Research on the outdoor thermal comfort of children in Hangzhou and Its influence on the underlying surface reflectance.

The outdoor thermal comfort (OTC) of children is more specific than that of adults, and the complex influence of outdoor activity spaces on children's thermal comfort warrants further investigation. To investigate the outdoor thermal comfort baseline (OTCB) of children in Hangzhou and explore the thermal impact of outdoor surfaces on children, a survey was conducted in six typical outdoor activity spaces in Hangzhou, China, during spring and summer utilizing physical measurements, questionnaire surveys, and the universal thermal climate index (UTCI). This study analyzed the differences in thermal perception among children in Hangzhou in different seasons, their OTCB, and the impact of surface reflectance (Rs) on children's OTC. The results indicated the following: 1) In spring, children in Hangzhou generally felt comfortable, but their discomfort with heat noticeably increased in summer. 2) The neutral UTCIs (NUTCIs) for Hangzhou children were 11.6 °C (spring) and 27.7 °C (summer), and the NUTCI ranges (NUTCIRs) were 9.7-17.5 °C (spring) and 25.7-30.0 °C (summer); additionally, the thermal acceptability ranges (TARs) were 13.2-25.2 °C (spring) and 11.8-34.8 °C (summer). 3) A high Rs made children feel more uncomfortable with heat, which was primarily due to the space's total shortwave and longwave radiation, which peaked between 14:00 and 15:00. 4) Based on the research findings, corresponding bioclimatic design strategies were proposed. Recommendations include using high Rs underlays with shading, composite underlays, or the future adoption of thermochromic coatings. Keeping permeable underlays moist is essential for activating their cooling mechanisms. Fundamental safety measures are imperative. This study provides valuable data for urban planners and landscape designers to create public spaces suitable for children's outdoor activities, contributing to a harmonious and unified living environment.

Characterization, Sources and Excessive Cancer Risk of PM2.5-Bound Polycyclic Aromatic Hydrocarbons in Different Green Spaces in Lin'an, Hangzhou, China.

PM2.5 samples were collected from residential, commercial, plaza and public green spaces in Lin'an, Hangzhou, in spring (March and April) and winter (February and December) in 2017. PAHs were detected by gas chromatography-mass spectrometry (GC-MS), and their sources were identified using the diagnostic ratio (DR) and principal component analysis-multiple linear regression (PCA-MLR). The average PAH concentration in winter was 1.3 times that in spring (p < 0.01). The PAH concentrations in the green spaces decreased as commercial > residential > plaza > public green space (p < 0.05). The sources of PAHs were vehicle emissions and coal combustion pollution transported by northern Chinese air masses. Slightly higher excessive cancer risks were determined in the commercial and residential green spaces than in the plaza and public green spaces. Green coverage, pedestrian volume, traffic flow and building density greatly influenced the decrease in the PAH concentration in the green spaces. Among the 4 types of green spaces, public green space had the most ecological benefits and should be fully utilized in urban green space planning to improve public health in urban spaces.

The relationship between particulate matter retention capacity and leaf surface micromorphology of ten tree species in Hangzhou, China.

Atmospheric particulate matter (PM) is one of the main environmental air pollutants, but it can be retained and adsorbed by plants. To systematically and comprehensively conduct qualitative and quantitative research on the relationship between the leaf PM retention ability and the microstructure of leaf surfaces, this study evaluated the PM retention abilities of ten common tree species (1860 leaf pieces in total) in the greenbelts around the Lin'an toll station of the Hang-Rui Expressway in Hangzhou, China, in October 2019. The leaf surface roughness and contact angle were measured with confocal laser scanning microscopy and a contact angle measuring instrument. Scanning electron microscopy was applied to collect data on the stomata and groove morphology. The PM retention ability of the leaves was assessed by quantifying the PM mass and number density on the leaves. The results revealed that Platanus acerifolia and Sapindus mukorossi had a strong ability to retain particulates of different sizes. The mass of the retained PM2.5 on their leaves accounted for the lowest proportion (mean: 8.12%) among the total retained particulate mass, but the number density of the retained PM2.5 accounted for the highest proportion (mean: 97.49%) among the total number density. A significant negative correlation between the PM2.5 mass and the groove width on the adaxial surface (R2 = 0.746, P < 0.05) and a significant positive correlation between the roughness and the PM number density on the adaxial surface (R2 = 0.702, P < 0.01) were observed. No obvious correlations were found among the groove width, roughness and number density of the retained PM on the abaxial surface. Leaf surfaces with dense and narrow grooves, strip-like projections, high roughness and high wettability had strong retention abilities. This study can provide a theoretical reference for selecting plants with strong PM retention ability for green urban garden design.