Ottawa firefighters hazardous materials investigators and paramedics returned to a waste facility after workers twice complained about air quality.

Firefighters first responded Friday morning to the BFI waste transfer facility 2628 Glenfield Dr. after half a dozen workers reported feeling ill.

The building was evacuated but firefighters said whatever caused the illness likely dissipated and was no longer in the building.

Then shortly after 1 p.m. the Hazmat team was called back to the scene to perform more air quality testing after workers at the facility again called 911 and complained about nausea.

Firefighters again found nothing toxic or hazardous but they did say there appeared to be an irritant likely from the garbage, which workers were sorting.

The Ministry of Labour was also on site.