Spatio-temporal patterns of the minimum rest time for outdoor workers exposed to summer heat stress in South Korea.

In this study, the spatio-temporal characteristics of the minimum rest time for the safety of South Korean outdoor workers during hot summer months (June to August) are examined based on the hourly wet-bulb globe temperature (WBGT) across 27 weather stations in South Korea. The WBGT thresholds in the work-rest recommendation of the Korea Occupational Safety and Health Agency (KOSHA 2017) for the quantification of the minimum rest time are evaluated through a comparison of the given thresholds with the occurrences of occupational heat-related illness patients due to outdoor work during hot summer months in South Korea. The long-term (2009-2018) average of the hourly WBGT values during summer months shows that outdoor workers with a moderate workload are exposed to heat stress during approximately 30% of the entire daytime working hours (06:00-18:00). According to the WBGT thresholds modified from the KOSHA (2017) guidelines, the daily minimum rest time for a moderate workload noticeably increases up to 18% (11 min/h) in mid-summer (late July and early August). During mid-summer, the minimum rest time for a continuous moderate outdoor workload even increases up to 31% (18 min/h) between 12:00 and 13:00 and is regionally higher in the southwestern than in the southeastern regions of the Korean Peninsula. These results suggest that in summertime high-heat environments, a mandatory rest time must be provided according to appropriate heat management programs for the safety of workers.

Effects of heat waves on daily excess mortality in 14 Korean cities during the past 20 years (1991-2010): an application of the spatial synoptic classification approach.

The aims of this study are to explore the "offensive" summer weather types classified under the spatial synoptic classification (SSC) system and to evaluate their impacts on excess mortality in 14 Korean cities. All-cause deaths per day for the entire population were examined over the summer months (May-September) of 1991-2010. Daily deaths were standardized to account for long-term trends of subcycles (annual, seasonal, and weekly) at the mid-latitudes. In addition, a mortality prediction model was constructed through multiple stepwise regression to develop a heat-health warning system based on synoptic climatology. The result showed that dry tropical (DT) days during early summer caused excess mortality due to non-acclimatization by inhabitants, and moist tropical (MT) plus and double plus resulted in greater spikes of excess mortality due to extremely hot and humid conditions. Among the 14 Korean cities, highly excess mortality for the elderly was observed in Incheon (23.2%, 95%CI 5.6), Seoul (15.8%, 95%CI 2.6), and Jeonju (15.8%, 95%CI 4.6). No time lag effect was observed, and excess mortality gradually increased with time and hot weather simultaneously. The model showed weak performance as its predictions were underestimated for the validation period (2011-2015). Nevertheless, the results clearly revealed the efficiency of relative and multiple-variable approaches better than absolute and single-variable approaches. The results indicate the potential of the SSC as a suitable system for investigating heat vulnerability in South Korea, where hot summers could be a significant risk factor.

Ipsilateral pleural recurrence after diagnostic transthoracic needle biopsy in pathological stage I lung cancer patients who underwent curative resection.

OBJECTIVES: The relationship between transthoracic needle biopsy (TTNB) and pleural recurrence of cancer after curative lung resection remains unclear. We aimed to assess whether TTNB increases the ipsilateral pleural recurrence (IPR) rate and identify other potential risk factors for pleural recurrence after surgery. MATERIALS AND METHODS: This retrospective study included 392 patients with p-stage I non-small cell lung cancer with solid or part-solid nodules after curative lung resection in 2009-2010. Imbalances among the characteristics were adjusted using an inverse probability-weighted method based on propensity scoring. Multivariate Cox's regression analysis and the Kaplan-Meier method were used to determine independent risk factors for IPR. RESULTS: A total of 243 (62%) patients received TTNB, while 149 (38%) underwent an alternate, or no, diagnostic technique. IPR was significantly more frequent in the TTNB group (p=0.004), while total recurrence was similar between the groups (p=0.098). After applying the weighted model, diagnostic TTNB (hazard ratio [HR], 5.27; 95% confidence interval [CI], 1.49-18.69; p=0.010), microscopic visceral pleural invasion (HR, 2.76; 95% CI, 1.08-7.01; p=0.033) and microscopic lymphatic invasion (HR, 3.25; 95% CI, 1.30-8.10; p=0.012) were associated with an increased frequency of IPR. Among patients who received TTNB, microscopic lymphatic invasion was a risk factor for IPR (HR, 2.74; 95% CI, 1.10-6.79; p=0.030). CONCLUSIONS: The diagnostic TTNB procedure is associated with pleural recurrence but may be unrelated to overall recurrence-free survival in early lung cancer. Moreover, microscopic lymphatic invasion could be a risk factor for pleural recurrence. TTNB should be carefully considered before lung resection and close follow-up to detect if pleural recurrence is needed.

Relationship between Chronic Kidney Disease and Depression in Elderly Koreans Using the 2013 Korea National Health and Nutrition Examination Survey Data.

BACKGROUND: Depression is prevalent in patients with chronic kidney disease (CKD) and continues to increase in elderly adults. Therefore, the aim of our study was to examine the relationship between CKD and depression in older patients. METHODS: We conducted a cross-sectional study based on 2013 Korea National Health and Nutrition Examination Survey data. In total, data of 973 subjects aged ≥65 years were analyzed, and the estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. RESULTS: The prevalence of depression in older adults was 4.1% in men and 8.8% in women (P=0.004). The prevalence of depression did not differ according to CKD stage in women (normal eGFR and CKD stages 1 and 2 women, 41/474 [8.6%]) vs. CKD stages 3-5 women, 6/63 [9.5%]); however, the prevalence of depression in men with CKD stages 3-5 (8/83 [9.6%]) was significantly higher than in men with normal eGFR and CKD stage 1 and 2 (10/353 [2.8%], P=0.010). Multivariate logistic regression analysis showed that the odds ratio for depression in men with CKD stages 3-5 was 3.822 (95% confidence interval, 1.229 to 11.879) after adjusting for social status and chronic diseases (P=0.021). CONCLUSION: The prevalence of depression was higher in elderly women than in men, while the prevalence of depression increased in elderly men with CKD stages 3-5 and was almost equal to that of women. Therefore, elderly men with progressive renal function impairment should be counseled and monitored for psychological problems.

The application of the European heat wave of 2003 to Korean cities to analyze impacts on heat-related mortality.

The goal of this research is to transpose the unprecedented 2003 European excessive heat event to six Korean cities and to develop meteorological analogs for each. Since this heat episode is not a model but an actual event, we can use a plausible analog to assess the risk of increasing heat on these cities instead of an analog that is dependent on general circulation (GCM) modeling or the development of arbitrary scenarios. Initially, the 2003 summer meteorological conditions from Paris are characterized statistically and these characteristics are transferred to the Korean cites. Next, the new meteorological dataset for each Korean city is converted into a daily air mass calendar. We can then determine the frequency and character of "offensive" air masses in the Korean cities that are historically associated with elevated heat-related mortality. One unexpected result is the comparative severity of the very hot summer of 1994 in Korea, which actually eclipsed the 2003 analog. The persistence of the offensive air masses is considerably greater for the summer of 1994, as were dew point temperatures for a majority of the Korean cities. For all the Korean cities but one, the summer of 1994 is associated with more heat-related deaths than the analog summer, in some cases yielding a sixfold increase over deaths in an average summer. The Korean cities appear less sensitive to heat-related mortality problems during very hot summers than do large eastern and Midwestern US cities, possibly due to a lesser summer climate variation and efficient social services available during extreme heat episodes.