The main exhaust gas pollutants and their effects are described in more detail below:
CO
Carbon Monoxide reduces the blood's Oxygen carrying capacity which can reduce availability of Oxygen to key organs. Extreme levels of exposure, such as might occur due to blocked flues in domestic boilers, can be fatal. At lower concentrations CO may pose a health risk, particularly to those suffering from heart disease.
NOx
Oxides of Nitrogen react in the atmosphere to form Nitrogen Dioxide (NO2) which can have adverse effects on health, particularly among people with respiratory illness. High levels of exposure have been linked with increased hospital admissions due to respiratory problems, while long term exposure may affect lung function and increase the response to allergens in sensitive people. NOx also contributes to smog formation, acid rain, can damage vegetation, contributes to ground level Ozone formation and can react in the atmosphere to form fine particles ('secondary particles').
Particles
Fine particles can have an adverse effect on human health, particularly among those with existing respiratory disorders. Particles have been associated with increased hospital admissions due to respiratory and cardiovascular problems, bringing forward the deaths of those suffering from respiratory illnesses and a reduction in life expectancy.
HC
Hydrocarbons, contribute to ground level Ozone formation leading to risk of damage to the human respiratory system. In addition, some kinds of HCs are carcinogenic and they are also indirect greenhouse gases.
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