While fire crews continue to battle a stubborn Richmond bog fire, RCMP are searching for a man who's connected to an encampment close to where the fire is believed to have been sparked.

Investigators also discovered ammunition and shell casings at the site, located at the north side of the forested area near Westminster Highway and Shell Road.

"We saw some remnants of an encampment.  It looks like [it's from] one individual who is known to police.  So RCMP are investigating for questioning.  We haven't seen anybody here who is from the encampment," said deputy chief Kevin Gray with the Richmond Fire Department on Saturday.

Officials stress the investigation into the cause of the fire is still in its early stages, and they are not calling it arson or a criminal matter at this stage.

The fire broke out Friday morning and has so far claimed an estimated 12 hectares of woodland -- but officials say it is now contained.

On Saturday, smoke from numerous wildfires also triggered a health advisory for eastern areas of Metro Vancouver and Fraser Valley. The fires have contributed to ground-level ozone -- a pollutant that can cause health risks, particularly for seniors and those with serious respiratory conditions.

The high concentration of ozone is expected to persist for several days, and add to the already hazy skies troubled by other fires in the Pacific Northwest.

The fire is close to suburban Richmond homes and prompted the BC Wildfire Service -- more often known for dousing remote area fires -- to scramble several fire-fighting aircraft to douse the flames from above.

Fire crews say the fire is difficult to extinguish due to the peat moss, as it can smoulder underground for days or even weeks. That means crews have to unearth the plant material and extinguish it on both sides.

With files from Sarah MacDonald