Thirdhand smoke (THS) is defined as residual tobacco components that remain on indoor surfaces after tobacco has been smoked, such as walls furniture,and dust particles, which are re-emitted into the air. THS also includes secondary pollutants generated from the reaction of surface residual smoke compounds with reactive indoor air pollutants. THS is a new hidden health hazard, with infants and children being most at risk of higher exposure. This article summarized the aging process of secondhand smoke and the mechanism of generation of THS;reviewed the current status of research on THS regarding its chemical constituents, physical and chemical properties, biological toxicity, as well as degree of pollution in China and other countries;and finally provided the perspectives on the future study of THS.

Thirdhand smoke (THS) is defined as residual tobacco components that remain on indoor surfaces after tobacco has been smoked, such as walls furniture,and dust particles, which are re-emitted into the air. THS also includes secondary pollutants generated from the reaction of surface residual smoke compounds with reactive indoor air pollutants. THS is a new hidden health hazard, with infants and children being most at risk of higher exposure. This article summarized the aging process of secondhand smoke and the mechanism of generation of THS;reviewed the current status of research on THS regarding its chemical constituents, physical and chemical properties, biological toxicity, as well as degree of pollution in China and other countries;and finally provided the perspectives on the future study of THS.

Thirdhand smoke (THS) is defined as residual tobacco components that remain on indoor surfaces after tobacco has been smoked, such as walls furniture, and dust particles, which are re-emitted into the air. THS also includes secondary pollutants generated from the reaction of surface residual smoke compounds with reactive indoor air pollutants. THS is a new hidden health hazard, with infants and children being most at risk of higher exposure. This article summarized the aging process of secondhand smoke and the mechanism of generation of THS; reviewed the current status of research on THS regarding its chemical constituents, physical and chemical properties, biological toxicity, as well as degree of pollution in China and other countries; and finally provided the perspectives on the future study of THS.
Adolescent ; Air Pollution, Indoor ; Child ; Child, Preschool ; China ; Dust ; Environmental Exposure ; Humans ; Infant ; Infant, Newborn ; Research ; Smoke ; Tobacco Smoke Pollution

OBJECTIVETo investigate thirdhand smoke (THS) pollution in certain places of Nanjing, as well as to analyze its distribution characteristics.

METHODSFrom March to May, 2014, we selected 3 types of places (residencies, public places and transportation vehicles) that were close to people's living in Jianye,Yuhua,Jiangning,Xuanwu,Gulou and Pukou districts of Nanjing city.For each of the above 3 types of places, 2-3 smoking and non-smoking (smoking ban) locations were investigated, totally 51 locations, 9-10 samples were collected each location, totally 477 samples. The surface wipe sampling method in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was utilized to quantify the levels of nicotine that served as the tracer of THS pollution.One-way ANOVA and t-tests were employed to compare the levels of nicotine collected at different places and locations.

RESULTSTotally 477 samples were collected in this study, of which 27.0% was from residencies (129/477), 61.0% (291/477) from public places and 11.9% (57/477) from transportations. The levels of indoor surface nicotine in smoking residences, public places and transportations were (214 ± 55),(1 408 ± 177) and (1 511 ± 785) µg/m(2), respectively, which were all higher than those in the corresponding non-smoking places ((23 ± 9),(62 ± 11), and (46 ± 15) µg/m(2); t values were 13.79, 13.15, 3.45, respectively. P values were <0.001, <0.001 and 0.006, respectively).In the smoking places, the levels of surface nicotine on walls, desks, sofas, cabinets, door backsides and air conditioning openings were (171 ± 62),(232 ± 38),(373 ± 151),(903 ± 239), (978 ± 212), (1 721 ± 517) µg/m(2) (F = 7.06, P = 0.009).In the smoking condition, the levels of surface nicotine collected from public places were higher (F = 9.25, P = 0.024), while under non-smoking (smoking ban) conditions, the levels of surface nicotine collected from residences were lower (F = 7.88, P < 0.001).

CONCLUSIONTHS pollution was widespread in public places, residences and transportations in Nanjing city, which was more serious in the smoking environments than non-smoking (smoking ban) environments; the contamination was less serious in non-smoking (smoking ban) private residences; in the smoking condition, the levels of surface nicotine were relatively high at locations close to air conditioning openings, door backsides and cabinets.

Air Conditioning ; China ; Housing ; Humans ; Nicotine ; Public Facilities ; Smoking ; Tandem Mass Spectrometry ; Tobacco Smoke Pollution ; Transportation