Effects of in utero and Postnatal Exposure to Secondhand Smoke on Lung Function by Gender and Asthma Status: The Seven Northeastern Cities (SNEC) Study

Abstract

Background: Little information exists on whether gender or asthma status modifies the effects of secondhand smoke (SHS) exposure on lung function. Objective: To evaluate whether gender or asthma status modifies the association of SHS exposure with lung function. Methods: A total of 6,740 children (average 11.6 years) were recruited from 24 districts of 7 cities in northeast China in 2012. SHS exposure included exposure to environmental and maternal smoking both in utero and during early childhood (postnatal). Lung function was measured using electronic spirometers. Two-step regressions were used to analyze the association between SHS and lung function. Results: In utero and postnatal exposure to SHS was independently associated with decreased lung function in both genders; however, this association was greater among males. For example, when exposed to maternal smoking during pregnancy, the adjusted odds ratio (aOR) for decreased forced vital capacity (FVC) was 6.46 (95% confidence interval [CI]: 2.58-16.17) among males, while only 2.16 (95% CI: 0.96-4.88) among females. More positive associations between SHS exposure and decreased lung function were detected among nonasthmatic compared with asthmatic children. Nonasthmatics had significantly larger deficits from in utero exposure to maternal smoking, which concerned decreased lung FVC function (aOR = 2.58, 95% CI: 1.28-5.21) and decreased lung forced expiratory volume in 1 s (FEV1) function (aOR = 2.32, 95% CI: 1.01-5.33). A similar pattern was also observed for the associations between SHS exposure and continuous pulmonary function test measurements. Conclusions: SHS exposure was associated with decreased lung function. Males and nonasthmatics seem to be more susceptible than their respective counterparts.

Impact on lung function among children exposed to home new surface materials: The seven Northeastern Cities Study in China

“…The Seven Northeastern Cities (SNEC) study is a large population‐based cross‐sectional study, the details of which have been previously reported . Briefly, we selected seven cities in Liaoning Province of Northeastern China (Shenyang, Dalian, Anshan, Fushun, Benxi, Liaoyang, and Dandong) from April 2012 to June 2013.…”

“…Two study technicians measured lung function in children using electronic spirometers (Spirolab, MIR, Italy) as previously described in detail . Briefly, after 5 minutes of rest, spirometry was measured three times according to the American Thoracic Society (ATS) and European Respiratory Society (ERS) protocols, which are adjusted for body temperature and saturated pressure.…”

“…The spirometry instruments were calibrated before and after each examination as well as quality controlled. We captured continuous FEV1, FVC, MMEF, and PEF, and dichotomized values “impaired” according to FEV1 <85%, FVC <85%, PEF <75%, and MMEF <75% of the predicted value for Chinese children, which was previously shown to be well‐suited for research such as the present study . The details of this predicted value have been described in the Supporting Information.…”

“…We used two‐level logistic regression to calculate odds ratios (OR) with 95% confidence intervals (CI) for establishing the associations between home renovation and lung function impairment, and two‐level linear regression to calculate the change in continuous spirometric parameters in association with home renovation. The details of this model have been described elsewhere and detailed in the Supporting Information.…”

“…The Seven Northeastern Cities (SNEC) study is a large population-based cross-sectional study, the details of which have been previously reported. 12,13 Briefly, we selected seven cities in Liaoning Province of Northeastern China (Shenyang, Dalian, Anshan, Fushun, Benxi, Liaoyang, and Dandong) from April 2012 to June 2013. There are three districts in Anshan, Benxi, and Dandong, four districts in Dalian and Fushun, two districts in Liaoyang, and five districts in Shenyang.…”