City officials announced on Thursday that they had confirmed the first vaping-related death in the District. The D.C. Department of Health did not provide details on the death, except to say that it was related to vaping.

Since October 22, there have been 1,604 confirmed cases of lung injury associated with vaping, per the Centers for Disease Control (which uses “e-cigarette” and “vaping” interchangeably—confused? Here’s a primer). Cases have been reported in every single state except Alaska, as well as D.C. Thirty-four people have died from the lung illness so far, according to the CDC.

The exact cause of the illness is still unclear, though it appears that black market THC products pose the highest risk for illness. “The latest national and state findings suggest products containing THC, particularly those obtained off the street or from other informal sources (e.g. friends, family members, illicit dealers), are linked to most of the cases and play a major role in the outbreak,” the CDC said on its website Thursday.

The lung injury associated with vaping products started just this year, even though e-cigarettes have been on the market for about a decade now. Patients with the illness are mostly young men, and many of them developed acute respiratory distress syndrome, where fluid build-up in the lungs prevents oxygenation (see this comprehensive breakdown on the illness and some of its earliest victims in the Washington Post).

The first death from the illness was reported back in August in Illinois.

Doctors and public health officials are still trying to figure out exactly what compounds are causing the injury, which has left some sickened patients on respirators and in intensive care units. “No one compound or ingredient has emerged as the cause of these illnesses to date; and it may be that there is more than one cause of this outbreak,” the CDC says. ” Many different substances and product sources are still under investigation. The specific chemical exposure(s) causing lung injuries associated with e-cigarette product use, or vaping, remains unknown at this time

The CDC recommends against using vaping products, particularly those that contain THC. Jurisdictions throughout the region have begun tightening restrictions on the purchase and sale of vaping products. The D.C. Council is considering two measures to crack down on vaping, as well.

The following symptoms are associated with vaping-related lung injury, per the D.C. DOH:

• Frequently reported symptoms include shortness of breath, cough, chest pain, nausea, diarrhea, or vomiting
• Many patients have reported initial symptoms such as unexplained weight loss, fatigue, abdominal pain, or fever
• Severe cases have required admission to the hospital
• Some patients have reported that their symptoms developed over a few days, while others have reported that their symptoms developed over several weeks. A lung infection does not appear to be causing the symptoms.

If you think you may be experiencing vaping related illness, you can call the National Capital Poison Control Center at (800) 222-1222.