Thick smoke blanketing the U.S West has become the devastating norm for millions of Americans, battling some of the world's worst air pollution.
Deadly wildfires have set ablaze nearly 5 million acres across the region, enormous plumes of ash and smoke spreading through the air, making it difficult for many locals just to breathe.
It's a major public health risk compounded by the ongoing difficulties of the coronavirus pandemic.
California resident Liliana Oseguera:
"But, you know, up here, it's completely different. We have to, you know, make sure that we keep the windows closed. And me, when I was little, I suffered with asthma so, you know, my child's, like, more prone to asthma so I have to make sure that, you know, like he's okay. But yeah, no, I've never seen anything like it."
Air pollution is linked to diseases like asthma, lung cancer, heart disease and early death.
And it's hit historically hazardous levels in cities across California and Oregon, where hospitals have reported a 10% increase in emergency room visits for breathing problems and doctors are being inundated with calls from worried patients.
Wildfire smoke mostly carries fine particulate matter from burning trees and plants, which are already harmful.
But smoke from devastated communities can also contain toxic chemicals from burned plastic and other manmade materials, polluting not only the air -- but also nearby waterways or soils.
Dr. Gopal Allada, who specializes in studying respiratory diseases, explains:
"So these are really tiny particles. And the problem with these particulate matter is that they are, well, adapt to getting into the deeper parts of the lung and cause a certain degree of inflammation, which results in symptoms such as shortness of breath, coughing, wheezing."
Allada says wildfire pollution can also make people more susceptible to COVID-19.
But he says the best masks for filtering smoke -- are the same N-95 face coverings doctors desperately need to treat COVID patients.
However, it remains difficult to help people find respite from the bad air, other than to recommend staying home and indoors.