Yue Leon Guo

Effects of particulate air pollution and ozone on lung function in non-asthmatic children.

INTRODUCTION Information on the long-term effects of different air pollutant levels on lung function is relatively lacking in Asia and still inconclusive in the world. Age differential effects of air pollution are not known. OBJECTIVES To assess the acute and subchronic effects of ambient air pollution on lung function and compared among children of different ages. METHODS From April to May 2011, a nationwide study was conducted on schoolchildren aged 6-15 years in 44 schools of 24 districts in Taiwan. Spirograms were obtained from 1494 non-asthmatic children. Air pollution data were retrieved from air monitoring stations within one kilometre of the schools. Using three-level hierarchical linear models, individual lung function was fitted to air pollution, with adjustments for demographics, indoor exposures, outdoor activity, and districts. RESULTS Lung function changes per inter-quartile increase of the past two-months average levels of particulate matter <2.5 μm (PM2.5) and ozone (12 μg/m(3), 32-44 and 6.7 ppb, 32-38, respectively) were -103 and -142 ml on FVC, -86 and -131 on FEV1, and -102 and -188 ml/s on MMEF, respectively. Lag-1-day ozone exposure was associated with decreased MMEF. In children aged 6-10, PM2.5 was associated with decreased FEV1/FVC and MMEF/FVC ratios. CONCLUSIONS In children aged 6-15 years, sub-chronic exposure to ambient PM2.5 and ozone leads to reduced lung capacity, whereas acute exposure to ozone decreases mid-expiratory flow. In children aged 6-10 years, additional airway obstructive patterns in lung function may be associated with PM2.5 exposure.

Ozone and Daily Mortality Rate in 21 Cities of East Asia: How Does Season Modify the Association?

Previous studies in East Asia have revealed that the short-term associations between tropospheric ozone and daily mortality rate were strongest in winter, which is opposite to the findings in North America and Western Europe. Therefore, we investigated the season-varying association between ozone and daily mortality rate in 21 cities of East Asia from 1979 to 2010. Time-series Poisson regression models were used to analyze the association between ozone and daily nonaccidental mortality rate in each city, testing for different temperature lags. The best-fitting model was obtained after adjustment for temperature in the previous 2 weeks. Bayesian hierarchical models were applied to pool the city-specific estimates. An interquartile-range increase of the moving average concentrations of same-day and previous-day ozone was associated with an increase of 1.44% (95% posterior interval (PI): 1.08%, 1.80%) in daily total mortality rate after adjustment for temperature in the previous 2 weeks. The corresponding increases were 0.62% (95% PI: 0.08%, 1.16%) in winter, 1.46% (95% PI: 0.89%, 2.03%) in spring, 1.60% (95% PI: 1.03%, 2.17%) in summer, and 1.12% (95% PI: 0.73%, 1.51%) in fall. We found significant associations between short-term exposure to ozone and higher mortality rate in East Asia that varied considerably from season to season with a significant trough in winter.

Projections of temperature-related excess mortality under climate change scenarios

Summary Background Climate change can directly affect human health by varying exposure to non-optimal outdoor temperature. However, evidence on this direct impact at a global scale is limited, mainly due to issues in modelling and projecting complex and highly heterogeneous epidemiological relationships across different populations and climates. Methods We collected observed daily time series of mean temperature and mortality counts for all causes or non-external causes only, in periods ranging from Jan 1, 1984, to Dec 31, 2015, from various locations across the globe through the Multi-Country Multi-City Collaborative Research Network. We estimated temperature–mortality relationships through a two-stage time series design. We generated current and future daily mean temperature series under four scenarios of climate change, determined by varying trajectories of greenhouse gas emissions, using five general circulation models. We projected excess mortality for cold and heat and their net change in 1990–2099 under each scenario of climate change, assuming no adaptation or population changes. Findings Our dataset comprised 451 locations in 23 countries across nine regions of the world, including 85 879 895 deaths. Results indicate, on average, a net increase in temperature-related excess mortality under high-emission scenarios, although with important geographical differences. In temperate areas such as northern Europe, east Asia, and Australia, the less intense warming and large decrease in cold-related excess would induce a null or marginally negative net effect, with the net change in 2090–99 compared with 2010–19 ranging from −1·2% (empirical 95% CI −3·6 to 1·4) in Australia to −0·1% (−2·1 to 1·6) in east Asia under the highest emission scenario, although the decreasing trends would reverse during the course of the century. Conversely, warmer regions, such as the central and southern parts of America or Europe, and especially southeast Asia, would experience a sharp surge in heat-related impacts and extremely large net increases, with the net change at the end of the century ranging from 3·0% (−3·0 to 9·3) in Central America to 12·7% (−4·7 to 28·1) in southeast Asia under the highest emission scenario. Most of the health effects directly due to temperature increase could be avoided under scenarios involving mitigation strategies to limit emissions and further warming of the planet. Interpretation This study shows the negative health impacts of climate change that, under high-emission scenarios, would disproportionately affect warmer and poorer regions of the world. Comparison with lower emission scenarios emphasises the importance of mitigation policies for limiting global warming and reducing the associated health risks. Funding UK Medical Research Council.

The Association of Ambient Air Pollution With Airway Inflammation in Schoolchildren

The biologic mechanisms involved in airway inflammatory response to air pollution are not clearly understood. The authors conducted a longitudinal study to investigate whether exposure to ambient air pollutants affected inflammatory cells and mediators from nasal lavage in schoolchildren. Study participants were 100 elementary and middle-school students in New Taipei City, Taiwan. A structured respiratory health questionnaire was administered in September 2007, followed by monthly measurement of nasal inflammation from October 2007 to November 2009. During the study period, daily concentrations of air pollutants were obtained from the Environmental Protection Administration monitoring station and the Aerosol Supersite. Mixed-effects models were applied to examine the association between air pollution and nasal inflammatory cells and mediators, including percentages of neutrophils, eosinophils, and monocytes in lavaged cells and interleukin-8. A total of 824 measurements were obtained from 100 participants over a period of 10 months. The level of particulate matter with an aerodynamic diameter of 2.5 μm or less (PM(2.5)) was found to be associated with percentage of neutrophils (β = 3.45%, 95% confidence interval: 0.89, 6.01) and interleukin-8 level (β = 29.98 pg/mL, 95% confidence interval: 3.26, 56.69) in the nasal lavage on the day of exposure. In this longitudinal cohort study of schoolchildren, results indicated that exposure to PM(2.5) might induce nasal inflammation.

Genetic susceptibility to dioxin-like chemicals’ induction of cytochrome P4501A2 in the human adult linked to specific AhRR polymorphism

BACKGROUND Dioxin-like chemicals are known to exert their effect by binding to aryl hydrocarbon receptor (AhR), forming complexes with aryl hydrocarbon nuclear translocator (ARNT), and binding to dioxin responsive elements (DREs) in promoter region to regulate the transcription of specific genes. In a previous study of the Yucheng cohort of humans who were exposed to high toxic levels of dioxin-like chemicals (PCDFs and PCBs), we reported marked induction of cytochrome P450 1A2 (CYP1A2) activity and this induction was an excellent biomarker of the exposure and adverse human health effects seen in the Yucheng cohort. OBJECTIVES The goal of this study was to determine the relationship between inducibility of CYP1A2 and genetic polymorphisms of AhR, ARNT, and AhRR in human. METHODS The Yucheng victims who completed blood sample collecting in 1994-1995 for serum concentrations of PCB, PCDF, and PCDD congeners, and also completed the caffeine breath tests for CYP1A2 activity were identified. From the collected blood samples, six single nucleotide polymorphisms were selected for genotyping, including AhR (rs2066853), AhRR (rs2292596), ARNT (rs7517566), ARNT (rs3820541), ARNT (rs3768016), and ARNT (rs2228099). RESULTS AhRR (rs2292596) polymorphism was significantly related to CYP1A2 inducibility (p=0.01). A linear trend test was observed between people with AhRR (rs2292596) GG, GC, and CC genotype (p=0.0014). CONCLUSION Overall, AhRR (rs2292596) genotypes predict the inducibility of CYP1A2 in people highly exposed to toxic dioxin-like chemicals. Future studies and analysis will determine to what degree these polymorphisms can predict a humans susceptibility to dioxin-related adverse human health effects.

Comprehensive approach to understand the association between diurnal temperature range and mortality in East Asia

An adverse association between diurnal temperature range (DTR) and mortality has been suggested, but with variable relationships in different cities. Comprehensive approaches to understanding the health effects of DTR using multinational data are required. We investigated the association between DTR and cause-specific mortality in an age-specific population and assessed the dependency of the health effects of DTR on geographic and climatic factors. Poisson generalized linear regression analyses with allowances for over-dispersion were applied to daily DTR and cause-specific mortality data from 30 cities in China, Japan, Korea, and Taiwan between 1979 and 2010, adjusted for various climatic and environmental factors. City-specific effects of DTR were estimated and summarized for the overall effects using geographic and climatic determinants in a meta-analysis. For all-cause, circulatory, and respiratory mortality, the greatest city-specific effects per 1°C DTR were found in Tianjin, China (1.80%; 95% confidence interval [CI]: 0.48, 3.14); Tangshan, China (2.25%; 95% CI: 0.65, 3.87); and Incheon, Korea (2.84%; 95% CI: 0.04, 5.73), respectively, and overall effects across 30 cities were 0.58% (95% CI: 0.44, 0.72), 0.81% (95% CI: 0.60, 1.03), and 0.90% (95% CI: 0.63, 1.18), respectively. Using quartile cutoff values for climatic (DTR, and mean temperature) and geographic (latitude, and longitude) characteristics, we divided the 30 cities into 4 different groups and conducted a meta-analysis within the groups using either a random or fixed effects model. Adverse effects of DTR were more pronounced for those aged ≥65years and varied according to geographic, longitudinal (0.07%; 95% CI: 0.05, 0.10), and climatic characteristics and the scale of DTR (0.33%; 95% CI: 0.12, 0.55) for overall all-cause mortality. The DTR is a risk factor affecting human health, depending on geographic location and the temperature variation, with particular vulnerability in aged populations.

Suicide and Ambient Temperature in East Asian Countries: A Time-Stratified Case-Crossover Analysis.

Background A limited number of studies suggest that ambient temperature contributes to suicide; these studies typically focus on a single nation and use temporally and spatially aggregated data. Objective We evaluated the association between ambient temperature and suicide in multiple cities in three East Asian countries. Methods A time-stratified case-crossover method was used to explore the relationship between temperature and suicide, adjusting for potential time-varying confounders and time-invariant individual characteristics. Sex- and age-specific associations of temperature with suicide were estimated, as were interactions between temperature and these variables. A random-effects meta-analysis was used to estimate country-specific pooled associations of temperature with suicide. Results An increase in temperature corresponding to half of the city-specific standard deviation was positively associated with suicide in most cities, although average suicide rates varied substantially. Pooled country-level effect estimates were 7.8% (95% CI: 5.0, 10.8%) for a 2.3°C increase in ambient temperature in Taiwan, 6.8% (95% CI: 5.4, 8.2%) for a 4.7°C increase in Korea, and 4.5% (95% CI: 3.3, 5.7%) for a 4.2°C increase in Japan. The association between temperature and suicide was significant even after adjusting for sunshine duration; the association between sunshine and suicide was not significant. The associations were greater among men than women in 12 of the 15 cities although not significantly so. There was little evidence of a consistent pattern of associations with age. In general, associations were strongest with temperature on the same day or the previous day, with little evidence of associations with temperature over longer lags (up to 5 days). Conclusions We estimated consistent positive associations between suicide and elevated ambient temperature in three East Asian countries, regardless of country, sex, and age. Citation Kim Y, Kim H, Honda Y, Guo YL, Chen BY, Woo JM, Ebi KL. 2016. Suicide and ambient temperature in East Asian countries: a time-stratified case-crossover analysis. Environ Health Perspect 124:75–80; http://dx.doi.org/10.1289/ehp.1409392

Menstrual effects among women exposed to polychlorinated biphenyls and dibenzofurans.

BACKGROUND Polychlorinated biphenyls (PCBs), dibenzofurans (PCDFs), and dibenzo-dioxins (PCDDs) may affect the female reproductive system in humans. A mass poisoning occurred in Taiwan due to PCBs/PCDFs-contaminated cooking oil, and was called the Yucheng (oil-disease in Chinese). We aimed to determine whether Yucheng women were affected in their menstruation. METHODS After the event, we followed the exposed individuals and an age-matched neighborhood reference group. Menstrual cycle characteristics and age at menarche were obtained by a telephone interview. We used multiple linear and logistic regression to examine the association between PCBs/PCDFs and menstrual cycle characteristics, after adjusting for confounding factors. RESULTS Totally 445 women responded satisfactorily and were included in the analyses of menstrual characteristics. Menstrual cycle irregularity and dysmenorrheal did not differ between Yucheng and referents. Yucheng womens menstrual cycles were 0.5 (95% CI: 0.0-0.5; p=0.03) days shorter than those of the referents. The Yucheng women with skin lesions caused by PCBs/PCDFs were more prominently affected, with the cycles 1.2 days shorter than the referents. Yucheng women exposed to PCBs/PCDFs at the premenacheal period had reduced cycle length (-0.7 day, 95% CI: -1.4 to 0.0; p=0.04) and longer days of menstrual flow (0.5 day, 95% CI: 0.0-1.0; p=0.04). Among those women who were exposed at an age of 5-9 years, menarche started slightly earlier with borderline significance. CONCLUSIONS Shorter menstrual cycle length and a longer duration of bleeding in each cycle were found among women previously exposed to PCBs/PCDFs. These effects were more obviously observed among those exposed at premenarcheal ages.

Effects of Ambient Particulate Matter and Fungal Spores on Lung Function in Schoolchildren

OBJECTIVES: Studies examining the combined health effects of both have been relatively lacking. We conducted a longitudinal study to investigate whether exposure to air pollutants and fungal spores might exacerbate childhood respiratory health. METHODS: Study participants were 100 elementary and middle-school students in Taipei County, Taiwan. A structured respiratory health questionnaire was administered in September 2007, followed by monthly spirometry from October 2007 to June 2008. During the study period, complete daily monitoring data for criteria air pollutants were obtained from the Environmental Protection Administration monitoring station and Aerosol Supersite. Fungal spores were measured from Sunday to Saturday in the week when lung-function measurements were made for each study month. Lung-function measurements were compared with air pollutants and fungal spores using mixed-effects models with 1-day-lag modeling. RESULTS: The particulate matter with an aerodynamic diameter of 2.5 μm or less level 1 day before the lung function measurements was negatively associated with forced vital capacity. The fungal spore level was negatively associated with both forced expiratory vital capacity and forced expiratory volume in 1 second. O3 level was negatively associated with forced expiratory flow at 25%, 50%, and 75% of forced vital capacity, and average expiratory flow over the middle half of forced vital capacity. CONCLUSIONS: This study suggested that exposure to particulate matter with an aerodynamic diameter of 2.5 μm or less and fungal spores might cause adverse effects on the vital capacity of schoolchildren. Exposure to O3 adversely affected small airway function.

High ambient Cladosporium spores were associated with reduced lung function in schoolchildren in a longitudinal study

BACKGROUND In our previous longitudinal study, we found that exposure to current levels of ambient total fungal spores was related to a reduction of childhood lung function. However, the biological properties of various taxa of fungal spores varied greatly, as well as their health effects. In this study, we aimed to determine whether any specific fungal spores were responsible for observed changes in lung function. METHODS Measurement of lung function was conducted for 100 elementary and middle-school students on 5-10 occasions from October 2007 to November 2009 in New Taipei City, Taiwan. During the week of each lung function measurement, continuous daily concentrations of fungal spores were measured from Sunday to Saturday. The counts of fungal spores belonging to specific taxa were identified. A mixed-effect model with repeated measurements was used to analyze the association of lung function and exposure to each specific taxon of fungal spores. Forward stepwise regression was applied to determine which specific fungal spores were the most closely related to lung function changes. The non-linear relationship was examined using a generalized additive model. The piecewise linear regression was then applied to determine the threshold value. RESULTS A total of 824 measurements were obtained from 100 participants. Among all the species of fungal spores, only Cladosporium spores were found to be negatively associated with forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) one day later. This association was stronger than the one between the total spore counts and lung function. The threshold of exposure where lung function effect became observable was approximately 1,500 spores/m(3). CONCLUSION This study showed that ambient Cladosporium was most strongly associated with the observed lung function changes among schoolchildren. Replication of these preliminary findings in other geographic areas with different populations would be warranted.