Types of Air Pollutants (and their sources and health effects)
The various types of Air Pollutants are briefly discussed below:
Carbon Monoxide (CO):
Major Source: All gasoline vehicles more from those without a catalyst converter.
Health Effect: Highest affinity exhibited by hemoglobin, reduces the oxygen carrying ability of blood and hence increases risk for people with heart disease. Affects reflexes and thinks. Serious combined effect with other pollutants.
In mega-cities, automobiles are the commonest source of carbon monoxide (CO). Emission of CO is highest in large urban cities such as Delhi, Kolkata and Mumbai.
Carbon monoxide comprises as much as 80% from Automobiles being added in the atmosphere. CO levels are most urban areas ranges from 5 to 50 ppm.
Sulphur dioxide (SO2):
Major Source: Both petrol and diesel – basically from the sulphur level in fuel.
Health Effect: Directly affects the respiratory system. Very high irritant. When combined with particulate matter, affects people with chronic bronchial and heart patients.
Major Source: Mostly from fuel directly. Occasional formation in combustion or conversion of aromatics.
Health Effect: Known carcinogen. Direct health effect on continued exposure. Reproductive problems and birth defects are likely.
Hydrocarbons (HC) – Unburnt or partially burnt
Major Source: Major contributors are petrol vehicles without catalytic converter, two stoke engines and fuel pump stations (Spillage).
Health Effect: High irritant to eyes. Affects respiratory system. Suspected carcinogenic effect depending on presence of benzene in fuel, converted aromatics and pyro-synthesis to PAH during combustion.
Nitrogen Oxides (NOx):
Major Source: More from diesel vehicles and less from petrol vehicles.
Health Effect: Affects respiratory system due top acidic effect. Aggravates asthma and irritant to eyes. When combined with HC and other pollutants can be more harmful.
Particulate matter (PM):
Major Source: Mostly from diesel fuelled vehicles and oil burning in two stroke engines. Very fine and low in petrol fuelled vehicles.
Health Effect: Affects respiratory system more seriously. When combined with SO2, irritates and impairs breathing. Diesel exhaust particulate contains PAH which are likely to be carcinogenic to human beings.
Major Source: Petrol vehicles – Basically from lead in fuel.
Health Effect: Affects circulatory, reproductive and nervous system-mental functioning of children and increases risk to people with high blood pressure. Affects respiratory system.
Major Source: Mostly from HC and NOx.
Health Effect: Irritation to respiratory organs and eyes. Decreases the resistance power to infections. Aggravates illness.