BRIDGETON, Mo. (AP) – St. Louis County Health Department says workers will conduct a health survey of respiratory ailments near the Bridgeton Landfill, where an underground fire has been smoldering since 2010.

The St. Louis Post-Dispatch (http://bit.ly/1SfkUbk ) reports that department director Faisal Khan said Monday that the survey would compare a random sample of residents living near the burning landfill to another group. The department wants to see if the underground fire may be causing an increase in respiratory ailments.

The cause of the underground fire is unknown.

Khan said the survey will look for asthma, chronic obstructive pulmonary disease and allergy conditions among the 4,300 households within a two-mile radius of the landfill. An exact start date for the survey wasn’t announced.

Republic Services, which owns the landfill, capped the landfill and installed emission control equipment in 2013.