I don’t think it’s just particulates, Denver and the front range are routinely in the news for ozone issues [0]. I think that might be altitude related as well,

I don’t think it’s just particulates, Denver and the front range are routinely in the news for ozone issues [0]. I think that might be altitude related as well, though it may just be pollution. Den doesn’t quite make the top ten list of US cities with ozone problems, but it’s gotta be close [1]. [0] https://www.govinfo.gov/app/details/FR-2019-08-15/2019-17405 https://www.govinfo.gov/app/details/FR-2019-08-15/2019-17405 [1] https://www.usnews.com/news/cities/slideshows/the-10-us-cities-with-the-most-ozone-pollution?slide=12 https://www.usnews.com/news/cities/slideshows/the-10-us-citi...