• New York; Washington, D.C.; Montreal; and Toronto have some of the worst air quality in the world, according to an AQI tracking service.
• Canadian wildfires have sent smoky air around much of North America over the last few weeks.
• The effect of the wildfires has been significantly worsened by climate change, researchers have found.

Four of the five cities with the worst air quality in the world are in North America, including New York, a grim distinction fueled by devastating forest fires across Canada that have sent smoky air across the continent, according to data tracked by IQAir.

New York City now has the second-worst air quality in the world with a recorded air quality index of 162, lagging only Jakarta.

Toronto and Montreal rank as No.3 and No. 4, reporting an AQI of 155 and 153, respectively.

Anything above an AQI of 150 is considered "unhealthy" air.

The fifth-ranked city, Washington, D.C., is hundreds of miles away from where Canadian wildfires continue to rage. There, air quality is slightly better than the other three North American cities on the list, with an AQI of 122. That number is considered "unhealthy for sensitive groups."

The Canadian wildfires have burned for weeks, with record heat and drought prompted by climate change creating ripe conditions for longer-lasting, more intense wildfire activity, research has shown.

New York Gov. Kathy Hochul warned citizens that potentially dangerous air quality reflected a grim distinction for state residents. "This is not something that we're talking about future generations dealing with," Hochul said in a press conference earlier this week. "We are truly the first generation to feel the real effects of climate change."

— CNBC's Cat Clifford contributed to this report.