Effects of air pollution on respiratory health of adults in three Chinese cities

Prevalence of chronic cough in China: a systematic review and meta-analysis

Background

Individual studies have indicated variable prevalence for chronic cough, but thus far, there has been no systematic report on the prevalence of this condition.

Methods

In this study, we performed a systematic review and meta-analysis by searching databases including PubMed, Cochrane Library, Web of Science, China National Knowledge Infrastructure, Chinese biomedical literature service system, Wanfang Database, and VIP database, for studies on chronic cough in China published before December 28, 2020. A random effects model was used to calculate pooled prevalence estimates with 95% confidence interval [95%CI], weighted by study size.

Results

Fifteen studies with 141,114 community-based adults were included in the study, showing a prevalence of 6.22% (95% CI 5.03–7.41%). And 21 studies with 164,280 community-based children were included, presenting a prevalence of 7.67% (95% CI 6.24–9.11%). In subgroup meta-analyses, the prevalence in adults was 4.38% (95% CI 2.74–6.02%) in southern China and 8.70% (95% CI 6.52–10.88%) in northern China. In the children population, the prevalence in northern China was also higher than in southern China (northern vs. southern: 7.45% with a 95% CI of 5.50–9.41%, vs. 7.86% with a 95% CI of 5.56–10.16%).

Conclusions

Our population-based study provides relatively reliable data on the prevalence of chronic cough in China and may help the development of global strategies for chronic cough management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01847-w.

Changes in children's respiratory morbidity and residential exposure factors over 25 years in Chongqing, China

Background

Respiratory morbidity and mortality during childhood remains a major challenge for global health. Due to the rapid economic development in Chongqing, we expect substantial temporal changes in respiratory health status and environmental risk factors in children. By leveraging a historical dataset, this study aims to assess the changes in prevalence of respiratory symptoms and diseases, residential exposure factors, and their associations in school-age children over a period of 25 years.

Methods

This study involved two cross-sectional surveys conducted in Chongqing with a 25-year interval (2017 vs. 1993). Purpose sampling was used to conduct questionnaire surveys on school-age children in both surveys. Information collected include children’s respiratory health outcomes, family residential exposures, demographic information, and parental respiratory disease history. The changes of residential exposures as well as demographics were determined by chi-square test. Odds ratios were calculated to compare the prevalence of children’s respiratory symptoms and diseases between the two periods. Associations between children’s respiratory outcomes and exposure indicators were assessed using multivariate logistic regressions.

Results

The majority of residential exposure indicators improved in 2017, including sleep in shared room, cooking with coal, poor kitchen ventilation, cooking frequency, and parental smoking. Compared to the 1993 study, the adjusted risk for children’s wheezing was lower (OR: 0.38, 95% CI: 0.29, 0.49), but the risk for bronchitis was higher (OR: 1.89, 95% CI: 1.54, 2.31) in the 2017 study. Poor kitchen ventilation and parental smoking were linked to an increased risk of children’s wheezing (OR: 1.39, 95% CI: 1.02, 1.90) and bronchitis (OR: 1.51, 95% CI: 1.02, 2.21), respectively, while heating in winter was linked to an increased risk of phlegm (OR: 1.40, 95% CI: 1.03, 1.90) and wheezing (OR: 1.47, 95% CI: 1.07, 2.01) in the 1993 study. However, these residential exposure factors were no longer associated with the children’s respiratory diseases in the 2017 study.

Conclusions

Our study found improvement of residential exposures in Chongqing, a decline of prevalence of children’s wheezing but an increase of that of bronchitis from 1993 to 2017. Poor kitchen ventilation, heating in winter, and parental smoking were significant risk factors in the 1993 survey but, with significantly reduced prevalence in 2017, were not significantly associated with children’s respiratory morbidity in the latter survey.

Does chronic disease influence susceptibility to the effects of air pollution on depressive symptoms in China?

Background

Exogenous stressors resulting from air pollution can lead to depression and chronic disease. Chinese levels of air pollution are among the highest in the world, and although associated adverse health effects are gradually emerging, research determining individual vulnerability is limited. This study estimated the association between air pollution and depressive symptoms and identified whether chronic disease influences an individual’s susceptibility to depressive symptoms relating to air pollution.

Methods

Individual sample data from the China Health and Retirement Longitudinal Study and a group of city-level variables in 2011 and 2013 were used with the random effects model and Tobit model. Adjustments were made for demographic, socioeconomic status, health behavior, and city-level climate variables with respect to living areas. Analysis was also stratified using chronic disease characteristics.

Results

The total Center for Epidemiological Studies Depression scale evaluating depressive symptoms ranged between 7 and 28 [average 11.623 (SD = 4.664)]. An 1% increase in sulfur dioxide and total suspended particulate emission intensities was associated with depressive symptoms scores that were 1.266 (SE = 0.107, P < 0.001, 95% CI 1.057–1.475) and 1.318 (SE = 0.082, P < 0.001, 95% CI 1.157–1.480) higher, respectively. Compared to respondents without chronic disease, those with chronic diseases such as hypertension, dyslipidemia, diabetes or high blood sugar, cardiovascular diseases, cancer or malignant tumor, liver disease, chronic lung diseases, kidney disease, stomach or other digestive disease, arthritis or rheumatism, and asthma had scores that were higher for depressive symptoms.

Conclusions

Results confirm that the adverse health effects of air pollution should be considered when developing air pollution policies. Findings also provide justification for mental health interventions targeting air pollution exposure, especially for people with chronic diseases.

Effect of indoor air pollution from biomass and solid fuel combustion on prevalence of self-reported asthma among adult men and women in India: findings from a nationwide large-scale cross-sectional survey

OBJECTIVES

Increasing prevalence of asthma in developing countries has been a significant challenge for public health in recent decades. A number of studies have suggested that ambient air pollution can trigger asthma attacks. Biomass and solid fuels are a major source of indoor air pollution, but in developing countries the health effects of indoor air pollution are poorly understood. In this study we examined the effect of cooking smoke produced by biomass and solid fuel combustion on the reported prevalence of asthma among adult men and women in India.

METHODS

The analysis is based on 99,574 women and 56,742 men aged between 20 and 49 years included in India's third National Family Health Survey conducted in 2005-2006. Effects of exposure to cooking smoke, determined by the type of fuel used for cooking such as biomass and solid fuels versus cleaner fuels, on the reported prevalence of asthma were estimated using multivariate logistic regression. Since the effects of cooking smoke are likely to be confounded with effects of tobacco smoking, age, and other such factors, the analysis was carried out after statistically controlling for such factors.

RESULTS

The results indicate that adult women living in households using biomass and solid fuels have a significantly higher risk of asthma than those living in households using cleaner fuels (OR: 1.26; 95%CI: 1.06-1.49; p = .010), even after controlling for the effects of a number of potentially confounding factors. Interestingly, this effect was not found among men (OR: 0.98; 95%CI: 0.77-1.24; p = .846). However, tobacco smoking was associated with higher asthma prevalence among both women (OR: 1.72; 95%CI: 1.34-2.21; p < .0001) and men (OR: 1.35; 95%CI: 1.49-2.25; p < .0001). Combined effects of biomass and solid fuel use and tobacco smoke on the risk of asthma were greater and more significant in women (OR: 2.16; 95%CI: 1.58-2.94; p < .0001) than they were in men (OR: 1.34; 95%CI: 1.04-1.72; p = .024).

CONCLUSIONS

The findings have important program and policy implications for countries such as India, where large proportions of the population still rely on polluting biomass fuels for cooking and heating. Decreasing household biomass and solid fuel use and increasing use of improved stove technology may decrease the health effects of indoor air pollution. More epidemiological research with better measures of smoke exposure and clinical measures of asthma is needed to validate the findings.

Indoor air pollution and lung function growth among children in four Chinese cities

Ambient air pollution has been associated with decreased growth in lung function among children; but little is known about the impact of indoor air pollution. We examined relationships between indoor air pollution metrics and lung function growth, among children (n = 3273) aged 6-13 years living in four Chinese cities. Lung function parameters (FVC and FEV(1) ) were measured twice a year. Questionnaires were used to determine home coal burning and ventilation practices. Generalized estimating equations were used to examine associations. Use of coal as a household fuel was associated with 16.5 ml/year lower (33%, P < 0.001) and 20.5 ml/year lower (39%, P < 0.001) growth in children's FEV(1) and FVC, respectively. FEV(1) growth was 10.2 ml/year higher (20%, P = 0.009), and FVC growth was 17.0 ml/year higher (33%, P < 0.001) among children who lived in houses with the presence of a ventilation device. Among children living in houses where coal was used as a fuel and no ventilation devices were present, adjusted FVC and FEV(1) growth, respectively, were 37% and 61% that of the average growth per year in the full cohort. This suggests that household coal use may cause deficits in lung function growth, while using ventilation devices may be protective of lung development.

PRACTICAL IMPLICATIONS

Nearly 3.4 billion people use solid fuels in homes for cooking and/or heating. We report the following findings from a longitudinal study: (i) household coal use is significantly associated with reduction in children's lung function growth and (ii) the use of household ventilation devices is significantly associated with higher lung function growth, particularly among children living in households where coal is used as a fuel. These findings not only provide evidence that indoor coal use impairs children's lung development but also point to the importance of improving ventilation conditions in reducing harmful effects of indoor air pollution sources.

Respiratory symptoms among residents of a heavy-industry province in China: prevalence and risk factors

OBJECTIVE

In China, significant levels of environmental pollution, substandard worksite quality and high rates of smoking predispose the population to potentially high risks of respiratory illnesses and other diseases. We assessed the prevalence of respiratory symptoms and their risks in relation to personal, occupational and environmental risk factors in a heavy-industry province of northeastern China.

METHODS

Lifestyle, health, residential and occupational data were obtained in 2002 from 31,704 adults of six cities in Liaoning, China, using self-assessment questionnaires. General linear and multi-level models were used to evaluate prevalence rates and risks of respiratory symptoms, related to both individual and combined exposures to environmental and occupational risk factors.

RESULTS

The crude prevalence rates (PRs) for persistent cough, persistent phlegm, wheeze and asthma were 2.3, 3.8, 2.1 and 1.0%, respectively. The odds ratios (ORs) of all four respiratory symptoms examined were increased by: smoking (ORs from 2.06 to 5.02), occupational dust (ORs from 1.35 to 1.72), occupational gas (ORs from 1.48 to 1.72) and presence of irritating smoke during cooking (ORs from 1.54 to 2.22). An index combining proximity of residence to road, factory or chimney, indoor coal use and presence of irritating smoke during cooking was associated with up to 3.9-fold increased risks of all symptoms. Increasing values of each risk factor were generally associated with dose-response trends in prevalence rates and risks (all p for trend <0.01).

CONCLUSION

The crude PRs of symptoms were lower than those reported by European and American studies but closer to those of previous Chinese studies. The risks of respiratory symptoms in this population were increased by smoking, occupational exposures to dust and gas, and combined residence-related exposures such as living close to a main road, factory or chimney, indoor coal use and the presence of irritating smoke during cooking, among other risk factors.

Health benefit evaluation of the energy use scenarios in Beijing, China

Air pollution is one of the important causal factors for excess cardiorespiratory deaths and diseases. However, little information is available on health gains from clean energy usage in developing countries. In this study the expected population exposed to air pollutants was estimated under the different energy use scenarios by the year 2010, 2020 and 2030, respectively, in the urban area of Beijing, China. The concentration-response functions between air pollutants and the health endpoints were established using meta-analysis and regression models. The decreased cardiorespiratory deaths and diseases of the exposed population were predicted as the health benefits from air pollution reduction. We used daily measurements of particulate matter less than 10 mum in aerodynamic diameter (PM(10)) and sulphate dioxide (SO(2)) as air pollution indicators. The percentage of population exposed to higher level of PM(10) will be decreased significantly under the clean energy use scenario than that under the Baseline Scenario (i.e., business-as-usual scenario). Compared with the Baseline Scenario there will be, by 2010, 2020, and 2030, respectively, a decrease of 29-152, 30-212 and 39-287 acute excess deaths; and 340-1811, 356-2529 and 462-3424 chronic excess deaths associated with the reduction of PM(10) level; also a decrease of 237-331, 285-371 and 400-554 short-term excess deaths associated with the decrease of SO(2) level. Meanwhile, the number of respiratory and cardiovascular hospital admissions, outpatient visits to internal and paediatrics departments, total emergency room visits and asthma attacks will be remarkably reduced with the reduction of air pollution. Energy structure improvement could reduce ambient air pollution and produce substantial health benefits to the population in Beijing. These findings may have significant implications for other metropolitan cities, particularly in developing countries.

Valuing the adult health effects of air pollution in Chinese cities

China's ongoing economic growth is accompanied by a large amount of air pollution that exacts significant health and economic costs on its people. Following up on some earlier work focusing upon general mortality and child-specific health effects, this article uses a larger data set, covering more than 90 Chinese cities, along with a set of China-based epidemiological functions, to estimate some of the adult health benefits of reducing urban air pollution. Projecting future air pollution based upon current conditions, it calculates the averted mortality and morbidity effects that would result from the cleanup of particulates, sulfur dioxide, and nitrogen dioxide. The inclusion of nitrogen dioxide in our analysis is particularly important because it is a growing problem and has not been included in most of the more widely known studies that examine Chinese air pollution. Finally, the economic valuation of these pollution-related health effects is developed, using a number of recent, China-based valuation studies.

Exposure-response functions for health effects of ambient air pollution applicable for China -- a meta-analysis

Assessing the benefits of projects and policies to reduce air pollution requires quantitative knowledge about the relationship between exposure to air pollution and public health. This article proposes exposure-response functions for health effects of PM10 and SO2 pollution in China. The functions are based on Chinese epidemiological studies, and cover mortality, hospital admissions, and chronic respiratory symptoms and diseases. We derive the following coefficients for acute effects: a 0.03% (S.E. 0.01) and a 0.04% (S.E. 0.01) increase in all-cause mortality per microg/m3 PM10 and SO2, respectively, a 0.04% (S.E. 0.01) increase in cardiovascular deaths per microg/m3 for both PM10 and SO2, and a 0.06% (S.E. 0.02) and a 0.10% (S.E. 0.02) increase in respiratory deaths per microg/m3 PM10 and SO2, respectively. For hospital admissions due to cardiovascular diseases the obtained coefficients are 0.07% (S.E. 0.02) and 0.19% (S.E. 0.03) for PM10 and SO2, respectively, whereas the coefficients for hospital admissions due to respiratory diseases are 0.12% (S.E. 0.02) and 0.15% (S.E. 0.03) for PM10 and SO2, respectively. Exposure-response functions for the impact of long-term PM10 levels on the prevalence of chronic respiratory symptoms and diseases are derived from the results of cross-sectional questionnaire surveys, and indicate a 0.31% (S.E. 0.01) increase per microg/m3 in adults and 0.44% (S.E. 0.02) per microg/m3 in children. With some exceptions, Chinese studies report somewhat lower exposure-response coefficients as compared to studies in Europe and USA.

Association between traffic volume and health care use for asthma among residents at a U.S.-Canadian border crossing point

Little information is available about health impacts of the North American Free Trade Agreement (NAFTA) traffic-related pollution on residents near the major traffic corridors along the U.S.-Canadian border. Here we report on a 10 year (1991-2000) retrospective study of commercial traffic volumes across the Peace Bridge and health care use for asthma in a residential community, which serves as a conduit for traffic crossing between Fort Erie, Ontario, Canada, and Buffalo, New York. We hypothesized that commercial traffic pollution was impacting on residents in close proximity to the trade corridor. Commercial traffic volumes, hospital discharges for asthma, and outpatient visits to area hospitals and clinics were analyzed before and after implementation of NAFTA. Results showed a positive association between increased commercial traffic volume and increased health care use for asthma. Zip codes 14201 and 14213, which surround the Peace Bridge Plaza Complex (PBC), had the highest prevalence rates and health care use rates for asthma. Statistical analysis showed the findings to be significant (p < 0.05) in that residential proximity to the PBC was associated with greater hospital discharge rates for asthma. The findings were strongest (p < 0.000) in the zip codes where the PBC was located (14213) and the major highway I-190 passed through (14201). A yearly excess of 230.2 adult asthma hospital discharges was associated with an increase in traffic volume during the period from 1991 to 1996 in the study area. This is in contrast to an overall decrease in the national rate of hospitalizations for asthma by 7.5% in the same period. The results suggest that NAFTA-related commercial traffic has a negative health impact on asthmatics living in close proximity to the trade corridor. Health and social costs due to traffic pollution need to be included in cost estimates of transport decisions related to the NAFTA corridors. Similar health effects due to NAFTA traffic need to be studied at other U.S.-Canada border crossing points.

Using air pollution based community clusters to explore air pollution health effects in children

To study respiratory health effects of long-term exposure to ambient air pollutant mixture, we observed 7058 school children 5-16 years of age living in the four Chinese cities of Lanzhou, Chongqing, Wuhan, and Guangzhou. These children were enrolled from elementary schools located in eight districts, one urban district and one suburban district in each of the above cities. Ambient levels of PM(2.5), PM(10-2.5), total suspended particles (TSP), SO(2), and NO(x) were measured in these districts from 1993 to 1996. Based on a cluster analysis of arithmetic mean concentrations of PM(2.5), PM(10-2.5), (TSP-PM(10)), SO(2), and NO(x), we classified these children into four ordinal categories of exposure to ambient air pollutant mixtures. We tested for exposure-response relationships using logistic regression models, controlling for relevant covariates. We observed monotonic, positive relationships of exposure to the pollutant mixture with prevalence rates of cough with phlegm and wheeze. Other outcomes were not associated with the exposure in a monotonic exposure-response pattern. Even so, odds ratios for cough, phlegm, bronchitis, and asthma in the higher exposure district clusters were all higher than in the lowest exposure district cluster. We found evidence that exposure to the pollutant mixtures had adverse effects on children living in the four Chinese cities.

Exposure-response relationships between lifetime exposure to residential coal smoke and respiratory symptoms and illnesses in Chinese children

Data collected in a large epidemiologic study were analyzed to examine respiratory health effects of residential coal use in 7058 school children living in the four Chinese cities of Chongqing, Guangzhou, Lanzhou, and Wuhan. A Scenario Evaluation Approach was used to develop two exposure variables, heating coal smoke and cooking coal smoke. Estimated lifetime exposures to heating coal smoke and cooking coal smoke were both classified into four-level ordinal scales, as follows: no reported exposure (control); lightly exposed; moderately exposed; and heavily exposed. Zero-one dummy variables were constructed for each exposure level other than the control level (total six variables). These variables were entered into the analytical model. We tested for exposure-response relationships using logistic regression models, while controlling for other relevant covariates, including an indicator variable of ambient air pollution levels. We observed monotonic and positive exposure-response relationships of exposure to heating coal smoke with modeled odds ratios (ORs) of phlegm, cough with phlegm, and bronchitis. Other health outcomes were not associated with such exposure in a monotonic exposure-response pattern. However, ORs for cough, wheeze, and asthma were all higher in the exposed groups than in the control group. We observed no consistent associations between cooking coal smoke and the examined health outcomes. We conclude that exposure to heating coal smoke could have adverse effects on children's respiratory symptoms and illnesses in these four Chinese cities.