Alberta has endured some of the worst air quality in the world this week due to wildfire smoke

As wildfire smoke swirled, parts of Alberta have endured some of the worst air quality on the planet this week, in particular when it comes to fine particulate matter.

That's according to data tracked by the World Air Quality Index, a non-profit project that collects information from air monitoring stations around the globe.

"That very poor air quality now puts Alberta on the world map," meteorologist Jaclyn Whittal reported for The Weather Network, based on data from the index.

On Tuesday, Calgary's air quality hit a level of 539 on the index, which is well beyond the "very unhealthy" threshold and into the "hazardous" range.

"What does this mean? Well it means it's absolutely atrocious in terms of breathing conditions," Whittal said.

Readings from across the province meant Alberta had the "worst air quality in the entire world" on Tuesday, she added.

Since then, even higher readings have been recorded in Alberta, including an index level of 626 in Grande Prairie on Thursday at noon.

The index combines several kinds of air pollutants into a single measure, but the most prevalent in Alberta due to the wildfires is fine particulate matter.

Abbreviated as PM2.5, these are extremely tiny particles in the air — less than 2.5 microns in diameter. (A micron is one 1,000th of a millimetre.)

"Human hair is about 60 to 70 microns in diameter so a PM2.5 particle is roughly 30 times smaller than the diameter of a human hair," said Mandeep Dhaliwal, air quality program manager with the Calgary Regional Airshed Zone Society.

"So not only can you not see it, your body does not feel it either when you inhale it."

The Calgary Regional Airshed Zone Society monitors various pollutants at stations dispersed across the city.

Earlier this week, as wildfire smoke swept into Calgary, the PM2.5 readings at a southeast monitoring station surged into hazardous territory.

At 11 a.m on Tuesday, the level of fine particulate matter reached a level of 558 micrograms per cubic metre of air.

That's seven times higher than Alberta's recommended maximum hourly exposure.

Level of fine particulate matter (PM2.5) in Calgary air

The average level of PM2.5 in the air of New Delhi, India — which has some of the worst air pollution in the world — was 99 micrograms per cubic metre in 2019, according to the Swiss firm IQAir, which tracks air quality globally.

Of course, there is a difference between persistent air pollution, which is harder to avoid, and shorter-term spikes in pollution like Alberta is experiencing now.

Health Canada advises minimizing exposure to fine particulate matter as much as possible, "as there is no apparent threshold for the health effects of PM2.5."

"It's not good for you, that's for sure," said Dr. Raj Bhardwaj, an urgent care physician in Calgary.

"If you've got the option to avoid it, then, yeah, I would avoid it."

Bhardwaj said fine particulates have "mostly short-term but also long-term effects" on the human body.

"They get really deep into your lungs because they are such small particles; that causes more inflammation, more irritation," he said.

"With respect to longer term issues, it actually increases our risk of cancer, and there's new research saying that it probably also increases our risk of neurological problems — so problems with memory, attention, behaviour and things like that."

Bhardwaj said you can reduce your exposure by staying indoors when PM2.5 levels are high and wearing an N95-grade mask when outdoors.