London has experienced three high ozone pollution alerts so far in 2026, including two during a June heatwave, but many residents remain unaware of what these warnings mean. The Mayor of London, Sir Sadiq Khan, has been urged to follow Paris by imposing driving restrictions during such episodes.
Green Party calls for French-style measures
Caroline Russell, leader of the Green Party on the London Assembly, said City Hall should adopt clear, firm restrictions when ozone pollution reaches dangerous levels. In Paris, authorities reduce speed limits by 20 km/h and can ban older, more polluting cars from roads when ozone thresholds are exceeded.
"We need to be a bit more French," Russell told the Local Democracy Reporting Service. "In Paris, they issue warnings for high ozone across a really wide area, the equivalent of Greater London, and reduce speed limits while advising people not to drive if possible."
Understanding ozone pollution
Ozone at ground level is a harmful gas formed when sunlight reacts with chemical emissions from vehicles and factories. Unlike particulate matter, it is invisible, making it harder for the public to grasp the danger. Russell noted that ozone pollution has a significant impact on people with lung and heart conditions, yet "not many people talk about it."
During the June heatwave, Sir Sadiq advised Londoners to avoid idling engines, burning garden waste, and to use public transport instead of private cars. However, Russell argued that the current alert system—using terms like "moderate" and "high"—is insufficient. She proposed adopting "amber" and "red" warnings similar to heat alerts, which would be more intuitive.
Mayor's response
At Mayor's Question Time earlier in July, Sir Sadiq acknowledged that hotter, sunnier summers are increasing conditions for ozone formation. He said he would consider whether the current alert system is "user-friendly" and explore a traffic light system with officials. Regarding the Parisian approach, he stated, "I'm always happy to learn from other cities if they're doing things in a more effective way."
Russell emphasized that clear communication and action are essential: "The Mayor could both implement this system and also think about reducing speed limits when the risk of ozone pollution is high, and advise people not to drive to reduce the likelihood of some Londoners having heart attacks or extreme asthma attacks."
Broader health and climate context
Ozone pollution is an added health stressor during heatwaves. Russell called for London to learn from global best practices: "For a big capital city like London with a complex transport network, it's worth learning from other places and looking out at good practice from all around the world where they've thought about protecting people from extreme heat."
She concluded: "We need to do everything possible to make sure people can trust the air they breathe."
