People with asthma or heart and lung problems are being advised to stay indoors because of forest fire smoke in the air.

Dr. Bryce Larke, the territory's medical health officer, is advising people to keep windows closed and fans circulating.

'We recognize this is not going to be possible for everyone because of jobs and or other circumstances,' he said in a statement earlier this afternoon.

The smoke carries particles of ash from the burned wood that, when breathed in, can cause respiratory irritation, Larke said.

Larke said those without underlying conditions can also be affected by heavy smoke from forest fires, but added the effects aren't life-threatening.

At most, people might have burning eyes, a dry throat and cough, he said.

'If people start experiencing extreme problems, they need to call their doctor, the health centre or go to the hospital,' said Larke.

Whitehorse General Hospital has not seen any increase in patients with respiratory illnesses, he added.