The air pollution anomaly John Cannell, Vitamin D Council 21 October 2014 The air pollution anomaly As the author points out, a number of studies have shown a positive association between autism and air pollution. If air pollution were the temporal driver of autism, then the autism epidemic should have occurred in the 1950's and 60's, before the Clean Air and Water Act was enforced. It is well known that air pollution lowers 25-hydroxy-vitamin D [25(OH)D] levels: http://www.ncbi.nlm.nih.gov/pubmed/22904180 http://www.ncbi.nlm.nih.gov/pubmed/24090719 http://www.ncbi.nlm.nih.gov/pubmed/23935619 http://www.ncbi.nlm.nih.gov/pubmed/20799984 Also, 25(OH)D levels are inversely associated with autism. http://www.ncbi.nlm.nih.gov/pubmed/24927807 http://www.ncbi.nlm.nih.gov/pubmed/20569030 http://www.ncbi.nlm.nih.gov/pubmed/24089013 The air pollution anomaly is explained by the fact that, in spite of cleaner air, 25(OH)D levels have been falling over time, due to sun avoidance: http://www.ncbi.nlm.nih.gov/pubmed/19307527 Also, surface UVB is inversely associated with autism prevalence: http://www.ncbi.nlm.nih.gov/pubmed/24494049 There are multiple reasons to think that low vitamin D is one of the important environmental agents in the gene/environment interaction that causes autism. http://www.ncbi.nlm.nih.gov/pubmed/22898564 http://www.ncbi.nlm.nih.gov/pubmed/24558199 http://www.ncbi.nlm.nih.gov/pubmed/22522213 http://www.ncbi.nlm.nih.gov/pubmed/24494055 Sincerely, John Cannell Competing interests I am employed by the Vitamin D Council, a non-profit, and recieve remuneration from Purity Products.