The wildfires in Northern California have grown so intense that the smoke can be seen hundreds of miles away from outer space.
As a result, many people, even those dozens of miles away from flames, are at risk for asthma attacks, respiratory distress, and cardiac events due to the increased air pollution.
In San Francisco, the smoke and haze led some residents to wear masks to protect themselves from the smoke.
Dr. Robert Blount, assistant professor of pulmonary pediatric and adult medicine at the University of California San Francisco, said during last year's California fires that if people can smell or see smoke they should take steps to protect themselves.
“If there's enough smoke that you can see it or smell it… then it's a dangerous level,” he told Healthline.