Grand Forks, Castlegar had highest soot levels in B.C. in 2020

Grand Forks and Castlegar had the highest soot levels in B.C. last year, thanks largely to wildfire smoke, according to the B.C. Lung Association (BCLA) and B.C.’s environment ministry.

Statistics compiled in the association’s latest State of the Air Report show that on average, Grand Forks’ skies held nearly 12.5 micrograms of fine particulate matter (FPM) per cubic metre (μg/m³⁾ every day in 2020 — around 1.5 times the province’s annual objective of 8 μg/m³ per day. The air in Castlegar held a daily average of around 11 μg/m³ in the same period, or around 1.4 times the annual objective.

READ MORE: Grand Forks had second-highest smog levels in B.C. last year

Donna Haga, Senior Air Quality Meteorologist at B.C.’s environment ministry, defined FMP as any airborne particle less than 2.5 micrometres across. Haga said these tiny specks are mostly put into the air by wildfires and wood-burning stoves as well as engine exhaust and certain types of industry.

For context, Haga said health authorities issue air quality advisories at FPM concentrations higher than the province’s average daily objective of 25 μg/m³, qualifying that FPM can be harmful to people’s health at any concentration.

FPM levels peaked in both cities for a week and a half last September, when Haga said large swathes of Southeastern B.C. were blanketed in smoke from wildfires then burning in California. In that time, average daily levels topped out at 375 μg/m³ in Grand Forks and 424 μg/m³ in Castlegar.

On those days, residents experienced FPM levels of between 15 and 17 times higher than the provincial daily objective, Haga explained. Grand Forks skies exceeded the daily objective on four other days between January and February, statistically the coldest months of the year, when people are most likely to burn wood for heat and in November, when she said many communities in Southeastern B.C. allow open burns.

At between 26.5 to 35 μg/m³, Haga pointed out that those levels were considerably lower than the spikes recorded during last year’s peak wildfire season.

“When you wrap up the data over the course of a year, it’s the high values that really influence a yearly report,” she said. Excluding wildfire smoke, both Grand Forks’ and Castlegar’s average annual FPM levels fell within provincial objectives between 2017-2019, according to an environment ministry report.

Sarah Henderson, scientific director of Environmental Health Services at the BC Centre for Disease Control, put the point more succinctly in late June, when a centre news release quotes her as saying that, “In 2017, 2018 and 2020, we experienced consecutive days and weeks of the worst air quality that most people will ever experience in British Columbia.”

Among the harmful effects of wildfire smoke, the news release goes on to note that, “Fine particulate matter carries the greatest risk to human health as it can be inhaled deep into the lungs and cause inflammation and irritation.”

Haga meanwhile explained that, while geography and prevailing weather patterns factored into last year’s FPM levels in Grand Forks and Castlegar, “There are pretty clear links between increased wildfire activity in the region and climate change.”

“We had wildfires before climate change was such a strong focus, but it’s hard to deny it’s had increased impacts on wildfire seasons even in the last four or five years,” she noted.

Grand Forks had the second-highest soot levels in B.C. in 2019, according to the BCLA’s 2020 State of the Air Report.

@ltritsch1 laurie.tritschler@grandforksgazette.caLike us on Facebook and follow us on Twitter.