Smoking and the effects of second hand smoke, particularly on children, have been making the headlines recently. UK MPs voted in favour of new laws to ban smoking by adults in cars when they are travelling with children.
Strong evidence shows that second-hand smoke is dangerous, but new research is now revealing a new danger – third-hand smoke. Dr Michael Beckles
, Respiratory Medicine specialist at The Physicians’ Clinic, investigates.
“Everyone knows that cigarette smoking is bad for you. Studies show that smoking cessation could potentially lead to the saving of nearly 6 million deaths worldwide, and could save over 100,000 deaths in the UK every year and could prevent smoking related disease in 2 million people,” he reports.
Explaining types of smoking exposure
Cigarette smoke exposure may be further classified as either first-hand, second-hand or third-hand.
“First-hand cigarette smoke (FHS) exposure describes smoke exposure from the inhaled smoke from a burning cigarette. Second-hand cigarette smoke (SHS) describes exposure to exhaled smoke from a burning cigarette, and smoke from the filter or mouthpiece end of a cigarette.”
“A new type of smoking exposure has recently been described: third-hand smoke exposure (THS). THS describes the environmental exposure that occurs after someone else has been smoking; it is often smelled, but cannot be seen. It is left behind in the environment in which smoking has occurred, and is made up from pollutants that remain in the environment, or that react with environmental nitrous oxide to form carcinogenic substances.”
Worryingly, the substances from cigarette smoking are left behind in dust and on deposits that cling to surfaces in the home, such as work surfaces, chairs, doors and door handles and tables – even toys.
“This third-hand smoke can be picked up by other people and can have effects on health long after active cigarette smoking has ceased.”
The new research on third-hand smoke
THS is now an area of growing research, particularly since Martins–Green et al
. published their latest findings in the journal PLoS ONE
“The research demonstrated that THS leads to an increase in lipid levels in the body and a higher risk of developing non-alcoholic fatty liver disease. Some of the components stimulate excess collagen production in the lung, and also increase levels of inflammatory cytokines.”
THS also has damaging effects on wounded skin, with surgical incisions showing much longer healing. Behavioural tests have shown that TSH-exposed mice become hyperactive.
“If these findings are replicated in humans, that means serious implications for human health. Human exposure to THS pollutants has not yet been thoroughly studied, but the Martins–Green research suggests that we may need to change our attitudes to smoking rooms in hotels, public venues where smoking has occurred, and when purchasing houses and cars, for example. It may be that this research will lead to more research into how cleaning might be able to reduce the impact of THS.”