September marks the end of the UKs summer and also the end of the 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 at ground level is a main pollutant in summertime smog. It is bad for our health and it is bad for plants too. Air pollution has been damaging plants for centuries; the Victorians planted London Plane trees in city centres because of their resistance to sulphur from coal burning, and images of forest dieback across northern Europe in the 1980s were a powerful illustration of the harm that industrial and traffic pollution can do to trees and, more importantly, the soils that they grow in. Ozone does not affect soils but instead it attacks plants leaves and stems causing small, pale yellow, cream or bronze pinhead sized blotches that can join together. The main crops affected in Europe are wheat, potatoes and sugar beet. Researchers from Leeds and York universities estimate that ozone reduces European wheat yield by around 3%. You can help the UK Centre for Ecology and Hydrology to track these effects by planting an ozone garden and photographing leaf damage using their app.
The Guardian, 14 September 2015 ;http://www.guardian.co.uk ;