The Hamilton fire department has issued a ban on open air burning in light of the smog advisory in effect for the city.

The Ministry of the Environment issued the smog advisory on Tuesday. That means permit holders for open air burning are not allowed to use them.

This includes burning wood and brush, outdoor campfires and outdoor wood burning fireplaces. The ban will stay in place until the smog advisory is lifted.

Forest fires in Quebec are partially responsible for the poor air quality, the ministry says.

The advisory is in place for Halton-Peel, Toronto and York-Durham. Hamilton has one of the highest readings in the province.

"East to northeasterly flow of polluted air from forest fires in Quebec is resulting in high smog levels over eastern and parts of southern Ontario today," the advisory reads.

Hamilton's air is currently rated as poor, with the highest smog rating in the province as of Wednesday afternoon. Hamilton Mountain had a rate of 60 (with 50 to 99 being "poor"), downtown 58 and Hamilton west at 55.

The advisory will remain in effect until further notice.

A smog advisory is related to the air quality index (AQI), which rates how clean the air is. Higher AQI numbers mean high health risks.

A smog advisory is issued when the AQI is expected to reach 50 in the next 24 hours. Downtown Hamilton currently sits at 61, while Hamilton Mountain is at 50 and Hamilton west is at 53.

Smog is made up of a complex mixture of air pollutants that may or may not be visible. Its main ingredients are ground-level ozone and fine particular matter.