Petrol is so volatile that a parked car will give off fumes by evaporative emission

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  Accounts for 10% of VOC’s

Sulfur compounds come from impurities in fuel

Nitrogen oxides formed from air itself due to high temperature

Sulfur and nitrogen oxides can cause acid rain

Carbon monoxide from incomplete combustion is toxic to humans

Particulates are also formed from incomplete combustion, causing irritation and disease

Ozone is a secondary pollutant

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  Not released directly into atmosphere, formed from primary pollutants

UV reactions occur in photochemical smog

Ozone is toxic at ground level and acts as a greenhouse gas

Smog causes haziness and breathing difficulties and irritation