Vehicle emissions include particulates, carbon monoxide, carbon dioxide, nitrogen dioxide, sulphur dioxide and benzene. Research suggests the most damaging of these to people's health and wellbeing are particulates and carbon monoxide. Associated mainly with diesel engines, particulates are very fine particles that settle in the bronchial pathways and lungs. They make a number of respiratory problems such as asthma and bronchitis much worse and have been associated with premature death.
Carbon monoxide is mainly associated with petrol vehicles. It is colourless, makes heart disease worse, causes drowsiness and has been linked with learning difficulties. The effects of carbon monoxide are greater in cities where there are high traffic and congestion rates.
Vehicle emissions also reduce visibility because of smog and haze, and stain buildings.