The government's smog warning on 21 April heralded the worst air pollution of the year so far. The UK describes air pollution as low, moderate, high or very high according to the health risk. Over the Easter weekend airborne particles reached high in Leeds, London and towns in Essex and Kent. Moderate levels were measured throughout England and Wales. Excluding Guy Fawkes, this was the worst air pollution since 2007. Strong spring sunshine and hot temperatures also caused air pollutants to react together leading to widespread moderate ozone over most of the UK and high levels in London and Manchester.
This year the fresh westerly air flow that normally brings March winds and April showers was replaced by easterly winds bringing a record breaking dry March, warm April and polluted air from Europe. No part of UK escaped moderate air pollution during May; moderate ozone reached Lerwick, Shetland, and moderate ozone and airborne particles reached Northern Ireland. Throughout Europe air pollution is caused by the combination of local traffic and industry along with pollution blown from farther afield. In the last decade airborne particle levels from Europe have decreased faster than pollution from road traffic in our cities; levels of pollution reaching the UK from Europe over Easter were around half those during the peaks in 1996, but this Easter shows the need for more control on air pollution sources at the local, national and European level.