Air pollution is associated with primary health care visits for asthma in Sweden: A case-crossover design with a distributed lag non-linear model

Even though the air quality in Scania between 2005 and 2010 was within EU's guidelines, the number of PHC visits for asthma increased with increasing levels of air pollution. This suggests that as well as increasing hospital and emergency room visits, air pollution increases the burden on PHC due to milder symptoms of asthma.