More people died from an opioid overdose in Nassau and Suffolk counties in 2016 than ever before, according to new data released by the medical examiner’s office. The reports revealed 493 deaths. At least 85 cases are still under investigation.

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In Suffolk County, a record 303 people died from an opioid overdose, including 171 related to fentanyl, a painkiller that is 50 times more potent than heroin. Compare that to 2015, when 86 people died from a fentanyl-related overdose.

Nassau County lost 190 people to an opioid overdose, up from 177 in 2015. The medical examiner tied 62 of those deaths to fentanyl.

Fentanyl is now Long Island’s deadliest drug, outpacing even heroin. It killed at least 220 people last year, compared to 93 heroin overdoses.

Long Island’s issues with fentanyl are part of a growing national epidemic. In New Hampshire, 158 people overdosed on the drug in 2015.

Long Island Pulse will delve further into the fentanyl epidemic in May.