Effects are generally irritation and reduced lung function with increased incidence of respiratory disease, especially in more susceptible members of the population such as young children, the elderly and asthmatics.

Standards and guidelines for air quality remain benchmarks against which the quality of air is assessed. Few studies have been carried out on populations from different ethnic backgrounds, with varying nutritional status. Living conditions, stress or history of chronic disease, all of which could alter the relationship for exposure to air pollution.

International approaches to air quality management have become increasingly important. Reducing emissions has been shown to lessen costs associated with medical consultation and offset a moderate fraction of expenditure associated with air quality improvement.

Types of Urban Air Pollution

Sulphur Oxides
Sulphur dioxide is often a local pollutant but can also be subject to long-range transport processes. In oxidized forms it can persist and be transported considerable distances as a fine particulate and can be an important component of haze. Sulphur dioxide is very soluble in water and therefore can cause irritation to the moist surfaces of the nose, mouth, pharynx and major bronchi.

Nitrogen Oxides
The major health impacts of nitrogen dioxide are increased incidence of lower respiratory tract infection in children and decreased airway responsiveness in asthmatics. Children, the elderly, asthmatics and individuals with chronic obstructive pulmonary disease are more responsive to nitrogen dioxide than others in the community.

Particulates
Fine particulates can be produced in air as a result of slow atmospheric reactions among gases including the oxidation of Sulphur dioxide and nitrogen dioxide and nitrogen dioxide emitted at distant locations, and transported by atmospheric processes.