By: Korie Marshall
May 14th, another wind storm whipped dust up the valley from the dry drawdown zone of Kinbasket Reservoir.
“Is there any worry of us breathing this stuff in all the time?” asked Curtis Pawliuk while looking at the dust from up Swift Creek on Thursday afternoon. “It’s weird thinking about my kids playing outside at school right now. I just got back from a bike ride and I’m sure I can feel it.”
“As I drive to the mill site [in Cedarside], it is very obvious the dust from the upper end of Kinbasket is covering the entire valley to Tete Jaune, Dunster and McBride,” says Janey Weeks. She recalls there was local interest in a man-made lake at the upper end of the reservoir at one time, and thinks that would help mitigate the dust issue. The reservoir was created by Mica Dam as part of the Columbia River Treaty with the United States. The reservoir and generating station at Mica Dam is managed by BC Hydro. “BC Hydro should be concerned about the air quality – the village, the people,” says Weeks.
“You can’t make it 300 meters past the bridge on the west side,” says Erik Myggland, who was recreating down the lake when the dust storm kicked up. “The dust is so thick it unsafe to drive,”
But it’s not just a problem of not being able to see through the dust.
Owen Torgerson, president of the Valemount Marina Association, recently had to submit a silica exposure plan as part of the association’s bid to maintain the boat launch ramp for BC Hydro. (The association is trying to raise funds to replace the docks). Volunteers or contractors have to wear special masks when cleaning silt from the ramp, moving and loading rock, and all sorts of maintenance work because the silt and dust around the lake contains silica.
WorkSafeBC says silica is a common substance, found in sand, rock, and building materials like concrete and brick.
“Cutting, grinding, or drilling these materials releases dangerous crystalline silica dust into the air,” says the WorkSafeBC website. They’ve just released a two-minute video showing how silica exposure can permanently damage your lungs. It’s available at http://www2.worksafebc.com/Publications/Multimedia/Videos.asp?ReportID=36018.
WorksafeBC offers a guide to helping employers develop a silica exposure program. It says BC’s Occupational Health and Safety Regulation lists an occupational exposure limit for respirable crystalline silica of 0.025 milligrams per cubic metre. “This is a concentration to which nearly all workers could be exposed for eight hours a day, five days a week, without adverse health effects.”
But the guide says there is one more problem with silica. “As a suspected carcinogen, crystalline silica is also an ALARA substance.” That means exposures must be reduced to levels “as low as reasonably achievable” below the occupational exposure limit.
Looking from a viewpoint west of Cedarside at the dust coming up the valley to blanket Valemount, Torgerson said “Silica Exposure Control Plan – right out the window.”
The PM10 reading from the Valemount Firehall air quality monitor at noon on Thursday was 67 (moderate) and rising at 1:00 pm. PM10 measures the number of particles in the air that are less than 10 micrometers in size. Some provincial air quality monitors in BC also measure PM2.5, which are even smaller particles that can travel much farther and stay in the air much longer than the PM10 particles, according to the US’s Environmental Protection Agency’s website on particulate matter.
Ralph Adams, air quality meteorologist for the Ministry of Environment says the PM10 monitor on the Valemount Fire Department measures the average mass concentration of particles each hour, but it doesn’t fractionate the compounds, so we don’t know how much silica might be in the air during a wind storm like this. He noted the wind was strong, and the PM10 reading reached around 80, but it was short lived.
“In terms of the big picture, these levels you experienced today were not high,” said Adams on Thursday. Kamloops for example gets levels in the order of 900 in similar events.
“In Kamloops, whenever there is a strong wind particularly from the south, there are several places we can see a large yellow plume of dust across the highway and across the river,” says Adams. “Because the particles are quite large, and the concentrations are quite high, they are very visible and easy to see.”
Adams notes the provincial medical officials and the Centre for Disease Control are the ones that set the health messaging for the province. They say there is enough concern when the 24-hour average gets to 50 that an advisory is issued, and most healthy people wouldn’t be affected at that level. The dust storm in Valemount only lasted about three hours before the PM10 readings dropped again.
Adams says he is surprised by WorkSafe BC’s number of 0.025 mg/m3 because that is actually half the recommended maximum for inside buildings and normally you have poorer air quality inside buildings than outside.
“The real concern for the healthy people is the very fine particles which are the products of combustion rather than the larger particles,” says Adams. “In many communities, for instance Kamloops, we are moving to measuring the smaller particles, the PM2.5 rather than the PM10.”
The objective of having the monitor in Valemount is to issue an advisory if required, says Adams, but to his knowledge it’s never been necessary except for blanket advisories for wildfires.
You can check out more information about air quality at www.bcairquality.ca or follow the link for the Valemount Firehall meter from our website at www.therockymountaingoat.com.