City Hall has issued a high air pollution alert for London, Barnet included, for Tuesday 10 November. Fog, fireworks and wood smoke let particles build up.

Air pollution in Barnet, as across London, is forecast to reach “high” levels on Tuesday 10 November. The Mayor of London, Sadiq Khan, issued the alert on Monday and is asking people who are most vulnerable to look after themselves, and everyone else to burn and drive less. It is the fourth high air pollution alert in the capital this year.

The alert covers the whole of London, so it applies from Edgware and Mill Hill to Golders Green, Finchley and High Barnet. You will see it on the countdown signs at every bus stop in the borough, and on the Underground, where City Hall displays its high alerts.

Why the air is bad this week

The problem is particle pollution. City Hall said dense fog and very light winds allowed pollution to build up over the weekend and to linger into Monday morning.

It said smoke from Bonfire Night and Diwali fireworks, and from wood burning, “is likely to have contributed”.

Forecasters at Imperial College London advised the Mayor to issue the alert. The Mayor set up the warning system in 2016; Imperial produces the forecasts, and City Hall says they are checked against other public forecasts, from airTEXT, the Met Office and London Air, before an alert goes out.

City Hall’s notes also point out that particles drift across borders: concentrations “are heavily influenced by meteorology, background concentrations and sources outside of London, including on the continent, on top of local emissions.”

Who should take care

The moderate and high thresholds are set by Defra’s national Daily Air Quality Index. City Hall said both are “substantially above” the World Health Organization’s guideline values and mark the levels at which short-term health effects may occur, “particularly for people with pre-existing conditions such as asthma or chronic obstructive pulmonary disease (COPD).”

GPs and hospital emergency departments across London, including those serving Barnet, have been sent extra details so they can advise vulnerable patients. The alerts have gone to NHS GPs and emergency department consultants since 2024. Schools and the London boroughs are alerted too.

What you can do on Tuesday

City Hall’s list for all Londoners:

  • walk, cycle and use public transport more often, and avoid the busiest roads when you can
  • drive less, and when you do drive, “drive smarter”: car share if you can, turn the engine off when you are not moving, and keep the vehicle well maintained
  • compost garden waste or take it to a refuse centre rather than burning it
  • avoid unnecessary burning at home, “for example, using a wood burner or open fire”

For anyone walking to school or work in Barnet, the busiest-road advice means roads such as the North Circular, the A1 and the A41.

What City Hall said

Mete Coban, the Deputy Mayor for Environment and Energy, said: “Toxic air is responsible for thousands of premature deaths in London each year, which is why the Mayor has done everything in his power to tackle it, which includes launching the world’s largest clean air zone.

“It is really important we all do our bit to protect those who are most vulnerable as we continue working to build a safer and greener London for all.”

City Hall explains how London’s air is monitored, and links to a dashboard of local readings, on its air quality monitoring page.