21. Denver-Aurora, CO
A number of people with lung cancer is 1,452, while a lot more (precisely 237,472) suffer from adult asthma. Denver-Aurora is ranked 30th for 24-hour particle pollution out of 186 metropolitan areas and 131st for annual particle pollution out of 184 metropolitan areas.
![25 Most Polluted Cities in the US in 2017](https://imonkey-blog.imgix.net/blog/wp-content/uploads/2017/03/22144714/pollution-2049211_1920-750x421.jpg?auto=fortmat&fit=clip&expires=1752624000&width=480&height=269)
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