N.W.T.'s Chief Public Health Officer is warning people to avoid strenuous exercise outdoors with heavy smoke hanging over many communities in the southern part of the territory.

Forty-three wildfires are burning, the majority in the North and South Slave regions, blanketing Yellowknife and several other communities with smoke. 

Dr. Andre Corriveau says people who already have lung problems should stay inside with the windows closed.

He says if the smoke is thick enough to irritate people's eyes and throats, it is also irritating the lungs.

"For healthy people it doesn't really make a big difference, but for somebody who already has compromised lung function because of chronic obstructed lung disease — people with asthma, people with bronchitis — it can really make a big difference." 

Corriveau says the smoke can have more of an effect on elderly people. He encourages relatives and neighbours to check on them regularly.

To date this season in N.W.T., 56 fires have been started by lightning, 11 were human-caused and one near Yellowknife was started by an electrocuted raven.