The distinctive smell of smoke in summer is often all you need to know there is a bushfire burning.

Even if the fire is many kilometres away, the drop in air quality can be harmful for your health. Some of us – including older people and those with pre-existing health conditions – are particularly vulnerable.

There is no safe level of exposure. So here’s what to know and how to minimise your risk.

Bushfire smoke contains a mix of particles (including fine particulate matter, or PM2.5) and vapours and gases, such as carbon dioxide and nitrogen oxides.

Breathing in this toxic mixture can affect how much oxygen our lungs can absorb and how well the cells in our bodies work.

Being exposed to smoke can affect your health immediately and in the long term. The risks increase with the amount you’re exposed to – usually related to how close the fire is – and for how long.

In the short term, you might have itchy eyes, a runny nose or sore throat, and wheezing or coughing.

In healthy people, these symptoms often clear up away from smoke. But in vulnerable people, breathing in smoke can be serious and even fatal.

At-risk groups include children, the elderly, people who are pregnant, and those with diabetes or pre-existing heart and lung conditions, such as asthma.

If you experience difficulty breathing, or chest pain or tightness, you should call........

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