Never heard of third-hand smoke?
Researchers show why you should care
PHILADELPHIA – Dodging the clouds of toxic cigarette smoke along city streets and at building entrances has become the norm for those wanting to avoid the health risks from breathing in second-hand smoke.
But if you think being in a smoke-free building will shield you from the negative health effects of second-hand smoke, you are in for a surprise.
Now there is third-hand smoke: the residue that can be carried on clothing and hair or left behind on couches and counters long after cigarette smoke has cleared. Turns out toxic particles can be activated and released back into the air.
Researchers at Drexel University looked at how particles from outside air get inside and found a “chemical signature” that didn’t exist outdoors – which they identified as third-hand smoke, said Peter F. Decarlo, lead author of the study published Wednesday in Science Advances.
“It was a completely unexpected result,” said Decarlo, an associate professor of environmental engineering and chemistry.
Third-hand smoke particles can become reactivated when they come into contact with the natural ammonia that is emitted from the human body. Indoor temperatures and humidity also play a role in that process, making exposure more of an issue in summer months, he said.
The researchers tested the air of an unoccupied classroom where smoking had not been allowed in decades. They found that 29 percent of the indoor aerosol mass contained third-hand smoke particles. While particulate matter in air is a small fraction of what we breathe in, the worrisome factor was the concentration of contamination, Decarlo said.
Being in a room that is contaminated with third-hand smoke during an average workday is the equivalent of being in a room filled with second-hand smoke for about five minutes, he said.
Since the building was smokefree and there was no indication anyone was violating that policy, the researchers looked at possible other sources.
The room was down the hall from an outdoor balcony where people often go to sneak an illicit smoke. It was also part of the same heating, ventilation and air-conditioning zone as a nearby office space shared by several smokers, and the system recirculated contaminated air throughout the building.