from an equivalent exposure to 1 to 2ppm over 3 to 4 minutes, the effect on normal people is cardiovascular distress. An hour of exposure at a level of 5ppm can produce breathing difficulties; at 10ppm lung damage and nose bleeds can occur.
Carbon monoxide effects
Carbon monoxide acts in the blood to produce carboxyhemoglobine which inhibits the blood's ability to carry oxygen. Normal levels of carboxyhemoglobine, for non smokers, are less than 0.4%. Values of between 2.5 and 3% decrease performance in angina patients. Concentrations between 4 and 5% cause headache due to oxygen deficiency while concentrations around 10% start to affect heart function; vision is impaired, along with manual skills and learning abilities. Higher concentrations can produce more serious effects and even death.
Human responses to ozone expositions
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Response |
Subject |
Exposure Conditions |
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Decrease of 5 - 10% in respiratory function |
Young healthy men |
0.18 ppm in intermittent heavy exercise during 2 hours--O3 in purified air |
|
Coughing |
Healthy children |
0.10 ppm--Program normal summer--O3 in atmospheric air |
|
Young healthy men |
0.12 ppm in intermittent heavy exercise during 2 hours-- O3 in purified air |
|
Reduced athletic performance |
Young healthy men |
0.08 ppm in moderate exercise during 6 hours --O3 in purified air |
|
Young healthy men and women |
0.12-0.13 ppm in intermittent heavy exercise during 16-28 minutes--O3 in atmospheric air |
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Young healthy men |
0.18 ppm--with respiratory flow of 54 lt/min during 30 minutes--O3 in atmospheric air |
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Young healthy men and women |
0.12-013 ppm in excersice and respiratory flow of interchange during 16-28 minutes--O3 in purified air |
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Increased nasal permeability |
Young healthy men |
0.08 ppm--in moderate exercise during 6 hours--O3 in purified air |
|
Young men having allergic rynitis |
0.18 ppm--in heavy exercise during 2 hours--O3 in purified air |
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Increased nasal permeability |
Young healthy men |
0.40 ppm in intermittent heavy exercise during 2 hours--O3 in purified air |
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Nasal inflammation |
Young heathy men |
0.08 ppm in moderate exercise during 6 hours--O3 in purified air |
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Acelerated tracheo-bronchial flow of particles |
Young heathy men |
0.20 ppm--in intermittent light exercise during 6 hours--O3 in purified air |
Nitrogen dioxide effects
Nitrogen dioxide increases the risk of respiratory disease at levels above 0.062 to 0.109 ppm over a 2 to 3 year exposure period. A concentration of 0.12 ppm is unpleasant to the sense of smell (immediate perception). A concentration of 0.25 ppm for a period of 8 months produced broken leaves in orange trees, while 0.5 ppm for 35 days causes clorosis. Effects on the pulmonary system of rabbits were detected following exposure to 0.25 ppm for 4 hours/day for 6 days.
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