Associations between respiratory illnesses and secondhand smoke exposure in flight attendants: A cross-sectional analysis of the Flight Attendant Medical Research Institute Survey

Impact of Airline Secondhand Tobacco Smoke Exposure on Respiratory Health and Lung Function Decades After Exposure Cessation

BACKGROUND

Twenty-five percent to 45% of COPD is caused by exposures other than active smoking. Secondhand tobacco smoke (SHS) has been suggested as an independent cause of COPD, based on its association with increased respiratory symptoms and a small decrease in lung function, but its impact on respiratory health and lung function after exposure cessation has not been explored.

RESEARCH QUESTION

What are the consequences of airline SHS exposure on respiratory health and lung function decades after cessation?

STUDY DESIGN AND METHODS

We performed a cohort study involving flight attendants because of their exposure to SHS that stopped > 20 years ago. We included subjects ≥ 50 years of age with > 1 year vs ≤ 1 year of airline SHS exposure (ie, exposed vs unexposed). Respiratory quality of life, as determined by the St. George's Respiratory Questionnaire (SGRQ), was the primary outcome for respiratory health. Key secondary outcomes included general quality of life (the Rand Corporation modification of the 36-item Short Form Health Survey Questionnaire; RAND-36), respiratory symptoms (COPD Assessment Test; CAT), and spirometry.

RESULTS

The study enrolled 183 SHS-exposed and 59 unexposed subjects. Exposed subjects were 66.7 years of age, and 90.7% were female. They were hired at 23.8 years of age, were exposed to airline SHS for 16.1 years, and stopped exposure 27.5 years before enrollment. Prior SHS exposure was associated with worsened SGRQ (6.7 units; 95% CI, 2.7-10.7; P = .001), RAND-36 physical and social function, and CAT vs unexposed subjects. SHS exposure did not affect prebronchodilator spirometry or obstruction, but was associated with lower postbronchodilator FEV1 and FEV1/FVC, total lung capacity, and diffusing capacity of the lungs for carbon monoxide in a subset of subjects. Former smoking and SHS exposure synergistically worsened SGRQ (β = 8.4; 95% CI, 0.4-16.4; P = .04). SHS exposure in people who never smoked replicated primary results and was associated with worsened SGRQ vs unexposed people (4.7 units; 95% CI, 0.7-7.0; P = .006).

INTERPRETATION

Almost three decades after exposure ended, airline SHS exposure is strongly and dose-dependently associated with worsened respiratory health, but less robustly associated with airflow abnormalities used to diagnose COPD.

Elastin Degradation and Lung Function Deterioration with Remote Secondhand Tobacco Smoke Exposure in Never-smokers

BACKGROUND

Prolonged past exposure to secondhand tobacco smoke (SHS) in never-smokers is associated with abnormal lung function and reduced diffusing capacity suggestive of an associated lung tissue injury and damage. The mechanisms by which past SHS exposure may contribute to lung tissue damage are unknown. Elastin is a major constituent of extracellular matrix in lung parenchyma.

OBJECTIVE

To determine whether past exposure to SHS is associated with ongoing lung tissue damage as indicated by elevated elastin degradation products that are linked to lung function.

METHODS

We measured the plasma levels of elastin degradation markers (EDM) from 193 never-smoking flight attendants with a history of remote SHS exposure in aircraft cabins and 103 nonsmoking flight attendants or sea-level control participants without such history of cabin SHS exposure and examined those levels versus their lung function with adjustment for covariates. The cabin SHS exposure was estimated based on airline employment history and years of the smoking ban enactment.

RESULTS

The median [interquartile range] plasma EDM level for all participants was 0.30 [0.24-0.36] ng/mL with a total range of 0.16-0.65 ng/mL. Plasma EDM levels were elevated in those with a history of exposure to cabin SHS compared to those not exposed (0.33±0.08 versus 0.26±0.06 ng/mL; age- and sex-adjusted P<0.001). In those with a history of cabin SHS exposure, higher EDM levels were associated with a lower diffusing capacity (parameter estimate [PE] 95% [confidence interval(CI)]=4.2 [0.4-8.0] %predicted decrease per 0.1 ng/mL increase in EDM; P=0.030). Furthermore, EDM levels were inversely associated with forced expiratory volume in 1 second (FEV₁), FEV₁ to forced vital capacity (FVC) ratio , and forced expiratory flow rate between 25% and 75% ( FEF_25%-75%) (PE [95%CI]=5.8 [2.1-9.4], 4.0 [2.2-5.7], and 12.5 [5.8-19.2] %predicted decrease per 0.1 ng/mL increase in EDM, respectively; P<0.001). Plasma EDM mediated a substantial fraction of the association of SHS with FEV₁, FVC, and FEF_25%-75% (P<0.05).

CONCLUSIONS

Long after past exposure to SHS, there is ongoing elastin degradation beyond what is expected from the aging process, which likely contributes to lower lung function and a reduced pulmonary capillary bed as seen in chronic obstructive pulmonary disease (COPD).

The Carcinogenic Properties of Overlooked yet Prevalent Polycyclic Aromatic Hydrocarbons in Human Lung Epithelial Cells

The WHO classified air pollution as a human lung carcinogen and polycyclic aromatic hydrocarbons (PAHs) are components of both indoor (e.g., tobacco smoke and cookstoves) and outdoor (e.g., wildfires and industrial and vehicle emissions) air pollution, thus a human health concern. However, few studies have evaluated the adverse effects of low molecular weight (LMW) PAHs, the most abundant PAHs in the environment. We hypothesized that LMW PAHs combined with the carcinogenic PAH benzo[a]pyrene (B[a]P) act as co-carcinogens in human lung epithelial cell lines (BEAS-2B and A549). Therefore, in this paper, we evaluate several endpoints, such as micronuclei, gap junctional intercellular communication (GJIC) activity, cell cycle analysis, anti-BPDE-DNA adduct formation, and cytotoxicity after mixed exposures of LMW PAHs with B[a]P. The individual PAH doses used for each endpoint did not elicit cytotoxicity nor cell death and were relevant to human exposures. The addition of a binary mixture of LMW PAHs (fluoranthene and 1-methylanthracene) to B[a]P treated cells resulted in significant increases in micronuclei formation, dysregulation of GJIC, and changes in cell cycle as compared to cells treated with either B[a]P or the binary mixture alone. In addition, anti-BPDE-DNA adducts were significantly increased in human lung cells treated with B[a]P combined with the binary mixture of LMW PAHs as compared to cells treated with B[a]P alone, further supporting the increased co-carcinogenic potential by LMW PAHs. Collectively, these novel studies using LMW PAHs provide evidence of adverse pulmonary effects that should warrant further investigation.

Vascular Aging Is Accelerated in Flight Attendants With Occupational Secondhand Smoke Exposure

OBJECTIVE

To determine whether early vascular aging may be present in flight attendants with remote in-cabin secondhand smoke (SHS) exposure.

METHODS

Twenty-six flight attendants with a history of in-cabin SHS exposure prior to the airline smoking bans were recruited. Pulse wave analysis, peripheral arterial tonometry, and brachial artery reactivity testing evaluated their arterial compliance and endothelial function.

RESULTS

Flight attendants with remote in-cabin SHS exposure have normal blood pressure, pulse wave velocity, and reactive hyperemia index, but abnormal pulse pressure, augmentation index, flow-mediated dilation, and hyperemic mean flow ratio.

CONCLUSION

These preliminary findings suggest that flight attendants with remote in-cabin SHS exposure have preclinical signs of accelerated vascular aging and raise new questions about the relationship between remote SHS exposure and vascular health.

Quenching the fires: Pro-resolving mediators, air pollution, and smoking

Exposure to air pollution and other environmental inhalation hazards, such as occupational exposures to dusts and fumes, aeroallergens, and tobacco smoke, is a significant cause of chronic lung inflammation leading to respiratory disease. It is now recognized that resolution of inflammation is an active process controlled by a novel family of small lipid mediators termed "specialized pro-resolving mediators" or SPMs, derived mainly from dietary omega-3 polyunsaturated fatty acids. Chronic inflammation results from an imbalance between pro-inflammatory and pro-resolution pathways. Research is ongoing to develop SPMs, and the pro-resolution pathway more generally, as a novel therapeutic approach to diseases characterized by chronic inflammation. Here, we will review evidence that the resolution pathway is dysregulated in chronic lung inflammatory diseases, and that SPMs and related molecules have exciting therapeutic potential to reverse or prevent chronic lung inflammation, with a focus on lung inflammation due to inhalation of environmental hazards including urban particulate matter, organic dusts and tobacco smoke.

High Prevalence and Clinical/Sociodemographic Correlates of Miscarriages Among Flight Attendants

BACKGROUND

There are many occupational health hazards associated with long hours of air travel, including cosmic radiation exposure, circadian rhythm disruptions, prior and secondhand smoke exposure, for flight attendants who flew before smoking bans were initiated in the 1990s. Previous studies in flight attendants have found increased incidence of breast cancer and melanoma. However, there is little information on the relationship of airline travel and reproductive health in flight attendants. Secondhand smoke exposure has numerous negative health effects, such as increased cardiac events and respiratory infections, but its effect on reproductive health is not known. This study seeks to examine the role of secondhand smoke exposure on the miscarriage rate in flight attendants who flew before the smoking ban.

METHODS

Flight attendants who flew before the smoking ban and participating in a study of health effects of secondhand smoke were asked to complete a reproductive health survey. We compared miscarriage rates of flight attendants to the general population using 2010 data from the Centers for Disease Control and Prevention.

RESULTS

In our cohort of 145 female flight attendants exposed to secondhand smoke, there were 45 miscarriages (26%), compared with a 17.1% rate in the Centers for Disease Control and Prevention report (P = .002). There was no difference in secondhand smoke exposure between the flight attendants with miscarriage and the group without miscarriage (P = .93).

CONCLUSIONS

This study found an increased incidence of miscarriage in flight attendants, which was unrelated to secondhand smoke exposure. Other factors, such as circadian rhythm disruption and radiation, may be related to these reproductive health findings and require further investigation.

Understanding the impact of second-hand smoke exposure on clinical outcomes in participants with COPD in the SPIROMICS cohort

BACKGROUND

Second-hand smoke (SHS) exposure has been linked to the development of and morbidity from lung disease. We sought to advance understanding of the impact of SHS on health-related outcomes in individuals with COPD.

METHODS

Among the participants with COPD in SPIROMICS, recent SHS exposure was quantified as (1) hours of reported exposure in the past week or (2) reported living with a smoker. We performed adjusted regression for SHS with outcomes, testing for interactions with gender, race, smoking and obesity.

RESULTS

Of the 1580 participants with COPD, 20% reported living with a smoker and 27% reported exposure in the past week. Living with a smoker was associated with worse St George's Respiratory Questionnaire score (SGRQ, β 3.10; 95% CI 0.99 to 5.21), COPD Assessment Test score (β 1.43; 95% CI 0.52 to 2.35) and increased risk for severe exacerbations (OR 1.51, 95% CI 1.04 to 2.17). SHS exposure in the past week was associated with worse SGRQ (β 2.52; 95% CI 0.47 to 4.58), nocturnal symptoms (OR 1.58; 95% CI 1.19 to 2.10), wheezing (OR 1.34; 95% CI 1.02 to 1.77), chronic productive cough (OR 1.77; 95% CI 1.33 to 2.35) and difficulty with cough and sputum (Ease of Cough and Sputum scale, β 0.84; 95% CI 0.42 to 1.25). SHS was associated with increased airway wall thickness on CT but not emphysema. Active smokers, obese individuals and individuals with less severe airflow obstruction also had higher susceptibility to SHS for some outcomes.

CONCLUSION

Individuals with COPD, including active smokers, have significant SHS exposure, associated with worse outcomes and airway wall thickness. Active smokers and obese individuals may have worse outcomes associated with SHS.

TRIAL REGISTRATION NUMBER

NCT01969344 (clinicaltrials.gov).

Clear Skies and Grey Areas: Flight Attendants' Secondhand Smoke Exposure and Attitudes toward Smoke-Free Policy 25 Years since Smoking was Banned on Airplanes

Our objective was to provide descriptive data on flight attendant secondhand smoke (SHS) exposure in the work environment, and to examine attitudes toward SHS exposure, personal health, and smoke-free policy in the workplace and public places. Flight attendants completed a web-based survey of self-reported SHS exposure and air quality in the work environment. We assessed the frequency and duration of SHS exposure in distinct areas of the workplace, attitudes toward SHS exposure and its health effects, and attitudes toward smoke-free policy in the workplace as well as general public places. A total of 723 flight attendants participated in the survey, and 591 responded to all survey questions. The mean level of exposure per flight attendant over the past month was 249 min. The majority of participants reported being exposed to SHS always/often in outdoor areas of an airport (57.7%). Participants who worked before the in-flight smoking ban (n = 240) were more likely to support further smoking policies in airports compared to participants who were employed after the ban (n = 346) (76.7% versus 60.4%, p-value < 0.01). Flight attendants are still being exposed to SHS in the workplace, sometimes at concerning levels during the non-flight portions of their travel. Flight attendants favor smoke-free policies and want to see further restrictions in airports and public places.

Impact of cabin ozone concentrations on passenger reported symptoms in commercial aircraft

Due to elevated ozone concentrations at high altitudes, the adverse effect of ozone on air quality, human perception and health may be more pronounced in aircraft cabins. The association between ozone and passenger-reported symptoms has not been investigated under real conditions since smoking was banned on aircraft and ozone converters became more common. Indoor environmental parameters were measured at cruising altitude on 83 US domestic and international flights. Passengers completed a questionnaire about symptoms and satisfaction with the indoor air quality. Average ozone concentrations were relatively low (median: 9.5 ppb). On thirteen flights (16%) ozone levels exceeded 60 ppb, while the highest peak level reached 256 ppb for a single flight. The most commonly reported symptoms were dry mouth or lips (26%), dry eyes (22.1%) and nasal stuffiness (18.9%). 46% of passengers reported at least one symptom related to the eyes or mouth. A third of the passengers reported at least one upper respiratory symptom. Using multivariate logistic (individual symptoms) and linear (aggregated continuous symptom variables) regression, ozone was consistently associated with symptoms related to the eyes and certain upper respiratory endpoints. A concentration-response relationship was observed for nasal stuffiness and eye and upper respiratory symptom indicators. Average ozone levels, as opposed to peak concentrations, exhibited slightly weaker associations. Medium and long duration flights were significantly associated with more symptoms compared to short flights. The relationship between ultrafine particles and ozone on flights without meal service was indicative of ozone-initiated chemistry.

Modeling flight attendants' exposure to secondhand smoke in commercial aircraft: historical trends from 1955 to 1989

Flight attendants were exposed to elevated levels of secondhand smoke (SHS) in commercial aircraft when smoking was allowed on planes. During flight attendants' working years, their occupational SHS exposure was influenced by various factors, including the prevalence of active smokers on planes, fliers' smoking behaviors, airplane flight load factors, and ventilation systems. These factors have likely changed over the past six decades and would affect SHS concentrations in commercial aircraft. However, changes in flight attendants' exposure to SHS have not been examined in the literature. This study estimates the magnitude of the changes and the historic trends of flight attendants' SHS exposure in U.S. domestic commercial aircraft by integrating historical changes of contributing factors. Mass balance models were developed and evaluated to estimate flight attendants' exposure to SHS in passenger cabins, as indicated by two commonly used tracers (airborne nicotine and particulate matter (PM)). Monte Carlo simulations integrating historical trends and distributions of influence factors were used to simulate 10,000 flight attendants' exposure to SHS on commercial flights from 1955 to 1989. These models indicate that annual mean SHS PM concentrations to which flight attendants were exposed in passenger cabins steadily decreased from approximately 265 μg/m(3) in 1955 and 1960 to 93 μg/m(3) by 1989, and airborne nicotine exposure among flight attendants also decreased from 11.1 μg/m(3) in 1955 to 6.5 μg/m(3) in 1989. Using duration of employment as an indicator of flight attendants' cumulative occupational exposure to SHS in epidemiological studies would inaccurately assess their lifetime exposures and thus bias the relationship between the exposure and health effects. This historical trend should be considered in future epidemiological studies.

A review of smoking policies in airports around the world

Objective

To review smoking policies of major international airports, to compare these policies with corresponding incountry tobacco control legislation and to identify areas of improvement for advancing smoke-free policy in airports.

Methods

We reviewed smoking policies of 34 major international airports in five world regions, and collected data on current national and subnational legislation on smoke-free indoor places in the corresponding airport locations. We then compared airport smoking policies with local legislation. Additionally, we collected anecdotal information concerning smoking rules and practices in specific airports from an online traveller website.

Results

We found that 52.9% of the airports reviewed had indoor smoking rooms or smoking areas; smoking policy was unknown or unstated for two airports. 55.9% of the airports were located in countries where national legislation allowed designated smoking rooms and areas, while 35.3% were in smoke-free countries. Subnational legislation restricted smoking in 60% of the airport locations, while 40% were smoke-free. 71.4% of the airport locations had subnational legislation that allowed smoke-free laws to be more stringent than at the national level, but only half of these places had enacted such laws.

Conclusions

Despite the increasing presence of smoke-free places and legal capacity to enact stricter legislation at the local level, airports represent a public and occupational space that is often overlooked in national or subnational smoke-free policies. Secondhand smoke exposure in airports can be reduced among travellers and workers by implementing and enforcing smoke-free policies in airports. Additionally, existing information on smoke-free legislation lacks consistent terminology and definitions, which are needed to inform future tobacco control policy within airports and in the law.

The self-reported health of U.S. flight attendants compared to the general population

BACKGROUND

Few studies have examined the broad health effects of occupational exposures in flight attendants apart from disease-specific morbidity and mortality studies. We describe the health status of flight attendants and compare it to the U.S. population. In addition, we explore whether the prevalence of major health conditions in flight attendants is associated with length of exposure to the aircraft environment using job tenure as a proxy.

METHODS

We surveyed flight attendants from two domestic U.S. airlines in 2007 and compared the prevalence of their health conditions to contemporaneous cohorts in the National Health and Nutrition Survey (NHANES), 2005-2006 and 2007-2008. We weighted the prevalence of flight attendant conditions to match the age distribution in the NHANES and compared the two populations stratified by gender using the Standardized Prevalence Ratio (SPR). For leading health conditions in flight attendants, we analyzed the association between job tenure and health outcomes in logistic regression models.

RESULTS

Compared to the NHANES population (n =5,713), flight attendants (n = 4,011) had about a 3-fold increase in the age-adjusted prevalence of chronic bronchitis despite considerably lower levels of smoking. In addition, the prevalence of cardiac disease in female flight attendants was 3.5 times greater than the general population while their prevalence of hypertension and being overweight was significantly lower. Flight attendants reported 2 to 5.7 times more sleep disorders, depression, and fatigue, than the general population. Female flight attendants reported 34% more reproductive cancers. Health conditions that increased with longer job tenure as a flight attendant were chronic bronchitis, heart disease in females, skin cancer, hearing loss, depression and anxiety, even after adjusting for age, gender, body mass index (BMI), education, and smoking.

CONCLUSIONS

This study found higher rates of specific diseases in flight attendants than the general population. Longer tenure appears to explain some of the higher disease prevalence. Conclusions are limited by the cross-sectional design and recall bias. Further study is needed to determine the source of risk and to elucidate specific exposure-disease relationships over time.

The role of secondhand smoke in sinusitis: a systematic review

BACKGROUND

The objective of this study was to systematically review existing literature on the association between sinusitis and secondhand smoke (SHS) exposure.

METHODS

We performed a literature search encompassing the last 25 years in PubMed, EMBASE, and Cochrane CENTRAL. Inclusion criteria included English language papers containing original human data with at least 7 subjects. Data was systematically collected on study design, patient demographics, clinical characteristics/outcomes, and level-of-evidence (Oxford Center for Evidence-Based Medicine). Quality assessment was performed using the Newcastle-Ottawa scale. Two investigators independently reviewed all manuscripts.

RESULTS

The initial search yielded 116 abstracts, of which 19 articles were included. Thirteen (68.4%) of the 19 articles showed a statistically significant association between sinusitis and SHS. Seven (36.8%) studies specifically evaluated chronic rhinosinusitis (CRS) with 5 (71.4%) CRS studies demonstrating a significant association between CRS and SHS. Seventeen articles were case-control studies (Level 3b). For characterizing sinusitis, 6 (31.6%) studies included computed tomography (CT) or endoscopy in the diagnostic criteria, with 5 of these studies following rhinosinusitis taskforce guidelines. For determining presence of SHS, all studies used questionnaires and 2 (10.5%) studies also reported serum or urine cotinine levels.

CONCLUSION

A majority of the studies (68.4%) included in this systematic review showed a significant association between sinusitis and SHS. Furthermore, 5 (83.3%) of the 6 studies with objective diagnostic criteria (CT, endoscopy) found a significant association between sinusitis and SHS. Further higher-quality studies with objective diagnosis of sinusitis and quantification of SHS exposure should be performed in the future to better evaluate the relationship between sinusitis and SHS.

Non-IgE-mediated and irritant-induced work-related rhinitis

PURPOSE OF REVIEW

Recently there has been growing interest in non-IgE-mediated and irritant-induced occupational rhinitis due to old and new low-molecular-weight and irritant agents. The purpose of this review is to summarize the scientific evidence on agents and work activities responsible for non-IgE-mediated and irritant-induced occupational rhinitis and work-exacerbated rhinitis published in 2011 and 2012.

RECENT FINDINGS

Several epidemiological, surveillance and experimental studies, case reports and reviews showed that workers exposed to drugs, wood dust, chemicals, metals and biocides are at high risk of non-IgE-mediated and irritant-induced occupational rhinitis; among activities at risk are healthcare, antibiotic manufacturing and cleaning workers. Work-exacerbated rhinitis has not been specifically studied, but it is reasonable to expect that it is frequently associated with work-exacerbated asthma. Recently, work-related anosmia/microsmia, nasal polyps and sinusitis have also been described. Reducing or eliminating workplace exposure to the specific agent has been confirmed to be effective in preventing symptoms of nonallergic occupational rhinitis.

SUMMARY

In consideration of the relevance of non-IgE-mediated and irritant-induced work-related rhinitis, physicians should recognize work-related rhinitis symptoms due to old and new low-molecular-weight and irritant agents. The mechanisms of non-IgE-mediated and irritant-induced occupational rhinitis remain largely unclear and need to be studied further. Substitution of responsible agents, reduction or elimination of exposure at the workplace should be enforced as effective measures.