On Friday, smoke could be seen rising from a salvage yard fire still burning in Martensville. (Dan Shingoose/CTV News)

As a salvage yard fire in nearby Martensville continued to burn Friday evening, Saskatchewan's Ministry of Environment issued an air quality advisory for Saskatoon.

"Smoke levels are expected to vary throughout the evening and through tomorrow morning, with heaviest impact to the northern regions of the city," a public safety alert sent to residents from the City of Saskatoon said.

"Visibility may be reduced on roadways and the smoke may pose respiratory and eye irritation."

In the alert, the city advises residents to prevent smoke from the entering their homes by keeping windows and doors closed and limiting the use of heating and ventilation systems.

"Elderly residents and people with compromised immune systems or respiratory issues are advised to take extra caution to prevent exposure to the smoke."

Martensville Fire Department and the Saskatchewan Public Safety Agency are working to extinguish the fire, the alert said.

The fire  — which has been burning for more than a day — was sparked Thursday after an ember from a controlled burn flew into a pile of demolition waste, according to a BN Steel & Metals Inc. employee who spoke to CTV News.