A recent study suggests firefighters who fought the Horse River wildfire are suffering from persistent lung damage.

The University of Alberta’s occupational health research team remained in contact with over 1,200 individuals for roughly three years after the disaster.

They checked all of their lung functions and compared them to people around the same age, sex, and health status.

The study determined these firefighters have double the risk of developing asthma, lung hyperreactivity, and an increased thickening of the bronchial wall.

“The impact was correlated to exposure—those who had more exposure had more effects,” said Nicola Cherry, principal investigator.

The damage to these firefighters’ lungs is reportedly similar to the harm first responders of the 9/11 terrorist attacks currently suffer from.

This was somewhat surprising as the individuals who responded to the World Trade Center collapse were exposed to mainly inorganic dust, while local responders breathed in mostly organic particles.

“It’s interesting that we saw similar results from very different exposure,” added Cherry.

Moving forward, she plans on studying the health of the individuals who are currently fighting wildfires in Alberta and British Columbia.

The hope is these findings will help encourage better protection for first responders.