| Health effects | Environmental Effects | |
| Carbon monoxide (CO) | Lethal at high doses. At low doses can impair concentration and neuro-behavioural function. Increases the likelihood of exercise-related heart pain in people with coronary heart disease | Greenhouse gas contributing to global warming |
| Nitrogen oxides (NOx) | May exacerbate asthma and possibly increase susceptibility to infections | Acid rainGround level ozone precursor |
| Hydrocarbons (HC) | Low molecular weight compounds cause eye irritation, coughing and drowsiness High molecular weight compounds can be mutagenic or carcinogenic | Ground level ozone precursor |
| Benzene (C6H6) | Classified as a human carcinogen (Group 1) by the International Agency for Research on Cancer | |
| Ground-level ozone (O3) | Irritates the eyes and air passages. Increases the sensitivity of the airways to allergic triggers in people with asthma. May increase susceptibility to infection | Oxidants to plants, impairs growth and maturation |
| Lead (Pb) | Impairs the normal intellectual development and learning ability of children | Ground water pollution and particulates in air |