The concentrations of PM2.5 and metallic elements were measured in Rayong during the dry season (November 2021 to April 2022). The mean PM2.5 concentration was 20.1 ± 10.9 µg/m³ (4.9–52.3 µg/m³). Moreover, the percentages of days when those PM2.5 concentrations exceeded the daily WHO and US-EPA NAAQS limit were 56.8% and 10.2%, respectively. However, the levels did not exceed 50 µg/m³, which is the limit of the 24 h standard defined by the PCD in Thailand. The dominant heavy metals and elements in PM2.5 samples were Cr, Cu, Fe, Mn, Pb, V, and Zn, which constituted 70%. In Rayong, the PCA results showed that industrial emissions (Cd, Cu, Fe, Mn, Pb, and Zn) and traffic emissions (As, Cd, Cr, K, and Ni) were the major sources of PM2.5-bound heavy metals. Exposure to toxic metals in PM2.5 through the inhalation pathway in Rayong obviously entails a high potential risk of cancer (>10⁻⁴) based on the total lung cancer risk (TCR_inh). It was found that the TCR_inh values of Cr for combined age groups were higher than 10⁻⁶, which implies a high cancer risk in Rayong.

Heavy metals are significant environmental pollutants that are recognized as posing a potential health hazard to human beings. We investigated the concentrations of the heavy metals As, Cd, Cr, Cu, Ni, Pb, and Zn in surface sediments collected from the Mae Chaem River in Chiang Mai, Thailand, during the dry season in 2021. The mean concentrations of heavy metals in sediments were, in decreasing order, Zn > Cr > As > Pb > Ni > Cu > Cd. The mean values of As, Cd, Cr, and Cu were determined to be 32.5 ± 18.3, 0.33 ± 0.07, 45.8 ± 11.9, and 21.9 ± 7.42 mg Kg⁻¹, respectively. These levels are higher than their standard levels in Thailand, namely 10.0, 0.16, 45.5, and 21.5 mg Kg⁻¹, respectively. Principal component analysis (PCA) revealed that the primary origins of heavy metal contamination are predominantly attributed to residential settlements and agricultural areas. The hazard quotient (HQ) was used to estimate the non-carcinogenic risk of exposure to heavy-metal-bound surface sediments for both children and adults. The results showed that the HQ values for both groups were less than 1.0 (HQ < 1.0), indicating no risk. Moreover, assessment of the long-term risk for ingestion of toxic metals indicated no risk (<10⁻⁶) based on the lifetime cancer risk (LCR). However, the LCR values of As and Cr were 5.3 × 10⁻⁶ and 2.5 × 10⁻⁶, respectively, demonstrating the most elevated LCR among the hazardous metals in terms of children’s exposure. Therefore, it is possible that children living in agricultural areas and participating in activities around the study area may be exposed to elevated concentrations of As and Cr.

This study aimed to examine trace element concentrations in indoor dust and evaluate health risks in child development centers in haze and industrial areas of Thailand from November 2023 to April 2024. The samples were extracted using a microwave oven and analyzed via ICP-OES. The finding indicated that the levels of As, Cr, Pb, V, Fe, Mn, and Zn in the dust from child development centers in the industrial area were significantly higher than those in the haze area (p < 0.05). The presence of trace element contaminants in indoor dust is indicative of anthropogenic sources. Cd and Zn in both areas have shown significantly elevated risks, according to the probable ecological risk factor. Source apportionment identified traffic, road dust, and biomass combustion as the principal sources of pollution in the haze area, while traffic and combustion activities were significant in the industrial area. Non-carcinogenic risk assessments for children exposed to As, Pb, Cu, and Cr revealed potential health risks (HI > 1). Furthermore, the total cancer risk (TCR) linked to As, Cr, and Ni is considered acceptable within the criteria of 10⁻⁶ to 10⁻⁴. However, long-term exposure may increase the risk of cancer in children.

Exposure to nitrogen dioxide (NO2) poses a danger to the health of many children all over the world especially children that attend schools in the vicinities of traffic roads and industries. This research study aims to assess the impacts of NO2 exposure on the health of the students. NO2 samples were collected by tube-type passive samplers. Moreover, the investigation of indoor NO2 exposure of students was associated with physical human health by using multiple logistic regressions. The results revealed that the indoor and outdoor NO2 concentrations in elementary schools were 9.0 ± 4.4 to 16.7 ± 2.7 μg/m3 and 8.2 ± 2.1 to 17.7 ± 6.7 μg/m3, respectively. However, indoor and outdoor values of NO2 were lower than the WHO standard of 40 μg/m3. Non-carcinogenic risk assessments of NO2 were carried out to help assess the health risks of students. It was found that the HQ of all those who studied in schools was less than 1, indicating no health risks. However, NO2 in classrooms can cause eye irritation (p-value = 0.007), pink eye/ allergic conjunctivitis (p-value = 0.012), runny nose (p-value = 0.020), sore throat (p-value = 0.038), wheeze (p-value = 0.022) and cough (p-value = 0.035). Therefore, children who spend time in classrooms close to heavy traffic and petrochemical plants might find themselves exposed to increased health risks.