Fertilizer management for global ammonia emission reduction.

Crop production is a large source of atmospheric ammonia (NH3), which poses risks to air quality, human health and ecosystems1-5. However, estimating global NH3 emissions from croplands is subject to uncertainties because of data limitations, thereby limiting the accurate identification of mitigation options and efficacy4,5. Here we develop a machine learning model for generating crop-specific and spatially explicit NH3 emission factors globally (5-arcmin resolution) based on a compiled dataset of field observations. We show that global NH3 emissions from rice, wheat and maize fields in 2018 were 4.3 ± 1.0 Tg N yr-1, lower than previous estimates that did not fully consider fertilizer management practices6-9. Furthermore, spatially optimizing fertilizer management, as guided by the machine learning model, has the potential to reduce the NH3 emissions by about 38% (1.6 ± 0.4 Tg N yr-1) without altering total fertilizer nitrogen inputs. Specifically, we estimate potential NH3 emissions reductions of 47% (44-56%) for rice, 27% (24-28%) for maize and 26% (20-28%) for wheat cultivation, respectively. Under future climate change scenarios, we estimate that NH3 emissions could increase by 4.0 ± 2.7% under SSP1-2.6 and 5.5 ± 5.7% under SSP5-8.5 by 2030-2060. However, targeted fertilizer management has the potential to mitigate these increases.

Chronic exposure to ambient air pollution and the risk of non-alcoholic fatty liver disease: A cross-sectional study in Taiwan and Hong Kong.

BACKGROUND: Information on the relation of air pollution with non-alcoholic fatty liver disease (NAFLD) is scarce. We thus conducted a large cross-sectional study in Asia to investigate the role of air pollution in NAFLD. METHODS: We recruited 329,048 adults (mean age: 41.0 years) without other liver disease (hepatitis and cirrhosis) or excessive alcohol consumption in Taiwan and Hong Kong from 2001 to 2018. The concentrations of nitrogen dioxide (NO2) and ozone (O3) were estimated using a space-time regression model, and the concentrations of fine particulate matter (PM2.5) was evaluated using a satellite-based spatio-temporal model. NAFLD was determined using either the fatty liver index (FLI) or the hepatic steatosis index (HSI). The NAFLD-related advanced fibrosis was defined according to BARD score or the fibrosis-4 (FIB-4). A logistic regression model was adopted to explore the relationships of ambient air pollution with the odds of NAFLD and NAFLD-related advanced fibrosis. RESULTS: We found positive relationships between PM2.5 and the odds of NAFLD and advanced fibrosis, with every standard deviation (SD, 7.5 µg/m3) increases in PM2.5 exposure being associated with a 10% (95% confidence interval [CI]: 9%-11%) increment in the prevalence of NAFLD and an 8% (95% CI: 7%-9%) increment in the prevalence of advanced fibrosis. Similarly, the prevalence of NAFLD and advanced fibrosis increased by 8% (95% CI: 7%-9%) and 7% (95% CI: 6%-8%) with per SD (18.9 µg/m3) increasement in NO2 concentration, respectively. Additionally, for every SD (9.9 µg/m3) increasement in O3 concentration, the prevalence of NAFLD and advanced fibrosis decreased by 12% (95% CI: 11%-13%) and 11% (95% CI: 9%-12%), respectively. CONCLUSION: Higher ambient PM2.5 and NO2 are linked with higher odds of NAFLD and advanced fibrosis. Our findings indicate that reducing PM2.5 and NO2 concentrations may be an effective way for preventing NAFLD. Further studies on O3 are warranted.

Chronic exposure to ambient PM2.5/NO2 and respiratory health in school children: A prospective cohort study in Hong Kong.

Despite increasing concerns about the detrimental effects of air pollution on respiratory health, limited evidence is available on these effects in the Hong Kong population, especially in children. In this prospective cohort study between 2012 and 2017, we aimed to investigate the associations between exposure to air pollution (concentrations of fine particulate matter [PM2.5] and nitrogen dioxide [NO2]) and respiratory health (lung function parameters and respiratory diseases and symptoms) in schoolchildren. We recruited 5612 schoolchildren aged 6-16 years in Hong Kong. We estimated the annual average concentrations of ambient PM2.5 and NO2 at each participant's address using spatiotemporal models. We conducted spirometry tests on all participants to measure their lung function parameters and used a self-administered questionnaire to collect information on their respiratory diseases and symptoms and a wide range of covariates. Linear mixed models were used to investigate the associations between exposure to air pollution and lung function. Mixed-effects logistic regression models with random effects were used to investigate the associations of exposure to air pollution with respiratory diseases and symptoms. In all of the participants, every 5-µg/m3 increase in the ambient PM2.5 concentration was associated with changes of - 13.90 ml (95 % confidence interval [CI]: -23.65 ml, -4.10 ml), - 4.20 ml (-15.60 ml, 7.15 ml), 27.20 ml/s (-3.95 ml/s, 58.35 ml/s), and - 19.80 ml/s (-38.35 ml/s, -1.25 ml/s) in forced expiratory volume in 1 s, forced vital capacity, peak expiratory flow, and maximal mid-expiratory flow, respectively. The corresponding lung function estimates for every 5-µg/m3 increase in the ambient NO2 concentration were - 2.70 ml (-6.05 ml, 0.60 ml), - 1.40 ml (-5.40 ml, 2.60 ml), - 6.60 ml/s (-19.75 ml/s, 6.55 ml/s), and - 3.05 ml/s (-11.10 ml/s, 5.00 ml/s), respectively. We did not observe significant associations between PM2.5/NO2 exposure and most respiratory diseases and symptoms. Stratified analyses by sex and age showed that the associations between exposure to air pollution and lung function parameters were stronger in male participants and older participants (11-14 year old group) than in female participants and younger participants (6-10 year old group), respectively. Our results suggest that chronic exposure to air pollution is detrimental to the respiratory health of schoolchildren, especially that of older boys. Our findings reinforce the importance of air pollution mitigation to protect schoolchildren's respiratory health.

Impacts of pollution heterogeneity on population exposure in dense urban areas using ultra-fine resolution air quality data.

Traditional air quality data have a spatial resolution of 1 km or above, making it challenging to resolve detailed air pollution exposure in complex urban areas. Combining urban morphology, dynamic traffic emission, regional and local meteorology, physicochemical transformations in air quality models using big data fusion technology, an ultra-fine resolution modeling system was developed to provide air quality data down to street level. Based on one-year ultra-fine resolution data, this study investigated the effects of pollution heterogeneity on the individual and population exposure to particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), and ozone (O3) in Hong Kong, one of the most densely populated and urbanized cities. Sharp fine-scale variabilities in air pollution were revealed within individual city blocks. Using traditional 1 km average to represent individual exposure resulted in a positively skewed deviation of up to 200% for high-end exposure individuals. Citizens were disproportionally affected by air pollution, with annual pollutant concentrations varied by factors of 2 to 5 among 452 District Council Constituency Areas (DCCAs) in Hong Kong, indicating great environmental inequities among the population. Unfavorable city planning resulted in a positive spatial coincidence between pollution and population, which increased public exposure to air pollutants by as large as 46% among districts in Hong Kong. Our results highlight the importance of ultra-fine pollutant data in quantifying the heterogeneity in pollution exposure in the dense urban area and the critical role of smart urban planning in reducing exposure inequities.

Habitual Exercise, Air Pollution, and Pneumonia Mortality: A Longitudinal Cohort Study of Approximately 0.4 Million Adults.

In this study, we aimed to examine the combined associations of particulate matter with an aerodynamic diameter less than or equal to 2.5 µm (PM2.5) and habitual exercise with pneumonia mortality. We included 384,130 persons aged ≥18 years from Taiwan, Republic of China, during 2001-2016. We followed participants until May 31, 2019, to obtain information on vital status. A time-dependent Cox regression model was used for statistical analysis. We found that risks of pneumonia mortality were reduced by 55% (hazard ratio (HR) = 0.45, 95% confidence interval (CI): 0.36, 0.55) and 36% (HR = 0.64, 95% CI: 0.52, 0.80) in participants who engaged in high and moderate levels of exercise, respectively, as compared with inactive persons. By contrast, each 10-µg/m3 increase in chronic PM2.5 exposure was associated with a 30% (HR = 1.30, 95% CI: 1.17, 1.45) higher risk of pneumonia mortality. Risk of pneumonia death was 72% lower (HR = 0.28, 95% CI: 0.20, 0.41) for persons with a high exercise level and a low PM2.5 level. Lower risk of pneumonia mortality was associated with both higher exercise and lower PM2.5 air pollution levels. For adults exposed to different levels of PM2.5, exercise benefits remained. Our findings suggest that engaging in exercise is a safe and effective strategy for alleviating the burden of pneumonia mortality, even for people who reside in a moderately polluted area.

Long-term Exposure to Fine Particulate Matter and Mortality A Longitudinal Cohort Study of 400,459 Adults.

BACKGROUND: Cohort studies on the association between long-term exposure to fine particulate matter (PM2.5) and mortality have been well established for America and Europe, but limited and inconsistent in Asia with much higher air pollution. This study aims to investigate the associations between ambient PM2.5 and all-cause and cause-specific mortality over a period of rising and then declining PM2.5. METHODS: We enrolled a total of 400,459 adults from an open cohort between 2001 and 2016, and followed them up until 31 May 2019. We obtained mortality data from the National Death Registry maintained by the Ministry of Health and Welfare in Taiwan. We estimated ambient PM2.5 exposures using a satellite-based spatiotemporal model. We performed a Cox regression model with time-dependent covariates to investigate the associations of PM2.5 with deaths from all causes and specific causes. RESULTS: This study identified 14,627 deaths and had a total of 5 million person-years of follow-up. Each 10 µg/m3 increase in PM2.5 was associated with an increased hazard risk of 29% (95% confidence interval: 24%-35%) in all-cause mortality. Risk of death increased by 30% for natural causes, 20% for cancer, 42% for cardiovascular disease (CVD) causes, and 53% for influenza and pneumonia causes, for each 10 µg/m3 increase in PM2.5. Sensitivity analyses generally yielded similar results. CONCLUSION: Long-term exposure to ambient PM2.5 was associated with increased risks of all-cause mortality and deaths from cancers, natural causes, CVD, and influenza and pneumonia. Longitudinal study design should be encouraged for air pollution epidemiologic investigation.

Habitual exercise, chronic exposure to fine particulate matter and high-sensitivity C reactive protein in Asian adults.

OBJECTIVES: Exercise may increase the inhaled amount of air pollutants and exacerbate the adverse health effects. We investigated the combined effects of chronic exposure to fine particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) and habitual exercise on C reactive protein (CRP), a sensitive marker of inflammation. METHODS: We selected 40 209 Taiwanese adults who joined a standard medical screening programme between 2001 and 2016. The PM2.5 exposure was estimated at each participant's address using a satellite-based spatiotemporal model. Information on habitual exercise was collected using a standard self-administered questionnaire. Mixed-effects linear regression models were used to investigate the associations of CRP with PM2.5 and exercise. An interaction term of PM2.5 and exercise was introduced in the models to test the modifying effects. RESULTS: A greater amount of habitual exercise was associated with a decreased level of CRP, while a higher concentration of PM2.5 exposure was associated with an increased level of CRP. The inverse associations of habitual exercise with CRP were not modified by chronic exposure to PM2.5. The participants in the group with a low level of exercise and a high level of PM2.5 exposure exhibited a 19.1% higher level of CRP than those in the group with a high level of exercise and a low level of PM2.5 exposure (95% CI: 13.7% to 24.8%; p<0.001). The longitudinal and sensitivity analyses yielded similar results. CONCLUSIONS: Increased levels of exercise and reduced exposure levels of PM2.5 are associated with a lower CRP level. Habitual exercise reduces CRP level regardless of the levels of chronic PM2.5 exposure. Our results support that habitual exercise is a safe approach for reducing systemic inflammation to improve cardiovascular health even for people residing in relatively polluted areas.

Multi-pollutant air pollution and renal health in Asian children and adolescents: An 18-year longitudinal study.

BACKGROUND: Few studies have examined the effects of multi-pollutant air pollution on renal health, especially in children and adolescents. This study investigated the association between long-term ambient air pollution exposure and renal health in Asian children and adolescents. METHODS: This study included 10,942 children and adolescents from Taiwan and Hong Kong between 2000 and 2017. PM2.5, NO2 and O3 concentrations were estimated using satellite-based spatiotemporal regression models. Two-year average concentrations, those of the year of visit and the preceding year, were used. Linear mixed models were used to examine the association between air pollution and yearly changes in estimated glomerular filtration rate (eGFR). Cox regression models with time-dependent covariates were used to examine the association between air pollution and the development of chronic kidney disease (CKD). RESULTS: Median age of the participants was 19 years (range: 2-25). The overall average concentration of PM2.5, NO2 and O3 was 26.7 µg/m3, 44.1 µg/m3 and 51.1 µg/m3, respectively. The mean yearly change in eGFR was 0.37 µL/min/1.73 m2 and the incidence rate of CKD was 6.8 per 1,000 person-years. In single-pollutant models, each 10 µg/m3 increase in PM2.5 was associated with a 0.45 µL/min/1.73 m2 [95% confidence interval (CI): 0.28-0.63] reduction in the yearly increase in eGFR and 53% [hazard ratio (HR): 1.53 (95%CI: 1.07-2.2)] greater risk of incident CKD. Each 10 µg/m3 increase in NO2 was associated with a 7% [HR (95%CI): 1.07 (1.00-1.15)] higher risk of incident CKD, while an equivalent increase in O3 was associated with a 19% [HR (95%CI): 0.81 (0.67-0.98)] lower risk. CONCLUSIONS: Long-term exposure to ambient PM2.5 and NO2 was associated with a slower growth of eGFR and a higher risk of incident CKD in children and adolescents. Our findings suggest that air pollution control in early life is imperative to improve lifelong renal health and alleviate the CKD burden.

Total and differential white blood cell count and cause-specific mortality in 436 750 Taiwanese adults.

BACKGROUND AND AIMS: White blood cell (WBC) count is an easily obtainable biomarker of systematic inflammation. Our study aimed to investigate the associations of differential WBC count with all-cause and cause-specific mortality in a general Asian population. METHODS AND RESULTS: Cox proportional hazards model was used to evaluate the associations of WBC count with mortality separately for men and women, with adjustment for multiple variables including age, smoking, and other lifestyle factors. Stratified analyses by age, smoking, diabetes, and hypertension were conducted to explore potential effect modification. Elevated WBC count was significantly associated with increased mortality risk. The adjusted hazard ratios of total WBC (10th decile compared to decile of lowest risk) for all-cause mortality were 1.42 (95% CI: 1.33, 1.53) for men and 1.54 (95% CI: 1.42, 1.68) for women. Similar risks were observed for neutrophils, monocytes, and neutrophil/lymphocyte (NL) ratio. The highest deciles of neutrophils, monocytes, and NL ratio were also positively associated with risk of cardiovascular/cerebrovascular, cancer, and respiratory mortality after adjusting for covariates. Results for all-cause mortality remained statistically significant for participants who were <60 years old, non-smokers, non-diabetic, and non-hypertensive. CONCLUSIONS: Total and differential WBC counts (neutrophils, monocytes, and NL ratios) are positively associated with increased risk of all-cause mortality, cardiovascular and cerebrovascular, cancer, and respiratory mortality among Taiwanese adults.

Ammonia emission control in China would mitigate haze pollution and nitrogen deposition, but worsen acid rain.

China has been experiencing fine particle (i.e., aerodynamic diameters ≤ 2.5 µm; PM2.5) pollution and acid rain in recent decades, which exert adverse impacts on human health and the ecosystem. Recently, ammonia (i.e., NH3) emission reduction has been proposed as a strategic option to mitigate haze pollution. However, atmospheric NH3 is also closely bound to nitrogen deposition and acid rain, and comprehensive impacts of NH3 emission control are still poorly understood in China. In this study, by integrating a chemical transport model with a high-resolution NH3 emission inventory, we find that NH3 emission abatement can mitigate PM2.5 pollution and nitrogen deposition but would worsen acid rain in China. Quantitatively, a 50% reduction in NH3 emissions achievable by improving agricultural management, along with a targeted emission reduction (15%) for sulfur dioxide and nitrogen oxides, can alleviate PM2.5 pollution by 11-17% primarily by suppressing ammonium nitrate formation. Meanwhile, nitrogen deposition is estimated to decrease by 34%, with the area exceeding the critical load shrinking from 17% to 9% of China's terrestrial land. Nevertheless, this NH3 reduction would significantly aggravate precipitation acidification, with a decrease of as much as 1.0 unit in rainfall pH and a corresponding substantial increase in areas with heavy acid rain. An economic evaluation demonstrates that the worsened acid rain would partly offset the total economic benefit from improved air quality and less nitrogen deposition. After considering the costs of abatement options, we propose a region-specific strategy for multipollutant controls that will benefit human and ecosystem health.

Habitual exercise is associated with reduced risk of diabetes regardless of air pollution: a longitudinal cohort study.

AIMS/HYPOTHESIS: Physical activity may increase a person's inhalation of air pollutants and exacerbate the adverse health effects. This study aimed to investigate the combined associations of chronic exposure to particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) and habitual physical activity with the incidence of type 2 diabetes in Taiwan. METHODS: We selected 156,314 non-diabetic adults (≥18 years old) who joined an ongoing longitudinal cohort between 2001 and 2016. Incident type 2 diabetes was identified at the follow-up medical examinations. Two-year mean PM2.5 exposure was estimated at each participant's address using a satellite-based spatiotemporal model. Information on physical activity and a wide range of covariates was collected using a standard self-administered questionnaire. We analysed the data using a Cox regression model with time-varying covariates. An interaction term between PM2.5 and physical activity was included to examine the overall interaction effects. RESULTS: Compared with high physical activity, moderate and inactive/low physical activity were associated with a higher risk of diabetes (HR [95% CI] 1.31 [1.22, 1.41] and 1.56 [1.46, 1.68], respectively). Participants with moderate/high PM2.5 had a higher risk of type 2 diabetes than the participants exposed to low PM2.5 (HR 1.31 [1.22, 1.40] and 1.94 [1.76, 2.14], respectively). The participants with high physical activity and low PM2.5 had a 64% lower risk of type 2 diabetes than those with inactive/low physical activity and high PM2.5. CONCLUSIONS/INTERPRETATION: Higher physical activity and lower PM2.5 exposure are associated with lower risk of type 2 diabetes. Habitual physical activity can reduce the risk of diabetes regardless of the levels of PM2.5 exposure. Our results indicate that habitual physical activity is a safe diabetes prevention strategy for people residing in relatively polluted regions.

Independent and Opposing Associations of Habitual Exercise and Chronic PM2.5 Exposures on Hypertension Incidence.

BACKGROUND: We investigated the joint associations of habitual physical activity (PA) and long-term exposure to fine particulate matter (PM2.5) with the development of hypertension in a longitudinal cohort in Taiwan. METHODS: We selected 140 072 adults (≥18 years of age) without hypertension who joined a standard medical screening program with 360 905 medical examinations between 2001 and 2016. PM2.5 exposure was estimated at each participant's address using a satellite data-based spatiotemporal model with 1 km2 resolution. Information on habitual PA and a wide range of covariates was collected using a standard self-administered questionnaire. We used the Cox regression model with time-dependent covariates to examine the joint associations. RESULTS: The mean age of all observations was 41.7 years, and 48.8% were male. The mean value for systolic and diastolic blood pressure was 112.5 and 68.7mm Hg, respectively. Approximately 34.2% of all observations were inactive (0 metabolic equivalence values-hours), 29.8% had moderate-PA (median [interquartile range]; 3.75 [3.38 to 4.38] metabolic equivalence values-hours), and 36.0% had high-PA (15.7 [10.3 to 24.8] metabolic equivalence values-hours). The mean±SD of PM2.5 was 26.1±7.3 µg/m3. The prevalence of cardiovascular disease, diabetes mellitus, and cancer was 2.1%, 2.9%, and 1.5%, respectively. After adjusting for a wide range of covariates (including a mutual adjustment for PA or PM2.5), a higher PA level was associated with a lower risk of hypertension (hazard ratio [HR] for the moderate- and high-PA was 0.93 [95% CI, 0.89-0.97] and 0.92 [95% CI, 0.88-0.96], respectively, as compared with the inactive-PA), whereas a higher level of PM2.5 was associated with a higher risk of hypertension (HR for the moderate- and high-PM2.5 was 1.37 [95% CI, 1.32-1.43] and 1.92 [95% CI, 1.81-2.04], respectively, as compared with the low-PM2.5 group]. No significant interaction was observed between PA and PM2.5 (HR 1.01 [95% CI, 1.00-1.02]). CONCLUSIONS: A high-PA and low PM2.5 exposure were associated with a lower risk of hypertension. The negative association between PA and hypertension remained stable in people exposed to various levels of PM2.5, and the positive association between PM2.5 and hypertension was not modified by PA. Our results indicated that PA is a suitable hypertension prevention strategy for people residing in relatively polluted regions.

Associations of Reduced Ambient PM2.5 Level With Lower Plasma Glucose Concentration and Decreased Risk of Type 2 Diabetes in Adults: A Longitudinal Cohort Study.

It remains unknown whether reduced air pollution levels can prevent type 2 diabetes mellitus. In this study, we investigated the associations between dynamic changes in long-term exposure to ambient fine particulate matter, defined as particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5), and changes in fasting plasma glucose (FPG) levels and incidence of type 2 diabetes. A total of 151,398 adults (ages ≥18 years) were recruited in Taiwan between 2001 and 2014. All participants were followed up for a mean duration of 5.0 years. Change in PM2.5 (ΔPM2.5) was defined as the value at a follow-up visit minus the corresponding value at the immediately preceding visit. The PM2.5 concentration in Taiwan increased during 2002-2004 and began to decrease in 2005. Compared with participants with little or no change in PM2.5 exposure, those with the largest decrease in PM2.5 had a decreased FPG level (ß = -0.39, 95% confidence interval: -0.47, -0.32) and lower risk of type 2 diabetes (hazard ratio = 0.86, 95% confidence interval: 0.80, 0.93). The sensitivity analysis and analyses stratified by sex, age, body mass index, smoking, alcohol drinking, and hypertension generally yielded similar results. Improved PM2.5 air quality is associated with a better FPG level and a decreased risk of type 2 diabetes development.

Effects of air pollution and habitual exercise on the risk of death: a longitudinal cohort study.

BACKGROUND: Exercise may exacerbate the adverse health effects of air pollution by increasing the inhalation of air pollutants. We investigated the combined effects of long-term exposure to fine particle matter (PM2.5) and habitual exercise on deaths from natural causes in Taiwan. METHODS: We recruited 384 130 adults (aged ≥ 18 yr) with 842 394 medical examination records between 2001 and 2016, and followed all participants until May 31, 2019. We obtained vital data from the National Death Registry of Taiwan. We estimated PM2.5 exposure using a satellite-based spatiotemporal model, and collected information on exercise habits using a standard self-administered questionnaire. We analyzed the data using a Cox regression model with time-dependent covariates. RESULTS: A higher level of habitual exercise was associated with a lower risk of death from natural causes, compared with inactivity (hazard ratio [HR] 0.84, 95% confidence interval [CI] 0.80-0.88 for the moderate exercise group; HR 0.65, 95% CI 0.62-0.68 for the high exercise groups), whereas a higher PM2.5 exposure was associated with a higher risk of death from natural causes compared with lower exposure (HR 1.02, 95% CI 0.98-1.07, and HR 1.15, 95% CI 1.10-1.20, for the moderate and high PM2.5 exposure groups, respectively). Compared with inactive adults with high PM2.5 exposure, adults with high levels of habitual exercise and low PM2.5 exposure had a substantially lower risk of death from natural causes. We found a minor, but statistically significant, interaction effect between exercise and PM2.5 exposure on risk of death (HR 1.03 95% CI 1.01-1.06). Subgroup analyses, stratified by PM2.5 categories, suggested that moderate and high levels of exercise were associated with a lower risk of death in each PM2.5 stratum, compared with inactivity. INTERPRETATION: Increased levels of exercise and reduced PM2.5 exposure are associated with a lower risk of death from natural causes. Habitual exercise can reduce risk regardless of the levels of PM2.5 exposure. Our results suggest that exercise is a safe health improvement strategy, even for people residing in relatively polluted regions.

Reduced Ambient PM2.5 Was Associated with a Decreased Risk of Chronic Kidney Disease: A Longitudinal Cohort Study.

Many countries have dedicated to the mitigation of air pollution in the past several decades. However, evidence of beneficial effects of air quality improvement on chronic kidney disease (CKD) remains limited. We thus investigated the effects of dynamic changes (including deterioration and improvement) in air quality on the incidence of CKD in a longitudinal study in Taiwan. During 2001-2016, this study recruited a total of 163,197 Taiwanese residents who received at least two standard physical examinations. The level of fine particle matter (PM2.5) was estimated using a high-resolution (1 km2) satellite-based spatio-temporal model. We defined changes of PM2.5 concentrations (ΔPM2.5) as the difference between the two-year average measurements during follow-up and during the immediately preceding visit. The time-dependent Cox regression model was adopted to evaluate the relationships between ΔPM2.5 and the incidence of CKD after adjusting for a series of covariates. The concentrations of PM2.5 in Taiwan peaked around 2004 and began to decrease since 2005. We observed an approximate linear concentration-response relationship of ΔPM2.5 with CKD incidence. Every 5 µg/m3 decrease in the ambient concentration of PM2.5 was associated with a 25% reduced risk of CKD development [hazard ratio (HR): 0.75; 95% CI: 0.73, 0.78]. In conclusion, this study demonstrated that the improvement of PM2.5 air quality might be associated with a lower risk of CKD development. Our findings indicate that reducing air pollution may effectively prevent the development of CKD.

Factors affecting variability in gaseous and particle microenvironmental air pollutant concentrations in Hong Kong primary and secondary schools.

School-age children are particularly susceptible to exposure to air pollutants. To quantify factors affecting children's exposure at school, indoor and outdoor microenvironmental air pollutant concentrations were measured at 32 selected primary and secondary schools in Hong Kong. Real-time PM10 , PM2.5 , NO2, and O3 concentrations were measured in 76 classrooms and 23 non-classrooms. Potential explanatory factors related to building characteristics, ventilation practice, and occupant activities were measured or recorded. Their relationship with indoor measured concentrations was examined using mixed linear regression models. Ten factors were significantly associated with indoor microenvironmental concentrations, together accounting for 74%, 61%, 46%, and 38% of variations observed for PM2.5 , PM10 , O3, and NO2 microenvironmental concentrations, respectively. Outdoor concentration is the single largest predictor for indoor concentrations. Infiltrated outdoor air pollution contributes to 90%, 70%, 75%, and 50% of PM2.5 , PM10 , O3, and NO2 microenvironmental concentrations, respectively, in classrooms during school hours. Interventions to reduce indoor microenvironmental concentrations can be prioritized in reducing ambient air pollution and infiltration of outdoor pollution. Infiltration factors derived from linear regression models provide useful information on outdoor infiltration and help address the gap in generalizable parameter values that can be used to predict school microenvironmental concentrations.

An improved decomposition method to differentiate meteorological and anthropogenic effects on air pollution: A national study in China during the COVID-19 lockdown period.

Although the effects of meteorological factors on severe air pollution have been extensively investigated, quantitative decomposition of the contributions of meteorology and anthropogenic factors remains a big challenge. The novel coronavirus disease 2019 (COVID-19) pandemic affords a unique opportunity to test decomposition method. Based on a wind decomposition method, this study outlined an improved method to differentiate complex meteorological and anthropogenic effects. The improved method was then applied to investigate the cause of unanticipated haze pollution in China during the COVID-19 lockdown period. Results from the wind decomposition method show that weakened winds increased PM2.5 concentrations in the Beijing-Tianjin area and northeastern China (e.g., by 3.19 µg/m3 in Beijing). Using the improved decomposition method, we found that the combined meteorological effect (e.g., drastically elevated humidity levels and weakened airflow) substantially increased PM2.5 concentrations in northern China: the most substantial increases were in the Beijing-Tianjin-Hebei region (e.g., by 26.79 µg/m3 in Beijing). On excluding the meteorological effects, PM2.5 concentrations substantially decreased across China (e.g., by 21.84 µg/m3 in Beijing), evidencing that the strict restrictions on human activities indeed decreased PM2.5 concentrations. The unfavorable meteorological conditions, however, overwhelmed the beneficial effects of emission reduction, causing the severe haze pollution. These results indicate that the integrated meteorological effects should be considered to differentiate the meteorological and anthropogenic effects on severe air pollution.

Reducing the Influence of Environmental Factors on Performance of a Diffusion-Based Personal Exposure Kit.

Sensor technology has enabled the development of portable low-cost monitoring kits that might supplement many applications in conventional monitoring stations. Despite the sensitivity of electrochemical gas sensors to environmental change, they are increasingly important in monitoring polluted microenvironments. The performance of a compact diffusion-based Personal Exposure Kit (PEK) was assessed for real-time gaseous pollutant measurement (CO, O3, and NO2) under typical environmental conditions encountered in the subtropical city of Hong Kong. A dynamic baseline tracking method and a range of calibration protocols to address system performance were explored under practical scenarios to assess the performance of the PEK in reducing the impact of rapid changes in the ambient environment in personal exposure assessment applications. The results show that the accuracy and stability of the ppb level gas measurement is enhanced even in heterogeneous environments, thus avoiding the need for data post-processing with mathematical algorithms, such as multi-linear regression. This establishes the potential for use in personal exposure monitoring, which has been difficult in the past, and for reporting more accurate and reliable data in real-time to support personal exposure assessment and portable air quality monitoring applications.

Does fine particulate matter (PM2.5) affect the benefits of habitual physical activity on lung function in adults: a longitudinal cohort study.

BACKGROUND: Physical activity (PA) increases a person's inhalation of air pollutants due to greater ventilation, possibly leading to larger adverse health effects. This study aims to investigate the combined effects of long-term exposure to fine particulate matter (PM2.5) and habitual PA on lung function in adults. METHODS: This was a longitudinal cohort study that included 278,065 Taiwan residents with an age of 20 years old or above who joined a standard medical screening programme between 2001 and 2014. Each participant received at least one medical examination (including spirometric, blood, and urinary tests and a standard self-administered questionnaire survey) during the study period. We estimated the 2-year average PM2.5 concentrations at each participant's address using a new physical model based on observational data. Information on the participants' PA was collected using the standard self-administrated questionnaire. Generalised linear mixed models were used to investigate the combined effects of PM2.5 and PA on pulmonary function. We also performed stratified analyses by different levels of PM2.5 exposure and habitual PA. RESULTS: Each 10 MET-h increase in PA was associated with a higher level of 0.20%, 0.16%, and 0.19% in forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and maximum mid-expiratory flow (MMEF), respectively, after adjusting for PM2.5 exposure and a wide range of covariates including age, sex education, body mass index, lifestyles, and health conditions. Each 10 µg/m3 increase in PM2.5 was associated with a lower FVC, FEV1, and MMEF (2.43%, 2.78% and 3.10%, respectively). Negative interactions were observed, and PM2.5 exposure was associated with a greater reduction in lung function among the participants with higher PA levels. CONCLUSIONS: We found significant negative interaction effects between long-term exposure to PM2.5 and habitual PA, suggesting that the increased intake of PM2.5 due to PA may attenuate the benefits of habitual PA on lung function. However, the PA benefits generally remained stable at different stratum of PM2.5 in the stratified analyses, and habitual PA may still be recommended to people residing in relatively polluted regions.

Estimations of Long-Term nss-SO42- and NO3- Wet Depositions over East Asia by Use of Ensemble Machine-Learning Method.

Wet deposition of non-sea-salt sulfate (nss-SO42-) and nitrate (NO3-), derived from anthropogenic emissions of SO2 and NOx, exerts adverse effects on ecosystems. In this work, an ensemble back-propagation neural network was proposed to estimate the long-term wet depositions of nss-SO42- (2005-2017) and NO3- (2001-2014) over East Asia in 10 km resolution. The R2 values for the 10-fold cross-validation of annual wet depositions of nss-SO42- and NO3- were 0.90 and 0.85, respectively. The hotspots of the wet deposition of these two acidic species span southwestern, central, and eastern China. The molar ratio of NO3- to nss-SO42- increased in 10 out of 12 analyzed East Asian countries from 2005 to 2014, which indicates that the acidity in rainwater shifts from the sulfur type to nitrogen type over most of the regions. The wet deposition on the four ecosystems (forest, grassland, cropland, and freshwater body) was also analyzed. Results showed that the nss-SO42- wet deposition on 25.5% of freshwater bodies in 2015 and NO3- wet deposition on 21.7% of grassland in 2014 exceeded the ecosystem empirical critical loads (25 kg/ha sulfate and 2 kg N/ha) in East Asia. Thus, more stringent and regionally collaborative sulfur and nitrogen emission-control measures are urgently needed to protect the ecosystem of East Asia.