Upstate New Yorkers who went out and about Tuesday, or just took a peek outside their window, couldn't miss it: Ominous Canadian wildfire smoke that cast a grey gloom on most of the state.

As the sun started to set, observers really caught a glimpse at just how thick the smoke is. And with the smoky haze comes some potential health issues.

“For individuals that are sensitive to air pollution, we would recommend them staying indoors,” said Dr. Daniel Croft, assistant professor of pulmonary and critical care medicine at the University of Rochester.

That was the warning from health experts as the Air Quality Index, or AQI, monitored by the U.S. Environmental Protection Agency (EPA), spiked.

“What it’s telling us is that we’re around 100, and that’s pretty high," Croft said. "We want to be around 50 for that.”

AQI is essentially the amount of particles in the air.

“Number one, asthma. If you have asthma, these particles and this wood smoke will irritate your breathing,” Croft said.

Especially our younger and older populations — people living with COPD, or cardiovascular disease, are also at risk of adverse impacts to their health. But experts say it’s important not to panic.

“We’re going through a temporary period where the air quality is worse than usual,” Croft noted.

Croft said if you do need to be outside and have asthma or cardiovascular disease, not to over-exert yourself and consider dusting off a mask used during the pandemic.