The air quality in Metro Vancouver was worse than in some of the world's most polluted cities on Monday and Tuesday as smoke from wildfires burning across the Pacific Northwest continues to blow into the region.

Health officials extended an air quality advisory Tuesday, a day after it was first issued over concerns about elevated levels of fine particulate matter, or PM2.5.

"You can definitely feel it in your nose and in your lungs," said Nathan Joe, a construction worker in North Vancouver who has no choice but to spend his time outdoors, despite the advice of the region's medical officers.

PM2.5 refers to solid or liquid particles in the air that are 2.5 micrometres or less in diameter. These particles easily make their way indoors due to their small size.

"We are still seeing high levels of fine particulate matter and that's coming into the region from the smoke from the wildfires in B.C.," said Julie Saxton, an air quality planner with Metro Vancouver.

A healthy level of fine particular matter is 25 or below, but readings in North Vancouver came in at 56.3 Tuesday. That's more than Los Angeles and even Beijing, which are both considered among the most polluted cities in their respective countries.

The low air quality is most likely to have adverse health effects on the elderly, the young and those with chronic heart and lung conditions.

But at those levels, health officials are urging everyone to be cautious outdoors.

"The truth is we're all inhaling these things and so we all have to sort of monitor how we're feeling and know ourselves and work with our doctors to figure out what's best for us when the air quality gets like this," said Dr. Mark Lysyshyn of Vancouver Coastal Health.

Lysyshyn said VCH doesn't actively monitor the number of hospital or doctor visits associated with air quality advisories, but said "we know that when air quality reaches this type of level, that people do have exacerbations of respiratory problems, of heart problems and of other illnesses."

According to Saxton, PM2.5 concentrations are highest near the mountains, but conditions are dangerous across the board.

And it's unclear when the smoke might leave the region.

Saxton said it would require a combination of changing wind patterns, rain and wildfire activity for skies to clear.

In the meantime, residents can check the specific air quality rating for their area by visiting AirMap.ca.

For the latest forecast and weather warnings, check out CTV Vancouver's new (and free) weather app! Click here to find out more information including how to download it to your smartphone or tablet.

With files from CTV Vancouver's Sheila Scott