Because particulate matter (PM) and asthma are closely related, the prevalence of school absence among adolescents with asthma can be affected by the concentration of PM. We aimed to investigate the relationship between school absences due to asthma and the total number of days that the PM concentration exceeded the standard.

We used the data from the 16th Korea Youth Risk Behavior Survey and the PM levels of 17 metropolitan cities and provinces gathered from the AirKorea. Information on the characteristics of asthmatic adolescents and the prevalence of school absence was obtained using a questionnaire, while the PM levels based on the total number of days with poor and very poor PM grades were collected from the AirKorea website. Both χ² test and logistic regression analysis were performed using the weights presented in the original dataset.

In the case of particulate matter of 10 microns in diameter or smaller (PM₁₀), the odds ratio (OR) after adjusting for confounders (sex, school year, body mass index, smoking history, diagnosis of allergic rhinitis, diagnosis of atopic dermatitis and city size) was 1.07 (95% confidence interval [CI]: 1.01–1.13) for absents due to asthma when the total days of poor and very poor grades of PM₁₀ (81 μg/m³ or higher) increased by 1 day. In the analysis of particulate matter of 2.5 microns in diameter or smaller (PM_2.5), the OR after adjusting for confounders was 1.01 (95% CI: 1.00–1.03) for absents due to asthma when the total number of days with poor and very poor PM_2.5 grades (36 μg/m³ or higher) increased by 1 day.

A significant association was observed between the total number of days of poor and very poor PM₁₀ and PM_2.5 grades and school absence due to asthma; PM can cause asthma exacerbation and affect the academic life.

High concentrations of mercury intake from seafood are known to cause various side effects in humans, including on the nervous system. Various studies have reported the effects of mercury concentrations in humans; however, the association between dyslipidemia, a cardiovascular disease risk factor, and mercury remains controversial. Therefore, this study aimed to investigate the association between mercury accumulation and cholesterol concentrations in a Korean population.

We analyzed data of a sample of 3,228 respondents obtained from the Korean National Environmental Health Survey cycle 3, surveyed between 2015 and 2017, to determine how lipid profiles changed according to the blood mercury concentrations (BHg) and urine mercury concentrations (UHg). Multiple regression analysis was used to determine the effects of mercury concentrations among various factors affecting blood cholesterol levels.

The arithmetic mean (AM) of BHg was 2.91 (2.81–3.02) μg/L, and the geometric mean (GM) was 2.71 (2.59–2.85) μg/L. The AM of UHg was 0.52 (0.48–0.56) μg/L, and the GM was 0.35 (0.33–0.38) μg/L. Lipid profiles were more related to the BHg than to the UHg. Total cholesterol (total-C), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels increased significantly as BHg increased in males, and total-C, triglyceride, and LDL-C levels increased significantly in females. Multiple regression analysis indicated that BHg were significantly associated with total-C, HDL-C, and LDL-C levels.

We found an association between mercury exposure and the risk of dyslipidemia; however, further studies are required to elucidate a causal association.