Assessment of temporal variation for the risk of particulate matters on asthma hospitalization.

Increased ambient concentration of particulate matters are considered as one of major causes for increased prevalence or exacerbation of asthma or asthma like symptoms. Recently, possible temporal variation in risks of PM on mortality has been suggested. We investigated short-term effect of both PM10 and PM2.5 on asthma hospitalization, and assessed temporal variation of PM risks in Seoul, Korea, 2003-2011. Generalized additive model was used to estimate PM risks on asthma hospitalization with consideration by long-term trend, influenza epidemic, day of week, meteorological factors. To assess temporal variation of PM risks, year-round PM risks were estimated. Stratified analysis by season and age-group were also conducted. Estimated RRs of PM on asthma hospitalization by an increase of 10㎍/㎥were 1.0084 (95% CI: 1.0041-1.0127) and 1.0156 (95% CI: 1.0055-1.0259) respectively with 7-days lag periods (lag06). PM2.5 had stronger effect than PM10 for all age group. Elderly group was most affected by PM. For the analysis of temporal variation of PM risks, we found increasing trend in total population and the elderly group. In the season-specific analysis, we also found increasing trend in winter for PM10, and in spring for PM2.5. PM10 and PM2.5 has adverse effect on asthma hospitalization with evidence suggesting temporal variation in PM risks. Further research will be needed to confirm the temporal variation of PM risk on asthma hospitalization, and to identify casual factors affecting this temporal variation. This study results could be evidentiary materials for establishing valid public health policies to reduce health burden or economic burden of asthma.

Effects of ambient air particles on mortality in Seoul: Have the effects changed over time?

BACKGROUND: Several studies have shown that there may be temporal variation in PM short-term effect on mortality. This temporal pattern may play an important role in evaluating air quality policies. OBJECTIVES: We investigated temporal variation in the association between PM and mortality in Seoul, Korea, 1998-2011. METHODS: We adopted a generalized additive model and a series of time windows of five years to analyze temporal variation in associations between PM and all-cause, cardiovascular, and respiratory mortality. This time-window approach offers not only a comparison between one and the other half period but also successive variation. Time-varying associations were estimated only for days without Asian dust (dust storm blown from the Gobi desert) intrusion. RESULTS: Annual average PM10 and PM2.5 total mass decreased from 70.0 to 46.9 µg/m(3) and 44.4 to 23.4 µg/m(3), respectively, during 2001-2011. A 10 µg/m(3) increase in PM10 was associated with 0.16% (95% CI=-0.03% to 0.35%) additional all-cause deaths in 2002-2006 and it increased to 0.26% (95% CI=0.05-0.48%) in 2007-2011. For PM2.5, the association increased from 0.35% (95% CI=-0.02% to 0.71%) to 0.48% (95% CI=0.08-0.88%). For cardiovascular and respiratory mortality, increasing trends with stronger estimates were found. CONCLUSIONS: The present study showed temporally increasing trends in associations between PM and mortality. Current policies may not be as effective to reducing health risks attributable to PM as expected. Air quality interventions should be encouraged in terms of causal factors for time-varying association between PM and mortality.

Effect of solar irradiation on serum specific immunoglobulin E to house-dust mite.

BACKGROUND: The relationship between sensitization to Dermatophagoides species and solar irradiation, as reflected by vitamin D, remains elusive. OBJECTIVE: We investigated the lag time and the cumulative and maximum effects of exposure to solar irradiation on sensitization to house-dust mites. METHODS: A time series study design was applied to solar irradiation (MJ/m(2)) and relative humidity (%) for specific immunoglobulin E (IgE) levels against Dermatophagoides pteronyssinus (n = 20,451) and Dermatophagoides farinae (n = 22,824). We used the distributed lag nonlinear model to assess the difference of log IgE to house-dust mites in relation to climate variables. RESULTS: Compared with specific IgE levels of those exposed to 18 MJ/m(2), the maximum increase in sensitization to D. pteronyssinus was observed at a solar irradiation of 10 MJ/m(2) at peak 0 week (difference of log IgE 0.368 [95% confidence interval (CI), 0.209-0.529], p < 0.001), and this increase continued for 3 weeks. The IgE level was significantly affected by the relative humidity of the 3rd- to 12th-lag week, and the effect reached its peak at 75% on the 8th week (difference of log IgE 0.394 [95% CI, 0.221-0.566], p < 0.001). The logistic regression analysis showed that solar irradiation was associated with a decreased risk to sensitization to D. pteronyssinus (odds ratio 0.988 per 1 MJ/m(2) [95% CI, 0.979-0.997], p < 0.013) on the testing week after controlling for humidity and temperature. CONCLUSION: This study demonstrated that low solar irradiation immediately increased the risk of sensitization to two house-dust mite species. Further research is warranted to delineate the underlying mechanism of the effect of solar irradiation on aeroallergen sensitization.

A Study on the Preliminary Plan for Environmental Health in Seoul, Korea.

In the Republic of Korea, the Environmental Health Act was amended in January 2021, making it mandatory for each local government to establish a plan for environmental health. Accordingly, the Seoul Metropolitan Government (SMG) must establish the Local Plan for Environmental Health (LPEH) to protect citizens' health from environmental hazards. The plan would support existing environmental health policies in Seoul to improve population health and achieve their goals. As a proof-of-concept to establish the LPEH, we developed a preliminary plan for environmental health in Seoul. We analyzed environmental health conditions of Seoul, identified driving conditions for execution of environmental health policies, set basic policy directions, and identified tasks needed to establish the preliminary plan. As a result, we established the vision and the goals of the preliminary plan. The vision is "a safe Seoul environment, healthy citizens". The strategies are "active monitoring of environmental health issues", "minimization of health damage and meticulous and systematic response", and "building a foundation for environmental health". To achieve the vision and the goals, we developed three strategies, eight tasks, and 25 sub-tasks. Under the preliminary plan we developed, we expect that SMG is able to protect citizens' health from threats of environmental hazards; improve environmental health conditions, especially in susceptible populations such as infants; and promote environmental justice.

Asymmetric Divergent Total Syntheses of (+)-Decursivine and (+)- Serotobenine via Intramolecular Fischer Indole Synthesis.

A new asymmetric synthetic route to (+)-decursivine and (+)-serotobenine is formulated. The key developments are the de novo construction of the crucial eight-membered 3,4-fused tricyclic indole ring engaged by the intramolecular Fischer indole synthesis and the stereocontrolled assembly of the dihydrobenzofuran subunit mediated by the asymmetric intramolecular Rh-carbenoid C-H insertion. BF3-mediated selective C15 epimerization followed by removal of the amine masking groups completed the target natural compounds' asymmetric and divergent total syntheses.

Effect of air pollutant emission reduction policies on hospital visits for asthma in Seoul, Korea; Quasi-experimental study.

To improve air quality and reduce adverse health effects due to air pollutants, Seoul metropolitan government has introduced emission reduction policies in Seoul metropolitan area since 2007. As a result, air quality in Seoul has improved. However, no study has reported whether emission reduction policies have affected respiratory morbidities in Korea. Thus, we aimed to assess an association between air pollutant emissions and ambient concentrations, and the effect of implemented emission reduction policies on asthma. The population of Daejeon, one of the metropolitan cities in Korea other than Seoul was used as a reference population to adjust for possible long-term background trend. Trends of air pollutant emissions, ambient concentrations, and hospital visit rates in Seoul and Daejeon were evaluated using descriptive statistics. To evaluate the possible beneficial effect of air pollutant emission reduction policies implemented since 2007 on hospital visits for asthma in Seoul, we conducted interrupted time-series analysis. As a result, we found evidence for the association between emission reductions and reduced ambient concentrations. Trends in hospital visit rates for asthma, which were previously increasing in Seoul, have decreased since the implementation of the policies. Prevented hospital visits cases for asthma in the total population and younger population (0-18 years) were estimated as 500,000 (11.3% of hospital visit cases if there was no intervention) cases and 320,000 (15.5% of hospital visit cases if there was no intervention) cases, respectively in Seoul. Our study provides evidence for the possible beneficial effect of emission reduction policies on hospital visits for asthma.

Spatial variation in lag structure in the short-term effects of air pollution on mortality in seven major South Korean cities, 2006-2013.

Lag is one of the major uncertainties in the heterogeneity of short-term effects of particulate matter with aerodynamic diameter <10 µm (PM10) on mortality. This study aimed to explore spatial variations in extended lag effects of PM10 on all-cause mortality, cardiovascular mortality and respiratory mortality in seven major South Korean cities over a period spanning 2006-2013. We did time-series analysis using generalized linear models and adjusted for temporal trend, day of the week, holiday, influenza epidemic, and weather. Single lag models and distributed lag models were extensively compared, specifically in terms of lag interval, and adjustment for temporal trend. We also conducted a time-stratified case-crossover analysis. Multivariate meta-regressions with city characteristic variables were conducted in order to assess spatial variation in the lag structure. When considering up to previous 45 days of exposure, we found longer lag associations between PM10 and mortality, particularly in all-cause mortality and respiratory mortality. SO2, the ratio of SO2 to PM10 and gross regional domestic product were all found to positively contribute towards the associations between PM10 and all-cause mortality and cardiovascular mortality. Ulsan (Korea's largest industrial city) was found to have the strongest cumulative percentage increases in all-cause mortality and cardiovascular mortality per 10 µg/m3 increase of PM10: 4.9% (95% CI: 2.5, 7.3) and 4.3% (95% CI: -0.9, 9.7) respectively. Busan (Korea's largest seaport city) was found to have the highest cumulative percentage increase in respiratory mortality with an 8.2% increase (95% CI: 2.8, 13.8). In summary, the short-term effects of PM10 on mortality may persist over a period of not just few weeks but longer than a month, and may differ according to regional economy. This study provides public health implication that, in order to minimize the health effects of PM, air quality interventions should focus on not only particulate pollution but also gaseous pollution, such as SO2.

Difference in temporal variation of temperature-related mortality risk in seven major South Korean cities spanning 1998-2013.

Temporal variation of temperature-related mortality risk is an important issue in climate change era. However, difference in this temporal variation across cities in South Korea remains unclear. The aim of this study was to explore whether temporal variation might differ spatially across seven metropolitan cities of Korea during the period of 1998-2013. We estimated cumulative associations between temperature (up to previous 14 days of exposure) and all-cause mortality, and compared cumulative associations between the first eight years (1998-2005) and the last eight years (2006-2013). Multivariate meta-regression analysis was performed to investigate what factors might be associated with spatial and temporal variation in cumulative associations. We found that Busan, Daegu, and Gwangju experienced decrease in heat effect from 1998-2005 to 2006-2013, while Incheon experienced increase in heat effect. By comparing mortality risk at 99th percentile of temperature to mortality risk at minimum mortality temperature, percentage increase of mortality risk changed from 4.8% (95% CI: -1.3, 11.3) to 0.4% (95% CI: -6.0, 7.4) in Busan, from 17.2% (95% CI: 10.2, 24.7) to 4.0% (95% CI: -1.4, 9.8) in Daegu, from 20.3% (95% CI: 11.5, 29.7) to 2.2% (95% CI: -3.5, 8.3) in Gwangju, and from 3.5% (95% CI: 0.2, 6.8) to 7.9% (95% CI: 5.0, 10.9) in Incheon, respectively. Change in average temperature from 1998-2005 to 2006-2013 was negatively associated with change in heat effect even though average temperature in most of the cities fluctuated over time. We also found that all seven cities had decrease in effect of moderate cold temperature from 1998-2005 to 2006-2013. Such decrease was associated with improvement in medical resources. Results of this study suggest that plans for adaptation to temperature-related risks should differ across populations because adaptation to temperature varies across populations and within the same population over different time.

Association between Urban Greenness and Depressive Symptoms: Evaluation of Greenness Using Various Indicators.

An increasing number of studies have suggested benefits of greenness exposure on mental health. We examined the association between urban greenness and depressive symptoms in adults in the general population living in the seven major cities in Korea (N = 65,128). Using data from the Korean Community Health Survey 2009, depressive symptoms were measured on the Center for Epidemiological Studies Depression Scale (CES-D). Greenness was assessed using Normalized Difference Vegetation Index (NDVI) and land-use data (forest area and forest volume). Logistic regression models were fitted to adjust for potential confounders. Individuals in regions with the highest NDVI (quartile 4) had the lowest odds for depressive symptoms compared to quartile 1, after adjusting for potential confounders (OR = 0.813; 95% CI: 0.747, 0.884). For all greenness indicators except for forest area per district area (%), the highest rate of depressive symptoms was found for the individuals in the lowest quartile of greenness (quartile 1) and the lowest rate of depressive symptoms for those in the highest quartile of greenness (quartile 4). We found an inverse association between urban greenness and depressive symptoms, which was consistent across a variety of greenness indicators. Our study suggests health benefits of greenness and could provide a scientific basis for policy making and urban planning.

Assessing the cold temperature effect on hospital visit by allergic rhinitis in Seoul, Korea.

The association between temperature and health outcome has been studied in worldwide. However, studies for mild diseases such as AR, with high prevalence and considerable economic burden, are lacking compared to other relatively severe respiratory diseases. We aimed to assess the trend of hospital visit by AR and estimate the cold temperature effect on hospital visit by allergic rhinitis in Seoul, Korea, 2003-2011. We fitted generalized additive model with quasi-poisson distribution, controlling for humidity, long-term trend, day of week, national holiday, and influenza epidemic. We estimated the cumulative cold temperature effect (10%, -1.7°C) referent to 7.9°C for the considered lag periods using distributed lag non-linear model: vary from the day of hospital visit to 10days before. Stratified analysis by season was also conducted. To adjust for possible confounding effect of air pollutants, we additionally adjusted for PM10, O3 and NO2 respectively. Hospital visit counts and rates per 1,000,000 show increasing trend especially in elderly population (over 65years). Hospital visit rate is higher in children population (age<13years). Statistically significant cold temperature effects were found in the total (1.094(95%CI: 1.037, 1.153)), male (1.100 (95%CI: 1.010, 1.163)), female (1.088 (95%CI: 1.059, 1.170)) and adult (1.113 (95%CI: 1.059, 1.170)) population with consideration of 3-day lag period. In the stratified analysis by the season, the strongest effect was shown in the autumn (Sep-Nov) season. Confounding effects by air pollutants were not found. In this study, we found significant increasing trend of hospital visit by AR. This study provides suggestive evidence of cold temperature effect on hospital visit by AR. To reduce the growing burden of AR, it is important to find possible related environmental risk factors. More studies should be conducted for better understanding of temperature effect on AR.

Has the impact of temperature on mortality really decreased over time?

Many studies have reported that the temperature effect on mortality has decreased over time. However, most of those studies did not consider lag times longer than 10 days, which is frequently used to explore its effect net out compensatory effect (harvesting) and lag effects. We sought to examine the temporal variation of the temperature effect on mortality, considering both a lag effect and mortality displacement. Time-series analysis was conducted with lag of temperature up to 21 days on all-cause, cardiovascular, cerebrovascular, and respiratory deaths. We applied a series of time-windows, 8 years long, with which we compared the oldest to more recent intervals and took consecutive annual variation, excluding an interannual harvesting effect. At the 99th percentile (29°C), relative to the 90th percentile (25°C), we found a decreasing trend of heat effect on concurrent days whereas the risk of cardiovascular deaths increased over time. Cumulative risks of deaths increased recently except for respiratory disease. At the 10th percentile (-1°C) relative to the 25th percentile (4°C), cumulative cold effects on cardiovascular and respiratory mortality have emerged recently. Our study showed differences in the temporal variation in the temperature effect on mortality at concurrent day and in cumulative term. It is suggested that the time-varying nature of the temperature-mortality relationship depends not only on suggested factors, such as improvements in technology and infrastructure, and human physiological acclimatization, but also mortality displacement and lagged effects. Further studies on its complex nature are needed to provide relevant evidence for public health policy making.

Plasma calcium and risk of hypertension: propensity score analysis using data from the korean genome and epidemiology study.

OBJECTIVE: To investigate associations between plasma calcium and future incidence of hypertension in a healthy population. METHODS: We used prospective data from Ansung and Ansan cohorts (n = 10,038) of the Korean Genome and Epidemiology Study. Data from baseline (2001-02) to the fourth study (2007-08) were used. After excluding hypertensive cases at baseline, missing data, and outliers, 5560 participants were analyzed. Propensity scores for having higher plasma calcium (≥2.37 mmol/L) were created for each participant. After propensity score matching (1:1 nearest neighbor matching within caliper), 2153 pairs were left for analysis. Factors that were significantly different between the lower and higher plasma calcium groups before matching either became nonsignificant or the difference decreased in size. RESULTS: Using multivariable Cox proportional hazard models with robust standard errors accounting for clustering of matched pairs, higher plasma calcium was associated with higher incidence of hypertension (adjusted HR, 1.24; robust 95%CI, 1.07-1.43). Among those with higher plasma calcium, low dietary calcium intake increased the development of hypertension, but the effect was not significant. Sensitivity analysis showed that our results were robust to hidden bias. CONCLUSIONS: Plasma calcium was positively associated with incidence of hypertension. These results expand on cross-sectional associations between hypercalcemia and the metabolic syndrome, and extend the link to future risk of hypertension.