Preplanned Studies: Cigarette Use and Secondhand Smoke Exposure Among Secondary School Students — China, 2023

Tobacco use and exposure to secondhand smoke are the most preventable risk factors for adverse health outcomes. In children and adolescents, the initiation of smoking is linked with increased risks of nicotine dependence and subsequent mortality from tobacco-related diseases (1–2). Furthermore, there is no safe level of exposure to secondhand smoke (3), which not only heightens the likelihood of smoking initiation (4) but also adversely affects cardiovascular health and increases cancer mortality among non-smokers (5–6). The China CDC conducted the China National Youth Tobacco Survey (NYTS) targeting students in junior high school (JHS), senior high school (SHS), and vocational senior high school (VSHS) in 2019 and 2021, with a subsequent survey implemented in 2023. This study provides national-level data on experimental, current, frequent, and daily cigarette use, along with secondhand smoke exposure, from the 2023 China NYTS. Additionally, it examines provincial variations in current cigarette usage and secondhand smoke exposure within school environments.

The 2023 China NYTS adopted a design analogous to that used in the 2019 and 2021 iterations, incorporating a three-stage stratified cluster sampling method across Mainland China’s 31 provincial-level administrative divisions (PLADs). This approach ensures both national and provincial representativeness. Initially, five urban districts and five rural counties were selected from each PLAD using proportional population size (PPS) sampling. Within each chosen district or county, three JHSs, two SHSs, and one VSHS were selected using a student-based PPS sampling method. Subsequently, in the selected schools, one class comprising over 40 students from each grade level was randomly chosen to participate in the survey (7). A total of 261,455 students — comprising 134,769 JHS, 87,088 SHS, and 39,598 VSHS students — were ultimately surveyed, achieving an overall response rate of 95.7%. The survey protocol was approved by the Institutional Review Board of the China CDC under approval number 202301.

Experimental cigarette use was evaluated by inquiring whether participants had ever tried smoking cigarettes, even if only taking one or two puffs. Those who answered affirmatively were categorized as experimental users. Current users were defined as individuals who reported smoking at least once in the past 30 days. Within this group, frequent users were identified as those who smoked on 20 or more days, and daily users were defined as those who smoked every day. The study further investigated exposure to secondhand smoke across various environments, including homes, indoor and outdoor public places, and public transportation. Participants were asked to report the number of days in the preceding week during which they were in the presence of someone smoking in each of these environments. Exposure to secondhand smoke was characterized by the presence of a smoker at least one day during the prior week. Additionally, the study assessed secondhand smoke exposure in school environments by asking participants whether they had observed smoking on school premises, both inside buildings and on other property, within the last month. Regular occurrences of teachers smoking in both indoor and outdoor school settings were examined by querying the frequency of such instances over the last 30 days.

Data were adjusted to accommodate the complex sampling design. Prevalence estimates, accompanied by their 95% confidence intervals (CIs), were calculated. The Rao-Scottχ²test was employed to assess differences between subgroups, with a 2-tailedPvalue of <0.01 deemed statistically significant. All analyses were conducted using SAS software (version 9.4, SAS Institute Inc., Cary, NC, USA).

In 2023, the prevalence of experimental cigarette use among secondary school students was reported at 13.7%, with 4.2% of students currently smoking, 1.2% smoking frequently, and 0.8% reporting daily smoking. Male students exhibited higher rates of smoking (19.1%, 6.4%, 2.0%, and 1.4%, respectively) compared to their female counterparts (7.8%, 1.8%, 0.3%, and 0.2%, respectively). The highest rates of smoking were observed among VSHS students (22.3%, 9.6%, 3.6%, and 2.6%, respectively), followed by SHS students (14.7%, 3.8%, 1.3%, and 0.9%, respectively), and the lowest in JHS students (11.2%, 3.1%, 0.6%, and 0.4%, respectively). In JHS, the prevalence of experimental and current smoking was higher in rural areas (12.3% and 3.8%) compared to urban areas (9.9% and 2.3%) (Table 1). Variability in current cigarette use among PLADs ranged from 0.9% in Zhejiang to 12.6% in Xizang, with higher prevalence rates observed in the southwestern (Xizang, Yunnan, Guizhou, and Chongqing PLADs) and the southern-central regions (Hainan and Henan PLADs), as well as in Qinghai Province. For JHS, the prevalence ranged from 0.4% in Zhejiang to 10.7% in Xizang; in SHS, it ranged from 0.8% in Zhejiang to 12.5% in Xizang; and in VSHS, it ranged from 2.6% in Jiangxi to 25.4% in Yunnan, with over 10% prevalence in 17 out of 31 PLADs (Figure 1).

Figure 1.

Provincial disparities in the prevalence of current cigarette use among secondary school students in China by school type, 2023.

In the same year, 54.5% of secondary school students reported exposure to secondhand smoke within the preceding seven days across four distinct locations. The highest incidences were observed in outdoor public places (40.2%) and indoor public spaces (37.5%). Exposure rates were comparatively lower at home (29.4%) and on public transportation (20.2%). Boys experienced higher rates of exposure than girls in all settings, and urban areas exhibited increased exposure rates at home and in both indoor and outdoor public spaces relative to rural areas (Table 2).

Approximately 35.4% of secondary school students reported exposure to secondhand smoke on school premises over the past 30 days, with prevalence higher among boys (40.7%) than girls (29.5%). Students in SHS and VSHS reported significantly higher rates of exposure (42.0% and 42.5%, respectively) compared to those in JHS (30.2%), without marked differences between urban and rural areas. Notably, 8.3% of students observed teachers smoking in schools almost every day during the past 30 days; this incidence was higher among boys (11.1%) than girls (5.3%), and more common in rural areas (9.5%) compared to urban locations (7.1%). Among student categories, SHS attendees (10.9%) reported higher rates compared to JHS peers (6.9%). Significant geographical disparities were observed in the prevalence of secondhand smoke exposure within schools across different PLADs, ranging from 23.3% in Shanghai to 51.0% in Chongqing. A higher prevalence was noted particularly in the southwestern (Chongqing, Xizang, and Yunnan PLADs) and central regions (Hubei, Hunan, and Anhui PLADs). For JHS students, exposure rates varied from 18.4% in Inner Mongolia to 46.8% in Chongqing; for SHS students, they ranged from 25.2% in Shanghai to 58.0% in Hubei; and for VSHS students, from 26.7% in Xinjiang to 54.3% in Chongqing. It is significant that the prevalence exceeded 40% in 13 out of the 31 PLADs among VSHS students, a figure substantially higher than those observed for JHS and SHS students (Figure 2).

Figure 2.

Provincial disparities in the prevalence of secondhand smoke exposure at schools among secondary school students in China by school type, 2023.