Why is ozone lower in the middle of London?
News from the LAQN

Each month, scientists at King’s answer dozens of email and telephone enquiries from members of the public, air quality professionals and students. Questions are diverse, encompassing air pollution health effects, access to the free LondonAir data feeds and smoke from wood burners. The most popular question at the moment, stemming from our Nowcast pollution maps, is "why is ozone lower in the middle of London?"

More and more Londoner’s are using the Nowcast to get access to hourly pollution maps for London and they are noticing greater ozone concentrations in the suburbs than in the centre. Although ozone in the upper atmosphere decreases our UV exposure, ozone is an incredibly reactive gas. At ground level, it is formed from chemical reactions between natural, traffic and industrial pollution in strong sunlight, so that concentrations are normally greatest during summer afternoons. Some people doing sport can notice breathing problems at these times even if they are not asthmatic. Although traffic pollution contributes to ozone formation, fresh vehicle exhaust reacts to consume ozone locally. This means that ozone is sometimes lower in city centres and close to busy roads.

Each hour King’s calculates pollution concentrations at 5,563,706 points within the M25 to create our pollution maps. You can see these updated each hour maps on LondonAir or through the CityAir App.

Item date 15/07/2015

Follow Us
Our newsletter
Privacy Notice Summary:
  • Who this is for: You must be at least 13 years old to use this service.
  • What we collect: We store your email address
  • Who we share it with: We use "Campaign Monitor" to store it, and do not share it with anyone else.
  • More Info: You can see our full privacy notice here

AirMail newsletter

The latest news and research from ERG: View the archive