Guardian: September marks the end of the UKs summer and also the end of our risk period for summertime smog. From now on, shorter days and weaker sun mean that ground level ozone wont pass six on the 10-point UK pollution index. This year summertime smog in the UK was confined to three main periods; during the early July heatwave over most of England and parts of Wales, in early August across the southern half of England spreading westwards, and then across Scotland and England later in the month. Ozone...