Air pollution alert issued
The Mayor of London, Sadiq Khan has triggered a ‘high’ air pollution alert for tomorrow, Tuesday 13 June, as London experiences the effects of pollution which has travelled in from the continent alongside a build-up of local emissions and sunny weather with high temperatures.
Imperial College London forecasters advised the Mayor to issue the alert due to a strong likelihood of high ozone levels, caused by the hot, sunny weather tomorrow and south-easterly winds blowing existing pollutants from the continent towards London.
This is the second high air pollution alert this year. The last alert was in January, with one day of high pollution followed by three days of moderate air pollution.
Tomorrow will be the 201st day of either moderate or high levels of air pollution Londoners have experienced over the last five years. In total there have been 15 high pollution days (including tomorrow) and 186 moderate pollution days since the start of 2018.
City Hall issues alerts to Londoners, schools and local boroughs when moderate, high, or very high air pollution is forecast. High air pollution alerts are also displayed at public locations across London, including all bus stop countdown signs, as well as on the Underground and on roadside signs.
The Mayor of London, Sadiq Khan, said: ”We all know the dangers toxic air poses to Londoners, which is why I am doing everything in my power to tackle it. On Tuesday alongside the current high temperatures, we will also experience high levels of air pollution.
“Pollution and heat can be a dangerous combination, which is why I’m urging Londoners to look after themselves and each other by choosing to walk, cycle or take public transport, avoid unnecessary car journeys, stop their engines idling and refrain from burning wood or garden waste, all of which contribute to high levels of pollution. This is particularly important in order to protect those who are most vulnerable and help us to build a safer and greener London for all.”
Notes to editors
Ozone is a secondary pollutant, meaning it is created in the atmosphere through a cycle of reactions of its precursors nitrogen oxides and volatile organic compounds (VOC), sunlight is also a key part of the ozone production cycle. In the summer stagnant air leads to the build-up of these precursor compounds, while more sunlight and higher temperatures increase the rates of reactions that generate ozone.
The moderate and high daily thresholds are based on Defra’s national Daily Air Quality Index (DAQI). These thresholds are nearly two and a half times higher than the World Health Organization (WHO) recommended limits for exposure and represent especially acute exceedances which can have immediate health impacts for individuals with pre-existing conditions such as asthma or Chronic obstructive pulmonary disease (COPD) .
In 2016, the Mayor set up a system to warn Londoners about moderate and high pollution episodes. These forecasts are created by Imperial College London, and checked against other public forecasts (airTEXT, Met Office) to predict when air pollution in the capital will reach moderate, high or very high.
More information about the alerts can be found here: https://www.london.gov.uk/programmes-and-strategies/environment-and-climate-change/pollution-and-air-quality/monitoring-and-predicting-air-pollution