Telegraph: Here we go again. No sooner has the spring sun finally come out than pollution goes sky high, as sunlight reacts with contaminants that have built up in the air, creating smog. It is becoming as symbolic of the season as daffodils, T-shirts, and the first cuckoo. Thursday suffered the worst air quality with high levels across central and eastern England since a mixture of smog and red dust, blown from the Sahara, raised outrage almost exactly a year ago. Again, asthma sufferers were warned to...