Airline secondhand tobacco smoke (SHS) exposure is significantly related to worse respiratory health, even decades after exposure has ended, according to findings published recently in Chest. Although less severe, SHS is linked with airflow abnormalities used to diagnose chronic obstructive pulmonary disease (COPD).
Estimates place SHS exposure worldwide at 1.8 billion people, resulting in more than 600,000 deaths annually, according to the World Health Organization. SHS-exposure remains rampant in nightclubs, bars, casinos, homes, and vehicles across the US despite public smoking bans. Prospective consequences for respiratory health and development of COPD long-term are unclear. Researchers sought to test the hypothesis that decades after exposure ends, SHS exposure is associated with poor respiratory health and decreased lung function.
To accomplish this, they performed a prospective cohort study from 2015 through 2020 that included a group of 183 participants with more than 1 year of airline SHS-exposure (at least 50 years of age, mean 66.7 years; 90.7% female; hired at 23.8 years of age; exposed to 16.1±9.3 years of airline SHS; exposure stopped 27.5±9.4 years prior to study enrollment). Participants were mostly flight attendants recruited from United, Capital, Pan American, Continental, Trans World, Delta, Southwest and Alaskan Airlines. The study also included a cohort of 59 participants, unexposed, and mostly non-flight attendants.
All participants were encouraged to enroll whether or not they experienced symptoms. Participants who were exposed were older, more likely to be female, and had a lower BMI, compared to participants who were unexposed.
The primary study outcome was respiratory quality-of-life measured by the St. George’s Respiratory Questionnaire (SGRQ) score. The RAND Corporation-36 questionnaire (RAND-36), COPD Assessment Test (CAT), and spirometry represented secondary outcomes. SHS-exposure was not associated with differences in comorbidities, smoking history, or race/ethnicity compared with participants in the unexposed cohort.
Researchers found that respiratory quality of life, as measured by SGRQ, was significantly worse in the SHS-exposed group (by 6.7 SGRQ units; 95% CI, 2.7-10.7; P =.001). General quality of life, as measured by the RAND-36 physical and social function, and respiratory symptoms, as measured by CAT, were also worse in the SHS-exposed group. Pre-bronchodilator (BD) spirometry or obstruction was not affected by SHS-exposure, but exposure was associated with lower pulmonary function test scores in some SHS-exposed individuals for post-BD forced expiratory volume in 1 second (FEV1), FEV1/forced vital capacity (FVC), total lung capacity (TLC), and diffusing capacity of the lungs for carbon monoxide (DLCO). SHS-exposure and former smoking interactively worsened SGRQ (Beta = 8.4; 95% CI, 0.4-16.4; P =.04). For participants who never smoked, SHS exposure replicated primary results, associated with worsened SGRQ (4.7-units; 95% CI , 0.7-7.0; P =.006).
“Study findings show that SHS-exposure is associated with worsened respiratory health decades after exposure has ceased. In contrast, the impact of SHS-exposure on lung function, while present, was less robust,” the researchers concluded. Although airflow limitation could not be consistently detected, SHS exposure was variably associated with significant decreases in airflow, and researchers concluded that SHS worsens respiratory health. The effects of intense SHS-exposure are significant and do not resolve with time in a large percentage of people, making them worthy of attention by medical providers, scientists and funding agencies,” the researchers said.
Study limitations included: 1) low enrollment; 2) primarily female participants, limiting generalizability to males; 3) a control group that included mostly non-flight attendants; 4) imbalances in BMI and incidence of parental smoking during pregnancy were greater in the control group.
Diaz Del Valle F, Zakrajsek JK, Min SJ, et al. Impact of airline secondhand tobacco smoke exposure on respiratory health and lung function decades after exposure cessation. Chest. Published online March 7, 2022. doi:10.1016/j.chest.2022.02.049