A recent study found COVID-19 has been associated with a 52% increase in opioid overdoses among non-Hispanic Black residents in Philadelphia, NPR reports. The study adds to evidence that overdose deaths have disproportionately affected Black Americans.

The study found COVID-19 was associated with decreases in opioid overdoses among non-Hispanic white residents.

Researchers noted the pandemic has exacerbated stressors, social isolation and economic deprivation disproportionately in Black communities, possibly contributing to increased substance use. “The pre-existing racial disparities in accessing substance use treatment may also be heightened by COVID-19–related shifts in treatment availability,” the researchers wrote in the Journal of the American Medical Association.

“It wasn’t until we started looking at the level of race and ethnicity that we realized Black and brown communities are being disproportionately affected,” lead researcher Dr. Utsha Khatri of the University of Pennsylvania told NPR. “COVID really just acted as salt in the wounds of health and social inequities, perpetuated by structural racism both in Philadelphia and across the country.”