Exposure of Children and Adolescents to Passive Smoking in Cars

A school survey in 14 German federal states

In adults, passive smoking is associated with cancers, cardiovascular disorders, stroke, chronic obstructive pulmonary disease, type 2 diabetes, and asthma; in children it is associated with infections of the lower respiratory tract, middle ear infection (otitis media), asthma, sudden infant death, and low birth weight (1). Methodologically robust prospective cohort studies capturing exposures to passive smoking in childhood and cancer or cardiovascular disorders in adulthood are lacking. Retrospective cohort studies and case-control studies that analyze such associations have to be considered critically in view of their methods.

Tobacco smoke settles on surfaces and clings to walls, furniture, and clothing. Such deposits remain after airing and contain chemicals that are potentially harmful to health, but their long term health sequelae remain largely unknown (2).

In Germany, smoking on public transport is banned, but it is allowed in private cars. We investigated how many adolescents are currently affected by exposure to passive smoking in cars and what additional factors are associated with such exposures.

Methods

The data stem from the ninth collection of the Präventionsradar (prevention radar, www.praeventionsradar.de), a questionnaire study in school years 5–10, which was carried out nationwide (except for the federal states of Saarland and Bavaria) from November 2024 to February 2025. 116 schools with 1712 classes took part. Participation was voluntary; one class per year group was sufficient. The classes were equally distributed over the year groups. Students in the classroom independently completed an online questionnaire covering different health topics. Weighting factors were applied to adjust the data for the distribution of the baseline population of students as regards age, sex, and school type.

The primary endpoint of the study was the item “How often have you traveled in a car where someone was smoking?” Response options were available on a five-point Likert scale: “never”, “rarely”, “occasionally/sometimes”, often”, “very often”. In order to generalize the results from the sample to the total population of all adolescents in Germany, we extrapolated the data. To this end, we extrapolated the collected data on the basis of the official population figures from the German Federal Statistical Office from 2023.

To analyze correlates of passive smoking exposure this item was dichotomized. Adolescents who reported having traveled in a car in which someone was smoking “often” or “very often” were coded as exposed to passive smoking (=1); all others were coded as not exposed or only slightly exposed (=0). Furthermore we used the MacArthur scale (3) to record participants’ age, sex, type of school attended, subjective social status, and we recorded adolescents’ own nicotine consumption (e-cigarettes, cigarettes). The regional socioeconomic deprivation at the level of the 116 participating schools was determined on the basis of data from the Robert Koch-Institute (4).

Associations between passive smoking exposure and further variables were analyzed by using a multilevel logistic model, which took into account the clustered data structure by including the individual level (level 1) and the class level (level 2). We used a random intercept model to account for dependencies of the observations within the classes. We used Stata (version 19.0) to analyze the data.

Results

Of the 26 586 survey participants, 25 066 posted responses regarding passive smoking exposure in the car. Missing values (n=1520) were excluded from the analysis. Participants’ mean age was 13.2 years (standard deviation [SD]=1.78; range 9–17 years), 52% of participants were female. 52.7% of adolescents had never traveled in a car where someone was smoking (Table 1). 10.9% reported having been exposed to passive smoking in the car often or very often. Extrapolated to the population, this equals more than 750 000 children and adolescents.

Table 1

Passive smoking exposure in adolescents (9–17 years) in the car

Correlates of passive smoking exposure in the car

Passive smoking exposure in the car correlated positively with a greater life age of the children as well as with a lower social status; it was seen more rarely in those attending university preparatory high school. Adolescents who were exposed to passive smoking in the car consumed more nicotine products themselves and resided in regions with greater social deprivation. We did not see any differences between sexes (Table 2).

Table 2

Correlates of the passive smoking exposure of adolescents (9–17 years) in the car

Discussion

Three quarters of a million of adolescents aged 9–17 years were “often” or “very often” exposed to passive smoking in the car. Those not attending university preparatory high school were particularly affected, who themselves categorized their social status as low, who lived in regions with greater social deprivation, who were older, or who consumed nicotine products themselves. The results are based on questionnaire data, and response biases may exist. An ecologic error is possible since socioeconomic deprivation was not recorded at the individual level but at the school level. Furthermore, we did not collect exposure to exhaled air from e-cigarette consumption, which most probably is also harmful to health (5). The data collections did not take place in all federal states [Länder], so that the extrapolation to the total population of all 9–17 year olds has to be regarded as a rough approximation and not as an absolutely valid estimate.

England, Belgium, France, Greece, Ireland, Italy, Austria, Slovenia, and Wales have banned smoking in cars where minors are present, some also when pregnant women are present. In view of the health harms that can be associated with exposure to passive smoking and of the large number of those affected, a smoking ban in cars when minors or pregnant women are present should be introduced in Germany too.

Reiner Hanewinkel, Julia Hansen

Institut für Therapie- und Gesundheitsforschung, IFT-Nord gGmbH, Kiel (Hanewinkel, Hansen), [e-mail]

Funding

The study was funded by the DAK Gesundheit, one of the largest German statutory health insurers.

Ethics approval

The ethics committee of the Germany Society for Psychology approved the study as “ethically safe” (AZ RH 042015_1) on 15 June 2016. The responsible supervisory authorities—that is, the culture and education authorities—examine the conducting of the investigation, technically and pertaining to data protection.

Conflict of interest statement
RH is active as a volunteer in the Aktionsbündnis Nichtrauchen (ABNR, an association of non-governmental health organizations in Germany that combine their political activities in the area of promoting non-smoking and protection from the dangers of passive smoking).

JH declares that no conflict of interest exists.

Manuscript received on 21 July 2025, revised version accepted on 23 October 2025.

Translated from the original German by Birte Twisselmann, PhD.

Cite this as:
Hanewinkel R, Hansen J: Exposure of children and adolescents to passive smoking in cars: A school survey in 14 German federal states. Dtsch Arztebl Int 2026; 123: 61–2. DOI: 10.3238/arztebl.m2025.0197

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