Secondhand Marijuana Smoke

Secondhand cannabis smoke from a bong is more dangerous than cigarette smoking, according to researchers.

In a study published Wednesday in the journal JAMA Network Open, authors from the University of California, Berkeley School of Public Health wrote that bong smoking “is not safe.”

“Decades ago, many people thought [secondhand tobacco smoke (SHTS)] presented no health risk to nonsmokers. Scientific research since then changed this perception and led to smoke-free environments. Incorrect beliefs about [secondhand cannabis smoke (SHCS)] safety promote indoor cannabis smoking,” they said.

“Nonsmokers are exposed to even higher concentrations of SHCS materials during ‘hot-boxing,’ the popular practice in which cannabis smokers produce high volumes of smoke in an enclosed environment. This study’s findings suggest SHCS in the home is not safe and that public perceptions of SHCS safety must be addressed.”

The group found that concentrations of fine particulate matter (PM2.5) generated in a home during social cannabis bong smoking to which a nonsmoking resident might be exposed were greatly increased compared with background levels, and that PM2.5 decayed only gradually after smoking ceased.

Following 15 minutes of smoking, average PM2.5 was more than twice the Environmental Protection Agency (EPA) hazardous air quality threshold.

“If one assumes the exposure concentrations were at the mean levels observed, a single home smoking session with no other exposures would generate an estimated mean daily concentration that greatly exceeds the average in cigarette-smoking homes, nonsmoking homes and the U.S. EPA daily standard,” the researchers said.

In order to reach these conclusions, the Environmental Health Sciences Division members’ levels of PM2.5 were measured before, during and after eight cannabis social-smoking sessions in a household living room.

An aerosol monitor was placed where a nonsmoker might sit to record the levels.

Home cannabis bong smoking significantly increased PM2.5 from background levels by at least 100-fold to 1,000-fold for six of eight sessions. The other two sessions had high background levels and significantly increased PM2.5 more than 20-fold.  READ MORE...