As dozens of wildfires continue to rage in the Western United States, smoke from the blazes has wafted over much of the country, creating hazy skies and prompting air-quality warnings as far east as D.C., New York and North Carolina.

“This is peak fire season,” said Grant Lipman, a clinical professor of emergency medicine at Stanford University and founder of the GOES Health app. The smoke from these “horrendous fires” can influence people’s health locally, regionally and nationally, he added. “It gets into the eyes, the nose, the mouth — and it affects different people in different ways.”