The famed redwoods of Sequoia National Park are slowly yet surely being replaced by another kind of enduring landmark: a sky-spanning carpet of lung-blistering smog.
via Sequoia National Park Is Stuck in Pollution Hell – Neighborhoods – The Atlantic Cities.
Click the map to find out about current air quality levels where you live. 
Pollution Masks - The 'Original' and still the best - Established 1993 - Made in the UK 
Respro® Masks are reusable
Respro® Bulletin Board 