VICTORIA -- Greater Victoria residents woke up under smoky skies for the second time this week on Friday as wildfires in B.C. and the western United States raised air quality health alerts for the capital region.

The federal government's Air Quality Health Index, which rates air quality on a scale of one (low risk) to 10 (very high risk), rated the region's air quality at 10-plus by 7 a.m.

The province warned that elevated levels of sulphur dioxide have been detected, which can be particularly harmful for people with chronic respiratory conditions like asthma.

The province and Environment Canada say under such conditions, residents should avoid strenuous outdoor activities, particularly for children and seniors.

The smoky haze and campfire smell is due to overnight weather conditions that carried smoke into the region from wildfires in the B.C. Inetrior, Washington state and Oregon.

"With falling temperatures overnight, temperature inversions in mountain valleys can increase the likelihood of smoke being trapped near the ground," according to a statement from Environment Canada.

Environment Canada is maintaining smoky skies bulletins for most of Vancouver Island and all of the inner south coast and southern B.C., east to the Kootenay region.

The advisory says forecast models over the next 24 to 48 hours show the potential for long-range transport of smoke from dozens of wildfires in the northwestern United States.