The thick layer of smoke that blanketed the foothills on Monday caused concern for many residents.

Alberta Health Services issued a special air quality statement, which has since been lifted, as local ratings on Health Canada's air quality health index got quite high.

Brian Proctor, meteorologist with Environment Canada, says typically the air quality health index is impacted by nitrogen dioxide from fuels being burnt as well as the ozone, but locally it was forest fires that led to high ratings.

"What is driving the air quality health index at this point in time is forest fire smoke so that's what's really pushing those values up and we start seeing 7+ values, things are getting a little bit towards the high end of the risk and if we see 10 plus values, which likely at times in the Foothills we did, things were getting quite difficult for people that have breathing problems."

He says a change in flow pattern in the upper atmosphere is responsible for sending the smoke our way.

"Instead of having a south westerly flow loft, the big upper ridge centred across sort of eastern BC and western Alberta, we've now actually got a bit of a north westerly flow loft and some cooler air has spilled in," he explains. "The north westerly winds have allowed that smoke to build up in the Chilcotin plateau and also in sort of the Golden area to come across the Rockies and surface on our side."

Proctor adds instability in the atmosphere will help mix the smoke up a bit so it's not as concentrated Tuesday as what the Foothills experienced on Monday.