Unseasonably wet and windy weather led to low air pollution during June. Short periods of moderate air pollution were measured in London and Sheffield, and both Port Talbot and Grangemouth experienced pollution from industry. Fine weather from the 19th to 22nd caused a brief return to more typical June pollution when summer-time smog formed over the Midlands, East Anglia and southern England as far west as Bournemouth.

Low air pollution for a month is good news but pollution exposure over many years is thought to have greater health impact than short peaks. At the end of June, the EU refused to give the UK more time to meet limits for long-term public exposure to nitrogen dioxide. Originally set in 1999, these limits should have been met by 2010. Urban nitrogen dioxide is mainly from traffic. While exhaust catalysts have decreased total nitrogen oxides from petrol cars by around 96%, real-world tests show that pollution controls on diesel cars are not as effective. New diesels produce similar nitrogen oxides to those bought 15 years ago. Typical modern diesel cars emit around 20 times more nitrogen oxides than petrol cars. Less traffic would be the most effective way to decrease air pollution but is difficult to achieve quickly. Electric cars require new charging points. Offering incentives for small petrol and petrol hybrid cars, as well as reversing the trend towards more diesel vehicles, could be a practical route to controlling urban nitrogen dioxide.