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Smog and your health

Smog happens when air pollution levels are higher than usual. This can cause breathing problems for some people, so find out how you can protect your health.

Call the Defra helpline on 0800 55 66 77 for information about smog and health

Certain weather conditions can result in smog. At any time of year, but particularly in the summer and winter, still weather without much wind can lead to a build-up of harmful substances in the air (known as pollutants).

The main sources of air pollution are traffic and industrial sources, such as factories. Pollutants in the air can include tiny solid particles such as soot, as well as gases such as nitrogen dioxide and ozone. Ozone is formed when sunlight reacts with substances in the air close to the ground. These substances come from a range of sources, including petrol and other fuels.

Who is at risk from the effects of smog?

Most people won’t notice any problems when there is smog, but people who have heart conditions or lung diseases – including chronic obstructive pulmonary disease (COPD) and asthma – might notice their symptoms get worse. This is especially true for older people.

If you are affected, alter your treatment the way you normally do when your symptoms get worse. For example, if you have asthma you can use your "reliever inhaler". You should talk to your doctor if this doesn’t work.

Avoid any strenuous outdoor activity if you have noticed that your breathing is affected on hot, sunny days. This reduces your exposure to ozone.

Air pollution updates

You can find updates on air pollution at Defra’s UK air information resource pages and from Defra’s freephone helpline on 0800 55 66 77. The helpline also offers health advice.

Air pollution is described as low, moderate, high or very high. Find out more about these air pollution health bandings.

Page last reviewed: 07/05/2015

Next review due: 07/05/2017

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