Respiratory effects of environmental tobacco exposure are enhanced by bronchial hyperreactivity

Secondhand smoke increases the risk of developing chronic obstructive pulmonary disease

Smoking is the most important risk factor for chronic obstructive pulmonary disease (COPD), however evidence from large-scale studies on whether secondhand smoke (SHS) increases the risk of COPD is still lacking. We conducted this large longitudinal study to investigate the association between SHS and the development of COPD. This is a longitudinal study. Data on 6519 subjects who were never-smokers, had no history of COPD, and had complete lung function records were extracted from the Taiwan Biobank. They were divided into two groups according to SHS exposure: no exposure and exposure groups. Data were collected when participants enrolled in the study and during regular follow-up. Cox proportional hazards regression models were used to estimate the relative risk (RR) and 95% confidence interval (CI) for the association between SHS and the risk of developing COPD. At 48 months of follow-up, 260 (4%) participants in the no exposure group and 34 (7%) participants in the exposure group developed COPD. The RR of incident COPD development was significantly higher in the exposure group than that in the no exposure group after adjusting for confounders (RR = 1.49; 95% CI 1.04 to 2.14; P value = 0.031). There is a dose-response relationship between the duration of exposure to SHS and the risk of incident COPD, which demonstrates that an additional hour of exposure to SHS per week was associated with a 1.03-fold increased likelihood of developing COPD after adjusting for confounders (RR = 1.03; 95% CI 1.00 to 1.05; P value = 0.027). SHS exposure contributes to the development of COPD. This finding can help raise awareness of the harms of SHS and provide a reference for formulating anti-smoking policies.

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

HRCT findings in secondhand smokers with respiratory symptoms

PURPOSE

The present study aims to investigate the occurrence and severity of HRCT abnormalities in symptomatic never-smokers, passively exposed to cigarette smoke.

MATERIALS AND METHODS

A total of 135 never-smokers with respiratory symptoms, without underlying lung disease, underwent paired inspiratory-expiratory HRCT and completed the secondhand smoking (SHS) exposure scale questionnaire. Individuals passively exposed to tobacco consisted the secondhand smoking group (SHS group) (n = 68); the remaining 67 controls were never exposed to SHS. Statistical analysis was performed using the Kolmogorov-Smirnov, x² and Pearson Point-Biserial correlation tests. P < 0.05 was statistically significant.

RESULTS

HRCT findings in SHS group included bronchial wall thickening (98.5%), mild cylindrical bronchiectasis (44%), ground-glass opacities (17.6%), and mosaic attenuation pattern (53%). Air trapping occurred in 65% of expiratory scans. Differences in occurrence of findings between SHS group participants and controls were statistically significant (p < 0.0001). There was significant correlation between exposure to tobacco smoke in hours/day and in number of cigarettes/day and the presence of mosaic attenuation pattern, ground-glass opacities, cylindrical bronchiectasis and air trapping, respectively (p < 0.05). Cumulative SHS exposure in years was also strongly correlated with the presence of ground-glass opacities, mosaic attenuation pattern, cylindrical bronchiectasis, and air trapping, as well as with the frequency of respiratory symptoms (p < 0.05).

CONCLUSION

HRCT findings attributed to SHS are mostly related to airway involvement and are correlated with the duration and grade of exposure to environmental tobacco smoke. SHS followed by lifestyle adjustments should be considered in symptomatic non-smokers with such HRCT findings.

Environmental tobacco smoke exposure and Chinese schoolchildren's respiratory health: a prospective cohort study

BACKGROUND

Although China is the most coveted cigarette market worldwide, few studies have examined the longitudinal effects of environmental tobacco smoke (ETS) on health.

PURPOSE

To examine the relationship between exposure to ETS and respiratory health in Chinese schoolchildren.

METHODS

The study subjects included 1718 children, who were never-smokers, aged 10.05±0.86 years and asthma-free at baseline. The children performed spirometric tests in 2006 and 18 months later. Parents reported the children's respiratory symptoms and illnesses, ETS exposure, and other related information by self-administered survey at both assessment points. The data were analyzed in 2010.

RESULTS

Significant exposure-response relationships were found between ETS exposure and coughing at night (p for trend<0.001); sneezing (p for trend=0.031); and sneezing with itchy, watery eyes (p for trend=0.006) in the first survey, and coughing at night (p for trend=0.019); phlegm without a cold (p for trend<0.001); and sneezing (p for trend=0.036) in the second survey. Compared with those who reported no ETS exposure in either survey, children who had a high ETS exposure level (>5 cigarettes/day) in either survey had lower growth rates in forced expiratory flow between 25% and 75% of forced vital capacity (FEF(25-75); β= -0.104, p=0.020) and forced expiratory flow at 25% of forced vital capacity (FEF(25); β= -0.077, p=0.027). A monotonic exposure-response effect was observed between ETS exposure and the deficits in the growth rate of FEF(25) and FEF(25-75.)

CONCLUSIONS

Exposure to ETS increased the risks of respiratory symptoms in Chinese school-aged children and was associated with impaired lung function growth. A dose-response relationship was observed for the latter effect.

Effect modification of immunoglobulin E-mediated atopy and rhinitis by glutathione S-transferase genotypes in passive smokers

BACKGROUND

Experimental studies suggest that glutathione S-transferase (GST) genotypes modify nasal allergen responses induced by secondhand smoke (SHS) exposure.

OBJECTIVE

We aimed to investigate whether GSTs affected systemic IgE and allergic rhinitis (AR) in SHS-exposed individuals from a population-based cohort.

METHODS

Analyses comprised 2309 never-smokers from the Swiss study on air pollution and health in adults cohort, reporting SHS status at baseline and 11 years later. Outcomes were defined by total serum IgE≥100 kU/L, specific serum IgE determined by Phadiatop® ≥0.35 kU/L and self-reported AR. GSTP1 Ile105Val, GSTM1 and GSTT1 gene deletion genotypes were identified at the follow-up survey.

RESULTS

After adjustment for relevant covariates, the homozygous GSTP1 105-Val genotype was negatively associated with high total IgE and high-specific IgE by Phadiatop®, notably in subjects persistently exposed to SHS (OR: 0.20, 95% CI 0.05-0.75; P=0.02, for high total IgE and OR: 0.29, 95% CI 0.10-0.89; P=0.03, for high specific IgE by Phadiatop®). Carrying at least one copy of the GSTM1 gene (non-null) showed a similar association for high specific IgE by Phadiatop® (OR: 0.41, 95% CI 0.22-0.76; P=0.004). No significant associations were found between GSTs and rhinitis.

CONCLUSION AND CLINICAL RELEVANCE

In this large cohort, homozygosity for GSTP1 105-Val or carrying the GSTM1 non-null genotype decreased the risk of high total IgE or high specific IgE using Phadiatop® by nearly half in subjects exposed to SHS, as compared with subjects carrying opposite alleles. These findings underline the value of genetic susceptibility when evaluating the effects of environmental exposure on allergic illness. The potential long-term effects of persistent SHS exposure in genetically vulnerable individuals may be of public health relevance.

Passive smoking and chronic obstructive pulmonary disease: cross-sectional analysis of data from the Health Survey for England

OBJECTIVES

There is increasing evidence that passive smoking is associated with chronic respiratory diseases, but its association with chronic obstructive pulmonary disease (COPD) requires more study. In this cross-sectional analysis of data from 3 years of the Health Survey for England, the association between passive smoking exposure and risk of COPD is evaluated.

DESIGN

Cross-sectional analysis of the 1995, 1996 and 2001 Health Surveys for England including participants of white ethnicity, aged 40+ years with valid lung function data. COPD was defined using the lower limit of normal spirometric criteria for airflow obstruction. Standardised questions elicited self-reported information on demography, smoking history, ethnicity, occupation, asthma and respiratory symptoms (dyspnoea, chronic cough, chronic phlegm, wheeze). Passive smoking was measured by self-report of hours of exposure to cigarette smoke per week.

RESULTS

Increasing passive smoke exposure was independently associated with increased risk of COPD, with adjusted OR 1.05 (95% CI 0.93 to 1.18) for 1-19 h and OR 1.18 (95% CI 1.01 to 1.39) for 20 or more hours of exposure per week. Similar patterns (although attenuated and non-significant) were observed among never smokers. More marked dose-response relationships were observed between passive smoking exposure and respiratory symptoms, but the most marked effects were on the development of clinically significant COPD (airflow obstruction plus symptoms), where the risk among never smokers was doubled (OR 1.98 (95% CI 1.03 to 3.79)) if exposure exceeded 20 h/week.

CONCLUSION

This analysis adds weight to the evidence suggesting an association between passive smoking exposure and COPD.

Tobacco smoke exposure and tracking of lung function into adult life

Maternal smoking during pregnancy leads to abnormal lung function in infancy that tracks through to later childhood and continues into adult life. This is associated with transient wheezing illnesses through early childhood. Both social and physiological factors are likely to predispose those exposed to passive smoke to become active smokers. Adult smokers demonstrate an increased decline of lung function with age. The effects of passive smoke exposure vary with genetic factors, gender, race and exposure to other pollutants. Exposure to environmental tobacco smoke and subsequent active smoking both aggravate symptoms and have a negative effect on lung function in those with asthma.

Passive smoking exposure and risk of COPD among adults in China: the Guangzhou Biobank Cohort Study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a leading cause of mortality in China, where the population is also exposed to high levels of passive smoking, yet little information exists on the effects of such exposure on COPD. We examined the relation between passive smoking and COPD and respiratory symptoms in an adult Chinese population.

METHODS

We used baseline data from the Guangzhou Biobank Cohort Study. Of 20 430 men and women over the age of 50 recruited in 2003-06, 15,379 never smokers (6497 with valid spirometry) were included in this cross-sectional analysis. We measured passive smoking exposure at home and work by two self-reported measures (density and duration of exposure). Diagnosis of COPD was based on spirometry and defined according to the GOLD guidelines.

FINDINGS

There was an association between risk of COPD and self-reported exposure to passive smoking at home and work (adjusted odds ratio 1.48, 95% CI 1.18-1.85 for high level exposure; equivalent to 40 h a week for more than 5 years). There were significant associations between reported respiratory symptoms and increasing passive smoking exposure (1.16, 1.07-1.25 for any symptom).

INTERPRETATION

Exposure to passive smoking is associated with an increased prevalence of COPD and respiratory symptoms. If this association is causal, we estimate that 1.9 million excess deaths from COPD among never smokers could be attributable to passive smoking in the current population in China. Our findings provide strong evidence for urgent measures against passive smoking in China.

Effects of passive smoking on heart rate variability, heart rate and blood pressure: an observational study

BACKGROUND

Exposure to environmental tobacco smoke (ETS) has been shown to increase the risk for cardiovascular diseases and death, and autonomic dysfunction (specifically, reduced heart rate variability (HRV)) is a predictor of increased cardiac risk. This study tests the hypothesis that ETS exposure reduces HRV in the general population and discusses possible pathways.

METHODS

This cross-sectional study was conducted between 2001 and 2003 and is part of the SAPALDIA (Swiss Cohort Study on Air Pollution and Lung Diseases in Adults) study. The analysis included 1218 randomly selected non-smokers aged 50 and above who participated in 24-h electrocardiogram recordings. Other examinations included an interview, investigating health status (especially respiratory and cardiovascular health and health relevant behaviours and exposure to ETS) and measurements of blood pressure, body height and weight.

RESULTS

Subjects exposed to ETS at home or at work for more than 2 h/day had a difference of -15% in total power (95%CI: -26 to -3%), low frequency power (-28 to -1%), low/high frequency ratio (-26 to -3%) and -18% (-29 to -4%) in ultralow frequency power of HRV compared with subjects not exposed to ETS at home or work. We also found a 2.7% (-0.01 to 5.34%) higher heart rate during the recording in exposed subjects.

CONCLUSIONS

Exposure to ETS at home and work is associated with lower HRV and with higher heart rate in an ageing population. Our findings suggest that exposure to ETS increases cardiac risk through disturbances in the autonomic nervous system.