Thick haze is blanketing Western Washington right now, due to wildfire smoke from fires in Canada and across the Pacific Northwest. Air quality is expected to improve as the week goes.

Puget Sound Clean Air Agency says these are the highest particulate levels so far this summer. The air quality in Western Washington reached "unhealthy for everyone" to “very unhealthy for everyone” Wednesday morning at most monitoring sites.

“Last summer we saw levels about this high and before that, in terms of summertime impacts, we haven't really seen this in over a couple decades,” said Erik Saganic, air resources specialist for Puget Sound Clean Air Agency.

Also see | Keep windows closed at night while air quality is in 'unhealthy' range

Saganic says people with breathing problems or compromised health should stay inside. Close the windows and doors. He says just doing that can cut fine particulate levels in half.

“We know that these fine particles can actually cause heart attacks and strokes,” Saganic said.

Although air quality is expected to improve later Wednesday, fires are still burning, and a another shift in the wind could bring smoke back to western Washington early next week.

RELATED: Seattle tourists greeted with hazy hello

Scroll below for instructions on a DIY air filter

Visitors to West Seattle looking across Elliott Bay saw downtown melting into a gray haze. Up 73 floors inside the Columbia Center Skyview Observatory, it was like staring into a cloud.

“When I woke up this morning and could barely see the city, I was really surprised,” said Justina Mobley, who tried to take a photo of the skyline from West Seattle.

“You can tell it's smoke and you can smell it in the air,” Mobley said.

On Facebook, viewers shared what they are doing to adapt:

“Keeping the kids and pets inside,” said Courtney C.

“Keeping my inhaler in hand,” said Melody S.M.

“I'm in downtown Seattle right now, and on every street corner people are coughing,” said Annette R.

If you don't have an air filter, you can make one. Buy what's called a MERV 13 furnace filter, and tape it to the back of a box fan. Puget Sound Clean Air says that can provide a 90% improvement in fine particle levels.