As locals prepare to celebrate Clean Air Day tomorrow, a layer of smoke from forest fires burning in Quebec compelled the city’s medical officer of health to issue a smog advisory yesterday.

According to the Ontario Ministry of the Environment’s air quality index, the air in Ottawa reached a very poor level by 10 a.m. The ministry says very poor air can have serious respiratory effects, even during light physical activity.

“What is in the air right now is a component of smog. It is called fine particulate matter,” said Jean-Guy Albert, a program manager with Ottawa Public Health.

Air quality in Ottawa varies from year to year, said Albert. The city is really a victim of weather and the industrial activity in southern Ontario and the United States.

According to Mike Buckthought, the co-ordinator of the Commuter Challenge in Ottawa-Gatineau, the forest fires, smog and last week’s record high temperatures are all signs of climate change.

“These are things we expect to see more of in the future if we don’t do something about it,” he said.

An easy way to fight climate change is to use sustainable transportation, Buckthought said.

Held to coincide with Environment Week, the Commuter Challenge encourages people to use sustainable modes of transportation, including walking, cycling and public transit.

Last year, 44,500 challenge participants nationwide, 2,600 of which were in Ottawa, reduced greenhouse gas emissions by an estimated 655 tons.

The city is also marking Clean Air Day tomorrow with an event at city hall at noon. Coun. Clive Doucet, in collaboration with the Netherlands Embassy, is hosting the event, which includes the best-dressed bicycle commuter contest and speaker Cathy Anderson, one of five cyclists struck by a minivan while cycling on March Road in Kanata last year.