90% OF AIR-BORNE MATERIAL IS NATURAL

There is a drive among environmentalists (who are now a massive number of people in local and national government) to persuade the public that all our problems are a result of mankind and if only we would stop polluting the air everything would be fine. In fact there are a vast range of natural pollutants which we can do nothing about, as this extract from Wikipedia explains 

"Human-made (anthropogenic) aerosols account for about 10 percent of the total mass of aerosols in the atmosphere as estimated in 2010. The remaining 90 percent comes from natural sources such as volcanoes, dust storms, forest and grassland fires, living vegetation and sea spray, emitting particulates such as volcanic ash, desert dust, soot and sea salt".  [Particulate matter - Wikipedia ]

They could have included pollen and spores from bacteria yeasts and mould which we know are harmful. It is this lack of balance that is misleading. Human pollution has decreased a huge amount during the past 50 years or so and yet there is more emphasis than ever on reducing our now small contribution further, which comes at an ever increasing cost.