Zhuohui Zhao

Asthmatic symptoms among pupils in relation to winter indoor and outdoor air pollution in schools in Taiyuan, China.

Background There are few studies on associations between children’s respiratory heath and air pollution in schools in China. The industrial development and increased traffic may affect the indoor exposure to air pollutants in school environment. Moreover, there is a need to study respiratory effects of environmental tobacco smoke (ETS) and emissions from new building materials in homes in China. Objectives We studied the associations between pupils’ asthmatic symptoms and indoor and outdoor air pollution in schools, as well as selected home exposures, in a coal-burning city in north China. Methods A questionnaire survey was administered to pupils (11–15 years of age) in 10 schools in urban Taiyuan, collecting data on respiratory health and selected home environmental factors. Indoor and outdoor school air pollutants and climate factors were measured in winter. Results A total of 1,993 pupils (90.2%) participated; 1.8% had cumulative asthma, 8.4% wheezing, 29.8% had daytime attacks of breathlessness. The indoor average concentrations of sulfur dioxide, nitrogen dioxide, ozone, and formaldehyde by class were 264.8, 39.4, 10.1, and 2.3 μg/m3, respectively. Outdoor levels were two to three times higher. Controlling for possible confounders, either wheeze or daytime or nocturnal attacks of breathlessness were positively associated with SO2, NO2, or formaldehyde. In addition, ETS and new furniture at home were risk factors for wheeze, daytime breathlessness, and respiratory infections. Conclusions Indoor chemical air pollutants of mainly outdoor origin could be risk factors for pupils’ respiratory symptoms at school, and home exposure to ETS and chemical emissions from new furniture could affect pupils’ respiratory health.

Asthmatic symptoms among pupils in relation to microbial dust exposure in schools in Taiyuan, China

Microbial exposure has been indicated as significant in the development of asthma and allergy among children. The aim of the study was to test whether microbial exposure and allergens in the school environment are associated with asthmatic symptoms in pupils. Data on asthmatic symptoms and respiratory infections were collected through a questionnaire survey among 1993 pupils aged 11–15 yr in 10 randomly selected schools in Taiyuan, China. Settled dust in classrooms was analysed using tandem gas chromatography‐mass spectrometry for 3‐hydroxy fatty acids, marker of lipopolysaccharide (LPS) from endotoxin, muramic acid (MuA), marker of bacteria and ergosterol (Erg) for fungi, quantifying both culturable and non‐culturable microbes. A total of 29.8% reported daytime attacks of breathlessness, 8.4% wheeze and 1.2% had doctor’s diagnosed asthma. Generally, MuA was negatively associated with wheeze and daytime attacks of breathlessness, the latter of which was negatively associated with Erg to a weaker extent. Total concentration of LPS was positively associated with daytime attacks of breathlessness, but shorter lengths of LPS, C10, C12 and C14 LPS were negatively associated with either wheezing or daytime attacks of breathlessness. For MuA and C10 and C12 of LPS, the associations were independent of airborne allergens and classroom crowdedness, and even independent of the other two microbial markers for MuA. Microbial exposure indicated by certain chemical markers (e.g. MuA) could be protective for asthmatic symptoms, but for LPS (endotoxin), the picture is more complex, varying by different lengths of fatty acids of LPS.

Acute Effect of Ambient Air Pollution on Stroke Mortality in the China Air Pollution and Health Effects Study

Background and Purpose— There have been no multicity studies on the acute effects of air pollution on stroke mortality in China. This study was undertaken to examine the associations between daily stroke mortality and outdoor air pollution (particulate matter <10 &mgr;m in aerodynamic diameter, sulfur dioxide, and nitrogen dioxide) in 8 Chinese cities. Methods— We used Poisson regression models with natural spline-smoothing functions to adjust for long-term and seasonal trends, as well as other time-varying covariates. We applied 2-stage Bayesian hierarchical statistical models to estimate city-specific and national average associations of air pollution with daily stroke mortality. Results— Air pollution was associated with daily stroke mortality in 8 Chinese cities. In the combined analysis, an increase of 10 &mgr;g/m3 of 2-day moving average concentrations of particulate matter <10 &mgr;m in aerodynamic diameter, sulfur dioxide, and nitrogen dioxide corresponded to 0.54% (95% posterior intervals, 0.28–0.81), 0.88% (95% posterior intervals, 0.54–1.22), and 1.47% (95% posterior intervals, 0.88–2.06) increase of stroke mortality, respectively. The concentration–response curves indicated linear nonthreshold associations between air pollution and risk of stroke mortality. Conclusions— To our knowledge, this is the first multicity study in China, or even in other developing countries, to report the acute effect of air pollution on stroke mortality. Our results contribute to very limited data on the effect of air pollution on stroke for high-exposure settings typical in developing countries.

Cardiopulmonary benefits of reducing indoor particles of outdoor origin: a randomized, double-blind crossover trial of air purifiers.

BACKGROUND Indoor exposure to fine particulate matter (PM2.5) from outdoor sources is a major health concern, especially in highly polluted developing countries such as China. Few studies have evaluated the effectiveness of indoor air purification on the improvement of cardiopulmonary health in these areas. OBJECTIVES This study sought to evaluate whether a short-term indoor air purifier intervention improves cardiopulmonary health. METHODS We conducted a randomized, double-blind crossover trial among 35 healthy college students in Shanghai, China, in 2014. These students lived in dormitories that were randomized into 2 groups and alternated the use of true or sham air purifiers for 48 h with a 2-week washout interval. We measured 14 circulating biomarkers of inflammation, coagulation, and vasoconstriction; lung function; blood pressure (BP); and fractional exhaled nitric. We applied linear mixed-effect models to evaluate the effect of the intervention on health outcome variables. RESULTS On average, air purification resulted in a 57% reduction in PM2.5 concentration, from 96.2 to 41.3 μg/m3, within hours of operation. Air purification was significantly associated with decreases in geometric means of several circulating inflammatory and thrombogenic biomarkers, including 17.5% in monocyte chemoattractant protein-1, 68.1% in interleukin-1β, 32.8% in myeloperoxidase, and 64.9% in soluble CD40 ligand. Furthermore, systolic BP, diastolic BP, and fractional exhaled nitrous oxide were significantly decreased by 2.7%, 4.8%, and 17.0% in geometric mean, respectively. The impacts on lung function and vasoconstriction biomarkers were beneficial but not statistically significant. CONCLUSIONS This intervention study demonstrated clear cardiopulmonary benefits of indoor air purification among young, healthy adults in a Chinese city with severe ambient particulate air pollution. (Intervention Study on the Health Impact of Air Filters in Chinese Adults; NCT02239744).

Fine Particulate Air Pollution and Daily Mortality. A Nationwide Analysis in 272 Chinese Cities

Rationale: Evidence concerning the acute health effects of air pollution caused by fine particulate matter (PM2.5) in developing countries is quite limited. Objectives: To evaluate short‐term associations between PM2.5 and daily cause‐specific mortality in China. Methods: A nationwide time‐series analysis was performed in 272 representative Chinese cities from 2013 to 2015. Two‐stage Bayesian hierarchical models were applied to estimate regional‐ and national‐average associations between PM2.5 concentrations and daily cause‐specific mortality. City‐specific effects of PM2.5 were estimated using the overdispersed generalized additive models after adjusting for time trends, day of the week, and weather conditions. Exposure‐response relationship curves and potential effect modifiers were also evaluated. Measurements and Main Results: The average of annual mean PM2.5 concentration in each city was 56 &mgr;g/m3 (minimum, 18 &mgr;g/m3; maximum, 127 &mgr;g/m3). Each 10‐&mgr;g/m3 increase in 2‐day moving average of PM2.5 concentrations was significantly associated with increments in mortality of 0.22% from total nonaccidental causes, 0.27% from cardiovascular diseases, 0.39% from hypertension, 0.30% from coronary heart diseases, 0.23% from stroke, 0.29% from respiratory diseases, and 0.38% from chronic obstructive pulmonary disease. There was a leveling off in the exposure‐response curves at high concentrations in most, but not all, regions. The associations were stronger in cities with lower PM2.5 levels or higher temperatures, and in subpopulations with elder age or less education. Conclusions: This nationwide investigation provided robust evidence of the associations between short‐term exposure to PM2.5 and increased mortality from various cardiopulmonary diseases in China. The magnitude of associations was lower than those reported in Europe and North America.

Heavy Smog and Hospital Visits in Beijing, China

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The prevalence and incidence of sick building syndrome in Chinese pupils in relation to the school environment: a two-year follow-up study.

UNLABELLED There are few incidence studies on sick building syndrome (SBS). We studied two-year change of SBS in Chinese pupils in relation to parental asthma/allergy (heredity), own atopy, classroom temperature, relative humidity (RH), absolute humidity (AH), crowdedness, CO₂, NO₂, and SO₂. A total of 1993 participated at baseline, and 1143 stayed in the same classrooms after two years. The prevalence of mucosal and general symptoms was 33% and 28% at baseline and increased during follow-up (P < 0.001). Twenty-seven percent reported at least one symptom improved when away from school. Heredity and own atopy were predictors of SBS at baseline and incidence of SBS. At baseline, SO₂ was associated with general symptoms (OR=1.10 per 100 μg/m³), mucosal symptoms (OR=1.12 per 100 μg/m³), and skin symptoms (OR=1.16 per 100 μg/m³). NO₂ was associated with mucosal symptoms (OR=1.13 per 10 μg/m³), and symptoms improved when away from school (OR=1.13 per 10 μg/m³). Temperature, RH, AH, and CO₂ were negatively associated with prevalence of SBS. Incidence or remission of SBS was not related to any exposure, except a negative association between SO₂ and new skin symptoms. In conclusion, heredity and atopy are related to incidence and prevalence of SBS, but the role of the measured exposures for SBS is more unclear. PRACTICAL IMPLICATIONS We found high levels of CO₂ indicating inadequate ventilation and high levels of SO₂ and NO₂, both indoors and outdoors. All schools had natural ventilation, only. Relying on window opening as a tool for ventilation in China is difficult because increased ventilation will decrease the level of CO₂ but increase the level of NO₂ and SO₂ indoors. Prevalence studies of sick building syndrome (SBS) might not be conclusive for causal relationships, and more longitudinal studies on SBS are needed both in China and other parts of the world. The concept of mechanical ventilation and air filtration should be introduced in the schools, and when planning new schools, locations close to heavily trafficked roads should be avoided.

Size-fractionated particulate air pollution and circulating biomarkers of inflammation, coagulation, and vasoconstriction in a panel of young adults.

Background: Short-term associations between size-fractionated particulate air pollution and circulating biomarkers are not well established, especially in developing countries with high levels of particulate matter (PM). Methods: We designed a panel study involving 34 healthy young adults to evaluate acute effects of size-fractionated PM on 13 circulating biomarkers of inflammation, coagulation, and vasoconstriction. We measured real-time, size-fractionated number concentrations of PM (aerodynamic diameters from 0.25 to 10 &mgr;m, mass concentrations of PM < 10 &mgr;m) over four follow-up measurements. The short-term associations between size-fractionated PM and biomarkers were assessed using linear mixed effect models. Results: We found positive associations between short-term exposure to PM and 10 biomarkers. PM with smaller size had stronger associations. The size fractions with the strongest associations were 0.25–0.40 &mgr;m for number concentrations and <1 &mgr;m for mass concentrations. For example, an interquartile range increase in 24-hour-average number concentrations of PM0.25–0.40 was associated with a 7%–32% increase in biomarkers of inflammation, 34%–68% of blood coagulation, and 45% of vasoconstriction. Similar estimates were found for mass concentrations of PM1. Furthermore, our results demonstrated an apparent acute effect on circulating biomarkers, even 2 hours after exposure. The effects were strongest within the first 12–24 hours, and effects on inflammation occurred more quickly than on coagulation and vasoconstriction. Conclusions: Our results provided potentially vital insights into the size and temporal characteristics of PM that could modify subclinical cardiovascular effects. These findings may have implications on disease prevention and environmental regulation in China.

Particulate Matter Exposure and Stress Hormone Levels: A Randomized, Double-Blind, Crossover Trial of Air Purification

Background: Exposure to ambient particulate matter (PM) is associated with a number of adverse health outcomes, but potential mechanisms are largely unknown. Metabolomics represents a powerful approach to study global metabolic changes in response to environmental exposures. We therefore conducted this study to investigate changes in serum metabolites in response to the reduction of PM exposure among healthy college students. Methods: We conducted a randomized, double-blind crossover trial in 55 healthy college students in Shanghai, China. Real and sham air purifiers were placed in participants’ dormitories in random order for 9 days with a 12-day washout period. Serum metabolites were quantified by using gas chromatography-mass spectrometry and ultrahigh performance liquid chromatography-mass spectrometry. Between-treatment differences in metabolites were examined using orthogonal partial least square-discriminant analysis and mixed-effect models. Secondary outcomes include blood pressure, corticotropin-releasing hormone, adrenocorticotropic hormone, insulin resistance, and biomarkers of oxidative stress and inflammation. Results: The average personal exposure to PMs with aerodynamic diameters ⩽2.5 &mgr;m was 24.3 &mgr;g/m3 during the real purification and 53.1 &mgr;g/m3 during the sham purification. Metabolomics analysis showed that higher exposure to PMs with aerodynamic diameters ⩽2.5 &mgr;m led to significant increases in cortisol, cortisone, epinephrine, and norepinephrine. Between-treatment differences were also observed for glucose, amino acids, fatty acids, and lipids. We found significantly higher blood pressure, hormones, insulin resistance, and biomarkers of oxidative stress and inflammation among individuals exposed to higher PMs with aerodynamic diameters ⩽2.5 &mgr;m. Conclusions: This study suggests that higher PM may induce metabolic alterations that are consistent with activations of the hypothalamus-pituitary-adrenal and sympathetic-adrenal-medullary axes, adding potential mechanistic insights into the adverse health outcomes associated with PM. Furthermore, our study demonstrated short-term reductions in stress hormone following indoor air purification. Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02712333.

Updated Prevalences of Asthma, Allergy, and Airway Symptoms, and a Systematic Review of Trends over Time for Childhood Asthma in Shanghai, China

Background The prevalence of asthma among Shanghai children has increased over time. This increase might be associated with changes in environmental exposures. Investigation of the time-trend of asthma and current prevalences is essential to understanding the causes. Objective To estimate the current prevalences of asthma, allergies and other respiratory symptoms among Shanghai preschool children, and to investigate the time-trend of childhood asthma prevalence of from 1990 to 2011. Methods From April 2011 to April 2012, the CCHH (China, Children, Homes, Health) cross-sectional study was conducted in Shanghai. Questionnaires were distributed to 17,898 parents or guardians of preschool children from 72 kindergartens in 5 districts. Previous similar studies were also summarized by a systematic literature review. Results From a total of 14,884 questionnaires for 3–7 year old children, prevalences of the following diseases and symptoms were calculated: asthma 10.2%, wheeze (ever) 28.1%, pneumonia (ever) 33.5%, otitis media 11.0%, rhinitis (ever) 54.1%, hay fever 12.2%, eczema (ever) 22.7%, and food allergy 15.7%. Urban children had higher prevalences of most symptoms than suburban children. The prevalence of asthma has increased significantly, almost five-fold, from 2.1% in 1990 to 10.2% in the present study. The prevalence of asthma in boys was higher than in girls in the present study and in all reviewed studies. Conclusions Asthma, allergy and airway symptoms are common among preschool children in Shanghai. The prevalence of childhood asthma in Shanghai has increased rapidly from 1990 to 2011.