Ground level ozone rises each spring across the whole northern hemisphere as increasingly strong sun acts upon air pollution that built up over winter. First indications of this were measured across Scotland and Yorkshire last month. Although spring concentrations rarely reach the peaks that we experience during summertime smog, a health impacts study across Sussex found that the frequency of days with moderate ozone results in more air pollution-induced hospital admissions during spring than at any other season.
Easterly winds bought particle pollution across the eastern half of England in mid-February. The greatest concentrations were in Norwich, and the pollution extended as far west as Birmingham. Last spring particle pollution made the headlines; Paris imposed emergency traffic bans and most of the UK experienced the worst air pollution for several years. This was caused by pollution from industry and traffic mixing with ammonia from farming.
Particle pollution control focuses on industry and traffic; less attention is paid to agriculture. Farm animals dominate ammonia emissions. In the UK, half of this comes from cattle manure and slurry and a quarter from poultry. Europe-wide pigs play an important role and many emission areas are close to the UK – in the Netherlands, Denmark and Brittany. In many areas slurry spreading is restricted during autumn and winter to prevent river and water pollution but this can focus slurry spreading during the spring when fertilizer is also being applied to crops. The effect of this burst of agricultural ammonia on our springtime air pollution is largely unstudied.