Trussville City Schools will limit students’ outdoor activities due to possible harm from smoke and airborne pollutants drifting over the area from a landfill fire in St. Clair County.

The fire in Moody has been burning for over a month. Residents across the Birmingham metro area have complained about nausea, headaches and coughing from the smoke.

According to a statement released by Superintendent Frank Costanzo, the school district made the decision following discussions with Mayor Buddy Choat and the Jefferson County Health Department and St. Clair County Emergency Management Agency.

“Following those discussions and advice, I wanted to let you know that we are working with the Jefferson County Health Department to secure air quality monitors at each school. Until we receive an all clear, we will take the necessary precautions to help ensure the safety of our students, including limiting all outdoor activities,” the statement read.

AL.com’s calls to school officials were not immediately returned Tuesday.

Read more: The Moody landfill fire is still burning. Now what?

The St. Clair County Commission declared a state of emergency Tuesday to take more aggressive efforts to extinguish the underground fire at the Environmental Landfill near Moody.

The fire, which is mostly burning underground, was first reported to the Moody Fire Department Nov. 25 and has blanketed a large area of Birmingham’s northern suburbs with smoke, creating concern over what those residents are breathing in.

Smoke from landfill fires often contains particulate matter which can aggravate existing pulmonary conditions and cause respiratory distress, according to a study by the Federal Emergency Management Agency. Underground fires, like the one in Moody, can also dangerously increase the levels of carbon monoxide in the air which deprives vital organs of oxygen.

James Mulkey, a fire inspector with the Moody Fire Department told AL.com in December that their best estimates were that the fire spanned between 23 and 50 acres and could be burning in layers of waste covered with dirt up to 150 feet deep in the site.

Trussville City Schools is encouraging students with respiratory issues to stay indoors, and is asking parents to let their school nurse know of any medication on hand to treat their child’s condition.