"What's that funky smell?"
"It's the smell of money being made."
If you haven't heard that conversation around Prince George lately, you're not alone. This winter, people have been doing a lot less complaining about our city's air quality.
Is it because the obvious industrial sources of air pollution have cleaned up their act? It's partly that, according to meteorologist Dennis Fudge, the provincial government's watchdog on Prince George air quality, but we've also had the weather on our side.
For a city that sometimes suffers from its geography, surrounded by hills that trap air pollutants, cold stationary fronts offer the perfect recipe for a bad air day. But this has been one of the mildest winters in more than a decade and we've had more than the usual share of windy days. Consequently, there have been no air quality advisories since Nov. 1-3.
"It's been real good air quality for the month of February, and if you think about it we haven't had any real cold spells since mid-November," said Fudge. "We haven't had any minus-30 temperatures this winter. When you get cold air like that, everything gets trapped in the airshed and more people are keeping their houses warm with woodstoves to keep warm and more cars are idling."
Despite the good winter, Fudge said the past year's PM2.5 levels of fine particulate pollution from combustion (vehicle exhaust, industrial smoke, wood and agricultural burning) were on average worse than they were in 2011. Early August brought a series of air quality advisories and Fudge said the daily PM2.5 readings for September, October and November readings were not very good. The difficulty is pinpointing what causes the levels to rise.
"You don't know whether it had to do with meteorology because if you get stagnant conditions or winds blowing form the pulp mills to the monitor, you'll start noticing it with high levels [of pollution]," said Fudge.
"The fine particulate levels increased in 2012, but in 2011 we had a lot more windier, wet conditions [which clean the air] and we had record low particulate levels in Prince George. July 2011 was one of the coldest, wettest on record. So even though the numbers increased for 2012, they're still lower than they were the previous three years."
Eight air quality advisories were issued in 2012, three because of road dust, two due to forest fires and three because of fine particulates. In 2011, there were just two advisories. From March 2011 to February 2012, there were no advisories. During an air quality advisory, when PM levels exceed 50 micrograms per cubic metre, the city prohibits all open burning, including backyard bonfires and land-clearing burning, and offers free rides on city buses.
Stinky days because of total reduced sulphur (TRS) typically become noticeable in late morning when air that gets heating by the sun starts to rise and replaced by heavier polluted air from smokestacks that has accumulated overnight. The increased smell is a sign the inversion that trapped the foul air is starting to break.
Cooler air is heavier and as it sinks it creates an air flow along the river valleys, which drags foul-smelling air emitted from pulp mill and refinery stacks and from low-level sources like the sewage treatment plant. For residents who live close to the rivers, that becomes more noticeable on foggy days, especially at night and early in the morning.
"Most people notice the odour, they don't notice the particulate matter as much, which is the real health concern, and we do have elevated levels compared to most places in Western Canada," said UNBC environmental science professor Peter Jackson.
"If you look at PM2.5 levels, which are the smaller particles and can go deeper into the lungs, there's a slight downward trend over the past 10 or 15 years. There's a lot of variation from year to year because of the weatherm but we think levels are getting better."
Some of the decreased fine particulate levels can be attributed to pollution control upgrades at the three city pulp mills, the Husky Oil refinery and the asphalt plants, which responded to public pressure to filter emissions.
To address the smell issue and also increase capacity to burn more wood to make power and steam for increased energy efficiency, Canfor took advantage of the federal government's $1 billion Pulp and Paper Green Transformation Program funding to complete the first of several pollution control upgrades in April 2011. Several other upgrades were introduced, further reducing PM2.5 and TRS emissions.
At the Husky Oil refinery, sulphur recovery units were installed in 1997 and 2006 to reduce sulphur content in fuels made at the plant, which significantly reduced the plant's four odour emissions. While it is the smallest oil refinery in Canada, Husky was identified in 2007 as the city's largest source of sulphur dioxide pollution.
"They aren't a big emitter of particulate matter, they emit more gases than particles," said Jackson. "There is some stinky stuff, some reduced sulphur coming from them but not large compared with the pulp mills, which are the major source of odour in the airshed."
The fire and explosion last April that destroyed the Lakeland Mills sawmill and shut down the Lakeland planer mill could contribute to lower PM2.5 levels. But Fudge said it will be difficult to determine how much of an effect the loss of the Lakeland mill will have on the city's airshed because some of the improved pollution controls at the pulp mills became operational around the same time.
"When you get two or three changes being made, you don't know whether [the Lakeland mill closures] made a difference or not,," said Fudge. "When the North Central Plywood plant burned down [in May 2009] there was a big difference in the BCR monitoring station the following year and that was mainly because the plant was the closest source to the monitors. It was a combination of the emissions from the plywood plant and the trucking activity in the yard and the dust from that. Once that plant burned down that made a big drop in particulate levels."
Increased train traffic means more diesel locomotive exhaust coming from the downtown CN Rail yard and that contributes to the PM2.5 readings. But in the big picture, only about 20 per cent of the city's PM2.5 pollution is from industrial sources.
"The rest of it is coming from us, burning firewood in our fireplaces or driving our cars," said Jackson. "Even if no humans were here, we'd still have a quarter of the PM2.5 we have now, from dust and biogenic emissions like pollens, so we can only control 75 per cent of it."
With spring approaching, elevated PM10 levels (mostly from road dust) will become noticeable in Prince George over the next few weeks. Fudge said city road crews made significant improvements in reducing dust, especially in the downtown area, by using calcium chloride instead of sand to prevent icing conditions. City bylaw that came into effect with the Clean Air Act require all road sweepers to first apply water before they clean streets or parking lots.
Monitoring stations at the Prince George Regional Correction Centre, BCR industrial site, Lakewood subdivision, and downtown at Plaza 400 measure PM2.5, PM10 and TRS levels, and also measure the levels of 200 volatile organic compounds.
Jackson and his UNBC air pollution class are now working with Fudge on a study to determine how to increase the accuracy of the process of testing filters used to measure particulate levels. The study will determine the role humidity condensate plays in adding weight to the filters when they are brought in from cold conditions into a warm room.