Western wildfires have been sending clouds of acrid smoke into national parks, obscuring views and raising health concerns, especially for the young and the elderly. Things got so bad at Muir Woods National Monument on Sunday that the park was closed.
Poor air quality in Bay Area parklands may pose risk to everyone on some level. Some individuals may experience more serious health effects. Visitors should avoid unnecessary outdoor activities. Muir Woods, Alcatraz and Fort Point CLOSED.
A quick check of websites of some national parks in the West didn't note any similar warnings, though photos from park webcams probably got the message across.
Crater Lake National Park, Oregon

This view of Crater Lake from Sunday afternoon is not a chamber of commerce pleaser/NPS webcam
Mount Rainier National Park, Washington

Smoke obscured Mount Rainier on Saturday/Rebecca Latson
"It’s a dirty yellow smoke with the distinct smell of campfire," said Traveler Contributing Photographer Rebecca Latson, who visited Mount Rainier this past weekend.
Sequoia National Park, California

The view from the Giant Forest webcam on Sunday was hazy/NPS webcam
Yosemite National Park, California

The view west from the Yosemite Valley on Sunday afternoon/NPS webcam

The view towards Half Dome wasn't much better/Yosemite Conservancy webcam
Not everything was smoky and discouraging, though, as this shot from near the roof of Rocky Mountain National Park in Colorado proved:

A nice clear view from Alpine Visitor Center in Rocky Mountain National Park on Sunday/NPS
Comments
We were in Yellowstone last Friday and yesterday. Smoke is medium dense most areas, but pretty thick in Lamar Valley.
Living at the gates of North Cascades NP, it is noticeable but not oppressive. Noticeable enough to make any activity require a conscious choice. For example, I made the decision to not make the 30+ minute drive to a physical therapy appointment, based on air quality.
Overall, though, it is not as significant as the grey wall of smog noticed 30-some years ago driving south from SF towards LA, before they put in the environmental controls the anti-environmentalists hate.