Health officials in Metro Vancouver and the Fraser Valley have issued yet another air quality advisory as smoke from wildfires burning throughout the Pacific Northwest moves into the region.

On Saturday, gusts of clean marine air blew last week's smoke away from the South Coast, but a change in weather patterns the next day once again led to elevated levels of fine particulate matter, or PM2.5, in the region.

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.

"Persons with chronic underlying medical conditions should postpone strenuous exercise until the advisory is lifted," regional authorities warned Monday. "Exposure is particularly a concern for infants, the elderly and those who have diabetes, and lung or heart disease."

Anyone who experiences symptoms such as chest discomfort, shortness of breath, coughing or wheezing should see a doctor.

And with temperatures expected to reach the high 20s along the coast and as high as 30 C further inland, health officials say it's also important to stay cool and hydrated.

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.