The heavy smoke affecting the ACT is expected to continue while fires continue to burn across the border. During this time, the ACT Health Directorate’s advice remains the same.

**Information last updated on 11 January 2020**

Bushfires are part of life in Australia. These fires can produce vast amounts of smoke, off-gases and ash and there is a need to consider the most appropriate ways of providing respiratory protection for those exposed to these contaminants.

Fire decomposes or breaks down materials. The composition of these breakdown products will vary depending on:

• The composition of the burning materials - this can be from many sources
• The ventilation conditions - poor ventilation reduces the available oxygen and changes the makeup of the decomposition products.
• The temperature of the fire.
• Burning produces particles as well as gases and vapours. The gases can often include irritant gases like hydrogen chloride and acrolein.

Smoke is defined in AS/NZS1715:1994 as "particles of low vapour pressure suspended in the air. Smoke is made from the solid and liquid products of combustion. Smoke particles settle slowly under gravity. Normally, the combustion process that produces smoke also produces gases".