Emergency services are responding to a fire at Western Junction, near the Launceston Airport.
Twelve crews and four heavy tankers, seven light tanks, four medium tankers and one aircraft are battling the fire, and a TFS spokesperson said they were "knocking it down".
Smoke in Northern Tasmania on Monday is believed to have travelled from Victoria, a TFS spokesperson said.
"I don't actually think that's us," she said.
There are unhealthy levels of air pollution in Launceston, Ti Tree Bend, Lilydale, and Exeter.
There is moderate air pollution in Scottsdale, Hadspen, Oatlands, Sheffield, and New Norfolk.
The smoke has not affected flights.
The Western Junction blaze was first reported at 12.27pm and has burned at least 10 hectares.
It is believed to have been caused by a property-owner using a slasher in a paddock.