Key messages

• There is no evidence that air pollution causes asthma, but it can trigger attacks in people who have asthma.
• Significant outdoor air pollutants for people with asthma are: airborne particles, sulphur dioxide, nitrogen dioxide and ozone.
• People with asthma in urban areas can be advised to remain indoors on smoggy days and, if outdoors, to avoid heavy exertion.
• Significant indoor air pollutants for people with asthma are: environmental tobacco smoke, formaldehyde, nitrogen dioxide and volatile organic compounds.
• Smoking by either parent – particularly by the mother – increases the risk of asthma in children. Doctor-diagnosed asthma is more common among non-smoking adults exposed to environmental tobacco smoke than those who are not exposed.
• People with asthma should avoid smoking and exposure to environmental tobacco smoke indoors and in confined spaces such as cars.

Introduction

Air pollution is often mistakenly thought to be a major environmental problem and a possible explanation for the high prevalence of asthma in Australia. While there is no evidence that air pollution causes asthma, it can trigger attacks in people who have asthma. Many studies have found a link between some air pollutants and the worsening of asthma symptoms.

The impacts of air pollution are especially severe when high levels of outdoor pollution are combined with high levels of indoor pollution.

Important outdoor air pollutants are: particles, sulphur dioxide, nitrogen oxides, ozone, carbon monoxide and lead.

Indoor air pollution arises from both outdoor pollution and indoor sources. Indoor air pollutants are either biological or chemical. Fungi, bacteria and allergens from house dust mites, cats and cockroaches are important indoor biological pollutants^a. Significant indoor chemical pollutants are: environmental tobacco smoke, formaldehyde, nitrogen dioxide and volatile organic compounds.

a. Information on indoor biological pollutants and their health effects can be obtained from the brochure, Asthma and allergy: a guide for health professionals, Australian Government Department of Health and Ageing, 2003.