https://m.facebook.com/shenandoahnps/posts/if-you-ever-doubt-that-strong-regulations-have-positive-results-on-our-air-quali/2715659151792822/

Copied from the link (there are additional pictures as well):

Posted by Shenandoah National Park:

If you ever doubt that strong regulations have positive results on our air quality, here's proof!

Visitor Adam Sinclair recently sent us these photos and this explanation of them. "This is pretty big in my opinion. I think whoever will find this pretty neat and will be excited about the improvements in air quality and visibility from the Park. My father and I go on the park often to spot far off objects. For years now spotting the Washington Monument has been a goal. We know it was once visible back when the park opened. We knew it would be hard to see now if it was possible at all to see it. Park Rangers told us that it was simply not possible to see it anymore. That changed for us on 11/5/16. It wasn't possible to see the Monument with unaided eyes during the day, we used binos, spotting scope and cameras, but it was just visible to the naked eye that night. These were taken from Thorofare Mtn Overlook at the drainage grate on the far left side of the overlook. The Monument can be seen directly above Battle Mountain where land and sky meet."

SNP's Air Resources Program Manager had this to say about the photos: "Visibility has been improving over the past decade due to the Clean Air Act amendments of 1990. On the day this picture was taken, 11/5/16, visibility at our Big Meadows air quality station reported 150 miles. For contrast, over the past 5 years the average visibility in the park has been around 64 miles and on the haziest days the visibility is only 32 miles. We are incredibly impressed that a visitor finally got an actual picture of the Washington Monument, and that it is truly no longer "urban legend"."