What influences thirdhand smoke exposure


Thirdhand smoke exposure poses a health threat to children. New research examines the factors that may lead to some children having more exposure than others.

The decrease in traditional tobacco smoking and the enacting of laws that restrict smoking in public spaces has led to significant reductions in firsthand and secondhand smoke exposure. However, thirdhand smoke exposure (meaning contact with smoke residue on surfaces and in dust where smoking previously occurred) remains a problem, particularly for children, because of higher intake in comparison to adult body weight, immature immune systems and other factors. A recent research letter looks into the proportion of children aged younger than 12 years who were exposed to thirdhand smoke in the absence of secondhand smoke as well as what factors are linked to this exposure.1

The investigators screened children aged younger than 12 years who were seeking emergency care as well as the children of employees at the Cincinnati Children’s Hospital Medical Center in Ohio between February 2020 and May 2021. Investigators interviewed the parents and wiped the palmar and volar surfaces of all fingers on the children’s dominant hands. Protection from exposure to tobacco was given to children if no household member smoked or vaped, smoking and vaping were banned in homes and cars, and there was no contact with tobacco users within the previous week. The hand wipes were analyzed to determine the presence of nicotine on the children’s hands.

The cohort included 504 children with an average age of 5.7 years. Nicotine was found on the hands of 189 children who were exposed to tobacco and 296 children who had reported been protected from tobacco exposure. The presence of nicotine on the hand had significant ties to parent tobacco use, the number of tobacco users the child spent time with, and home smoking rules. The highest levels of nicotine on the hand were seen in in children who had parents who used any form of tobacco products, lived in places without complete smoking bands, and had multiple contacts that used tobacco. Children from the lowest annual income (≤$15,000) and second-lowest annual income ($15,001-$30,000) levels had 5.7 times and 1.7 times higher levels of hand nicotine than children from households with an annual income greater than $30,000. Similarly, children in Black households had higher nicotine levels than children in White and multiracial households.

The investigators concluded that the high level of thirdhand smoking exposure among children is of concern. Protecting children from exposure did not fully insulate children but did lessen the exposures found. Implementing exposure screening and remediation programs to remove thirdhand smoke from environments when an occupant moves could protect children from unnecessary and potentially harmful exposure.


1. Matt G, Merianos A, Quintana P, Hoh E, Dodder N, Mahabee-Gittens E. Prevalence and income-related disparities in thirdhand smoke exposure to children. JAMA Netw Open. 2022;5(2):e2147184. doi:10.1001/jamanetworkopen.2021.47184

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