by Andru McCracken
Three factors work in combination to make Valemount’s air quality the worst measured in the province, according to Gail Roth, an air quality meteorologist based in Prince George. Roth presented her data at the Air Quality and Health Forum at the Valemount Community Hall on October 27.
The first factor is topology – the mountains around us, the second meteorology – local weather patterns, and third, the lack of natural gas and resulting reliance on wood heat.
On a series of slides created from data measured on top of the Valemount Fire Hall, it’s clear that air pollution in Valemount is at its worst in winter. And typically, if a good wind is present air quality is quite good.
The problem is that often times there is a stable air mass sitting above Valemount that prevents any wind whatsoever, leading to a buildup of pollution. Roth’s graphs show a correlation between zero wind speeds and high levels of air pollution.
Roth said fewer daylight hours and colder temperatures result in less mixing. That means wood smoke filled air doesn’t get replaced.
“When sunlight hits the ground it starts heating things up,” she explained. “That causes eddies.”
These eddies can rise up and create turbulence, and on a good air quality day that turbulence will get big enough that the dirty smoky air from town will leave the valley, allowing pollutants in the air to escape, she explained.
Roth said concentrations of air pollution typically decrease during the day, because they rise in the atmosphere.
“Sometimes the pollutants won’t fully escape the valley. It can actually get mixed down again,” she said.
“Valemount is also in this valley so you get shorter daylight hours.
She said the colder it gets the more wood burning, the more smoke, and less dispersion.
She said that communities on a prairie or next to the ocean may have an advantage, but they can still have air quality issues.
“On Vancouver island there are some communities where residential woodsmoke is the major cause of pollution,” she said.
Roth said there is no magic bullet, but that there is a suite of things that could be looked at.
“It’s not about saying you can’t burn wood,” she said.
Next week we’ll look at easy, practical solutions to reduce the amount of pollution in Valemount.