When you can see the air that you breathe, chances are there is a problem.

That's what is happening in Prince George and several other Central Interior B.C. cities.

For the third straight day, a dust advisory remains in effect due to high levels of particulate matter.

People with chronic breathing problems are being advised by the B.C. Ministry of Environment and Northern Health not to engage in strenuous physical activity until the advisory has been lifted.

Similar advisories are in effect in Quesnel. Williams Lake, Smithers, Houston and Burns Lake and dusty conditions are expected to persist through the weekend.

The City of Prince George now has bylaws in place that prohibit all open burning, including backyard burning and land-clearing burning. During air quality advisories, there is a prohibition on all recreational fires, street sweeping activities, and the use of wood-burning appliances with the exception of homes whose sole heat source is wood stoves. Industrial sources of air pollution are asked to reduce emissions where possible during air advisories.

Sunny and dry conditions are expected to persist until Sunday in Prince George, with a high of 5 C expected Saturday. Winds out of the south are expected to peak at 20 kilometres per hour overnight Friday and most of the day Saturday, which might help clear the air. A daytime high of 6 C is predicted for Saturday. After an overnight low of -2 C, cloud will return Sunday and there's a 60 per cent chance of flurries with a high of 4 C forecast.