This spring is proving to be a repeat of last year. On 23 March, Paris banned odd number plate cars once again to bring particle pollution under control. As in 2014 this was accompanied by days of free public transport and reduced speed limits.
Once again the polluted air also covered most of the UK. Londoners experienced the top level of ten on the UK pollution scale on 17 March and levels between seven and nine were widespread; only the highlands of Scotland and north Wales escaped. Further particle pollution returned in early April. Warnings were provided for vulnerable people but no action was taken to control pollution sources.
NHS 111 and GP consultations for breathing problems increased last spring’s pollution episodes; there were around 1,600 extra GP consultations during the March episode and 2,700 in the April one.
Controlling air pollution would be helped if we knew which sources were the most harmful. To answer this question scientists traditionally compare measurements of one pollutant at a time to death and hospital statistics. But, in the real-world, we breathe a mixture of pollutants. Our spring pollution episodes have been dominated by so-called secondary particles that form when diesel exhaust, industrial pollution and agricultural emissions mix. These can drift over hundreds of kilometres. A new study from King’s College London separated days according to different pollutant mixtures and health data. Days dominated by secondary particles, such those in March and early April, were followed by 2% more deaths from breathing problems.