Sarah Henderson doesn't want to ring the fire alarm bells just yet, but history is not on the side of B.C. Interior forests.
The 12-year pine beetle infestation has left dead trees standing like dry matchsticks and Henderson, an environmental health scientist with the B.C. Centre for Disease Control, is worried about the effects that kind of a smoke show will have on people.
"We have had four of the worst forest fire seasons in history over the last decade in British Columbia," said Henderson. "Part of that is because we have a lot of beetle-killed wood sitting around and that stuff just likes to burn. We're going to have more bad forest fires in years to come and it's important to understand that when we have a super smoky day in B.C., everyone is affected."
But as Henderson pointed out to the Civic Centre audience this past week at the North Central B.C. Clean Air Forum, because of geographical features, not all areas of the province are affected to the same degree by forest fire smoke, which carries fine particulates that can lodge in the lungs of people. Prince George, a city in the centre of the province surrounded by hills which tend to trap air in weather inversions, is especially vulnerable.
"In the Lower Mainland, we're not affected in the same way, we might see a 200 per cent increase [in PM2.5 levels] and an area like Prince George might see a 2,000 per cent increase," said Henderson. "Even though these things are episodic, they're unpredictable and don't happen that often, some of the highest short-term exposure to air pollution in the B.C. boondocks come from large forest fire events."
The provincial government estimates that from 2000-2012 the pine beetle epidemic killed 710 million cubic metres of pine timber, 53 per cent of the province's entire pine inventory. Dead pine trees burn hotter and are consumed more completely than live trees caught in a forest fire because the drier wood of the trunk tends to catch fire, rather than just the boughs and needles.
2010 was the worst fire season on record in B.C., but the last two years have been relatively calm. Fires burning in Siberia last August brought smoke to the Prince George area for about a week which raised PM2.5 levels but there were no serious forest fire incidents in the area.
During smoky days, asthmatics, heart patients, seniors and children are the most affected and hospital admissions and emergency room visits spike. Henderson said if the smoke gets bad she advises people to stay inside in air conditioned buildings as much as possible. She also recommends using portable high efficiency particulate air (HEPA) filtering units to clean smoky air that gets into houses.
"We don't like to push the onus on individuals but especially under unpredictable forest fire smoke conditions, people who know they have difficulty breathing when it's smoky need to be prepared at the beginning of the season for the possibility that it's going to be a retched awful forest fire season," Henderson said.
Complicating the problem forest fires pose is a more constant source of air pollution for many smaller B.C. communities -- resource-based industries. As Henderson pointed out, the livelihoods of many people in smaller B.C. cities are tied to industrial sources of air pollution like pulp mills, sawmills, refineries and smelters, which continually emit harmful particulates.
The abundance of trees in the province makes residential wood-burning appliances a cheap source of heat and not all of those stoves burn efficiently, adding to the air pollution problem, especially in winter during temperature inversions.
Tobacco use has become less prevalent in the Lower Mainland and Henderson said only about 15 per cent of the population in Greater Vancouver are now smokers, but in rural B.C., the number of smokers are more like 25 or 30 per cent of the population and in some places it's as high as 50 per cent.
"If you smoke, this is your number one source of air pollution exposure," said Henderson. "Compared with what's happening in your community and with wood stoves, it's the thing that affects you the most, and it affects your family and your friends if you're smoking around them."