there is an intense area of high pressure over western europe at the moment which means that car pollutants and other emissions are not being blown away as usual, and as a result londoners are being advised not to undertake strenuous physical activity today. the government s daily air quality index says even healthy people should avoid physical exertion, but extra caution is being offered to those who are elderly and those with lung and heart problems, and those with asthma may need to use their inhaler more often. the government s forecast predicts pollution levels will hit band ten, which is the highest on the scale, and the last time we saw this was in march 2018. pollution levels will be high across the whole of the city today, but the stretch from stratford in the east to hammersmith in the west will be particularly dirty. it is now six weeks since storm arwen left a trail