Canadian wildfires impacting air quality in New York City, Toronto

Smoke visible as the grey haze separate from the brighter white clouds moving through Ontario and into the United States.

While smoke from the Quebec wildfires are not expected to reach the Maritimes over the next couple days, Canadian wildfires have led to poor air quality in many major cities.

According to an air quality tracking site New York City and Toronto are the major cities with the fourth and fifth worst air quality globally as of Tuesday afternoon.

Another round of wildfire smoke is expected in Quebec, Ontario, and a large portion of the eastern United States Wednesday.

Air Quality Alerts extend across much of Quebec, Ontario, New England, and as far south as South Carolina.

Wildfire smoke is primarily composed of small particles that have a width 30 times less than that of a human hair.

Exposure to the fine particulates is not safe for anyone, but those with pre-existing respiratory issues, older adults, children, and pregnant women are particularly vulnerable. Well-fitted respiratory masks such as N95 masks are effective at filtering the particulates out.

The stalled low pressure system is playing a major role in the spread of the wildfire smoke. Wind circulation is moving smoke southward out of Quebec, into Ontario, and then southeastward in the eastern United States.

Near surface wildfire smoke will continue to be directed southward through the end of the week.A change in prevailing wind direction is expected over the weekend.

A northwest wind is forecast to develop for the Maritimes Saturday and Sunday. The more westerly component of that wind will increase the risk of wildfire smoke from Quebec reaching the Maritimes.

Air Quality in the Maritimes will need to be monitored this weekend and into early next week.