Meteorologists investigated a spike in particulate today as one of the sensors located at the health unit on Kalum St. indicated a rise above healthy levels.
On the Ministry of Environment website an air quality indicator showed levels of PM10, one of two classifications of particulate, in the red at 75 ug/m3, well above the air quality objective of 50 ug/m3.
The spike occurred between Monday, January 6 at 4 p.m. and ended Tuesday, January 7 at 2 p.m.
Skeena's air quality meteorologist Barry Watson, who is located in Smithers, was attempting to confirm the readings with what people here in Terrace were seeing over the last two days, to verify if it was indeed an air event and not a local disturbance of the sensor.
Watson said that gravel and salt that is crushed into dust on the roads can get spun into the air by traffic and can cause high levels of PM10.
He said that the level of PM10 would have been both visible and potentially an irritant to people who have asthma or other lung conditions.
“You don't typically see that unless you have had a real cold snap and no precipitation,” said Watson.
He added that industrial traffic in the west end of town would be the most likely source, but that any dust would have been visible, and he has heard no reports of that, and is not issuing an air quality advisory unless the levels spike again.
“There is no corroborating evidence, no other source at this point to say 'why did it do that,'” Watson said of the high reading that has since dropped to normal levels.
“Weather conditions are likely to improve the situation moving forward, looking at the forecast,” he continued.
Overall, the type of particulate that the second sensor picks up, PM2.5, which is much finer and can enter deeper into the lungs, is a more serious concern than PM10.
Watson said that PM2.5 levels remained the same during the period when the other kind of particulate was being sensed at higher levels.
He said a disturbance on the roof of the health centre, such as sweeping, could have caused the temporary spike.