In its “report” of the the Trump EPA’s decision not to tighten PM2.5 standards, the Washington Post ran this photo:

But…

… if you are curious enough to read the fine print caption under the photo, you find that the West Virgina coal plant featured closed in 2015 and this picture was taken on February 6, 2020.

The gray sky is not from PM2.5 — the plant has been closed for 5 years. The gray sky is fog. The plant is located in the mountainous Hansford, WV, elevation 623 feet.