Scientists have found a way to get rid of compounds that deposit on surfaces from third hand cannabis smoke

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Although there’s nothing quite like the stale smell that remains after smoking tobacco, weed smoke also deposits compounds on surfaces that new research suggests can be reduced by ozone, which is found in both indoor and outdoor air.

Plenty is known about second- and third-hand smoke (THS) — which are reactive chemicals that remain in the air or are deposited on surfaces like walls, windows, clothing and upholstery, respectively — from tobacco. The same cannot be said for cannabis smoke, which is less studied and chemically distinct from tobacco smoke.

To explore how ozone, a component found in both indoor and outdoor air, can react with the psychoactive cannabis compound tetrahydrocannabinol (THC), researchers coated glass and cotton cloth with a THC solution. They then exposed the surfaces to concentrations of ozone that could exist in indoor air.

Appearing in the American Chemical Society’s (ACS) publication, Environmental Science & Technology, the reaction between weed smoke and ozone produced “new compounds, which they characterized for the first time,” researchers report.

“Over time, the amount of THC on glass and cotton decreased, while the quantities of three THC oxidation products (identified in the study abstract as epoxide, dicarbonyl and secondary ozonide THC reaction products) increased,” according to the ACS. That is important since third-hand smoke “lingers long after a person stops smoking.”

The team also used a smoking machine to deposit cannabis smoke on cotton. / Photo: AaronAmat/Getty Images

The team also used a smoking machine to deposit cannabis smoke on cotton. When that was exposed to ozone, “the same three compounds formed at roughly the same rate as observed for the THC-coated cloth,” the ACS reports.

“Nicotine is semi-volatile and reacts with other chemicals on surfaces, producing new compounds that, if volatile, can also become airborne,” the society explains. But with regard to cannabis smoke, “because of the low volatility of THC and its oxidation products, the compounds are unlikely to be emitted to the air where they could be inhaled in as large amounts as nicotine,” it adds.

3D illustration of lungs - part of human organic.

Tobacco has more than 7,000 chemicals, hundreds of which are toxic and 70 that can cause cancer. / PHOTO BY YODIYIM / ISTOCK / GETTY IMAGES PLUS

The residue from THS builds up on surfaces over time, according to the Mayo Clinic. Advising that hard surfaces, fabrics and upholstery be regularly cleaned or laundered and airing out rooms by opening windows, using fans or air conditioners, the information adds “infants and young children might have increased exposure to third-hand smoke due to their tendency to mouth objects and touch affected surfaces.”

That dovetails with the new study, where researchers point out that exposure to THC and its derivatives, whose health effects are unknown, is possible. That would happen, for example, if a person licked his or her fingers after touching a surface contaminated by cannabis smoke.

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