Poor air quality and pollution

What it is

Air quality describes how polluted the air is. When it is poor, pollutants may be hazardous to people. Be Ready says air quality has improved a lot in recent decades, yet poor air quality remains one of the greatest environmental risks to public health in the UK. Short-term exposure to high pollution affects lung function, worsens asthma and raises hospital admissions for heart and lung conditions. Long-term exposure is linked to chronic heart and lung conditions, lung cancer, diabetes, reduced cognitive performance and dementia, and reduced life expectancy.

The people most at risk are those who live or work in more polluted areas, people with heart or lung conditions such as asthma, pregnant people, babies and children, and older adults.

What it does to a home

Pollution comes indoors with the air. The one specific instruction in the Be Ready material is for wildfire smoke: if it is affecting air quality in your area, keep windows and doors closed. Otherwise the advice is about activity. At moderate levels most people continue as normal, while anyone with symptoms cuts exposure and anyone with a lung or heart condition adapts physically demanding activity outdoors. At high and very high levels everyone should try to reduce exposure, and older people and those with conditions should adapt strenuous activity and follow their management plan.

Who warns you

The government forecasts air pollution up to five days ahead from readings across the UK. The Daily Air Quality Index runs from 1, low, to 10, very high, and each band carries recommended actions and health advice. Defra's Check Air Quality service gives the forecast and updates for your area, and the Met Office publishes a guide to using the index. A free telephone update line is listed on the Be Ready page.

How the government assesses it

The National Risk Register 2025 says air pollution remains the largest environmental risk to UK public health. Short-term surges happen mainly when weather stops pollution dispersing, in low winds or a temperature inversion, and sunshine makes ozone. The reasonable worst case is a 30-day episode of elevated ground-level ozone or fine particulate matter, with more deaths from respiratory and cardiovascular conditions and pressure on hospitals; a 22-day episode is the more likely variation. Ozone episodes are commonest in summer under high pressure, particulate episodes in spring nationally but at any time in cities. Episodes can be worsened by polluted air drawn from continental Europe, dust from drought-dried soil or the Sahara, and smoke from wildfires. The register expects poor air quality to accompany a heatwave.

Where to look

• Check Air Quality at uk-air.defra.gov.uk/forecasting.
• The Daily Air Quality Index and its health advice on gov.uk.
• Related pages: hot weather and heatwaves, wildfires, droughts, hazardous substances and radiation.