People are being urged to stay indoors, and if they have to go outside, many are wearing masks.
The smoke is also a threat to many animals. Some in the wild are confused, fearing that their habitat is in danger, causing them to end up in unexpected places or even injured.
"This juvenile grey-horned owl we suspect hit a window. It could have been caused by smoke," says Stephanie Stundon, a rehabilitator at the Schuylkill Center in Philadelphia.
Animal control brought the owl in on Wednesday night. Staff are treating her for eye and beak damage.
SEE ALSO: Hazardous smoke from Canada wildfires hangs over Philadelphia, Delaware Valley
Wildlife rehabilitators have noticed a behavioral change in some animals recently because of the poor air quality.
SEE ALSO: Why smoke from wildfires could cause a host of symptoms - even in healthy people
"When they smell the smoke they are going to think fire. So they're going to go into areas you may not normally see them around, such as open parking lots. They want to try and get away from the smoke. They know they can be trapped in the trees," said Stundon.
Action News traffic anchor Matt Pellman captured a deer in our station parking lot in Wynnefield Heights.
"Kind of fear-based behaviors, like just generally trying to find safety and shelter, is really what we're going to be seeing with the wildlife in this situation," said Sydney Glisan of the Schuylkill Center.
Philadelphia Zoo closed its gates to visitors Thursday because of the poor air quality, and it's providing respite from the particulates in the air for its 1,900 animals.
"Thankfully we have a lot of holding spaces for animals. Some of the larger animals, perhaps the giraffe or rhinoceros, they don't have as much space, but we're giving them access to wherever they want to be," says Rachel Metz, the VP of animal well-being at the zoo.
SEE ALSO: How to protect your pets as smoke from Canadian wildfires fill region
How to protect your pets as smoke from Canadian wildfires fill region
Rather than corral the animals up, the zoo is offering air-conditioned spaces should the animals choose them.
"Giving them choice is the best option for them right now and it gives them the least amount of stress," said Metz.
Experts say you may notice changes in small animals that burrow underground to wait out what they suspect is fire. Some birds may be more likely to conserve energy by staying close to the nest.