A team of firefighters in the B.C. Lower Mainland is trying to beat down a fire that has torched an area two kilometres long and a one kilometre wide. Smoke from the blaze has covered the region.

Crews have massed at the edges of Delta's Burns Bog, trying to slow down the blaze burning just 25 kilometres southwest of downtown Vancouver.

The fire was first reported on Sunday, and barriers set up to contain the blaze failed. Water bombs called in Sunday night dropped a kilometre wide trail of retardant on the fringes, but were unable to prevent the fire from breaking through the barriers in a couple of places. The fire doubled in size overnight, growing from 12 to 23 hectares.

Many home owners are awaiting a one hour notice to evacuate that could come at any time. Tina Miller's farm backs onto the bog, and may have to flee with 40 horses.

"If the wind changes that means the smoke is coming this way," Miller said. "If the smoke comes this way we're going to have to leave."

In spite of the difficulties, firefighters on the scene are optimistic that they will soon have the perimeters established again. They say that the blaze is now 80 per cent contained.

Ground crews from the Delta Fire Department have joined forces with the B.C Forest Service, along with an array of air tankers and helicopters.

Delta Mayor Lois Jackson fears the damage caused by the fire will have long terms consequences. "It's unbelievable what the fire can do. You wonder how this will ever revive itself."

The wind is blowing the smoke eastward away from the water and highway, and so several neighbourhoods in the area are not being threatened. Thick plumes of smoke are visible across the Lower Mainland, and parked cars have been covered with ash.

With a white haze hanging in the air above Vancouver, a burning smell is also evident across the mainland. Fine particles discharged from the fire have rendered the air quality so poor that people have been calling 9-1-1 in droves to complain about the smoke.

Officials say there is no reason to panic, as breathing the smoke for a few days should not harm a healthy person. However, seniors and small children should take extra precautions to protect themselves. People are advised to keep windows closed, and to contact their doctor should they experience difficulty breathing.

The bog caught fire before. In 1996 a fire scorched 170 hectares and took two days to extinguish.

Burns Bog is a large undeveloped area that extends over 4,000 hectares, roughly 10 times the size of Vancouver's Stanley Park. It encompasses the largest undeveloped urban area in Canada and the largest wetland in the Fraser River delta.

It is home to various species including beaver, muskrat and Columbian black-tailed deer, and 150 species of birds. It is also the site of the largest garbage dump west of Toronto, according to DiscoverVancouver's website.

It is not known yet what sparked the blaze.