Due to the rapid increase of population density and automobile vehicle numbers in mega-cities, large underground garages have become universal supporting facilities to meet the demand for parking spaces in the recently-built commercial complexes and high-rise residential communities. Natural ventilation was insufficient to discharge vehicle-induced pollutants out of the enclosed underground spaces, which could pose a potential threat to people’s health. This study aims to determine the spatial and temporal distribution characteristics of pollutants concentration and the health risk of underground parking garages (UPGs)’ staff and users. Field measurements were conducted on the air pollutants concentrations and the users’ exposure characteristics in 11 commercial UPGs and three high-rise residential UPGs with natural ventilation in Xi’an. The pollutants concentrations were higher in the afternoon and morning of commercial and high-rise residential UPGs. In general, the particulate matters (PM_2.5 and PM₁₀), HCHO, TVOC and BTEX (benzene, toluene, ethylbenzene and xylenes) concentrations in commercial and residential UPGs were 0.069/0.067 mg/m³, 0.12/0.097 mg/m³, 0.014/0.017 mg/m³, 1.8/1.8 mg/m³, 0.056/0.10 mg/m³, 0.19/0.29 mg/m³ and 0.41/0.49 mg/m³, respectively. TVOC and BTEX concentrations in UPGs significantly correlated with traffic volume ( p < 0.01). In different groups, the entropy values of carcinogenic and non-carcinogenic risks were: staffs > children travelling with adults > adults. In particular, occupational long-term (employee) exposure could lead to both carcinogenic and non-carcinogenic risks.

China is faced with significant challenges in simultaneously promoting rural development and reducing carbon emissions. However, the issue of quantifying and addressing carbon emissions in rural areas has not been adequately addressed. Accurately quantifying these emissions is crucial for developing effective strategies to reduce carbon output. In this study, the historical evolution and spatial distribution of rural carbon emissions in northwestern China from 2006 to 2019 were evaluated across five key sectors: residential energy consumption, agricultural machinery, solid waste management, planting practices, and breeding industry activities. During this period, total carbon emissions in rural areas of northwest China steadily increased from 60.15Mt to 83.49Mt at an annual growth rate of 2.55%. Given the complex interplay between economic and social factors driving these changes, the future trajectory of rural carbon emissions remains uncertain. To analyze the underlying drivers behind regional variations in carbon emissions over time, we constructed an LMDI model which revealed that economic growth primarily contributed to regional increases in carbon output. Furthermore, due to a remarkable annual growth rate of 35.17% in renewable energy generation (such as photovoltaic and wind power), it can be inferred that if renewable electricity were included within our calculations for carbon emission statistics, northwest China’s rural areas achieved a state of being effectively ‘carbon-neutral’ by 2019 solely from a production-based perspective.

Ecological vulnerability zoning research is an important basis for taking targeted regional ecological environment restoration and governance measures. This study analyzes the ecological vulnerability pattern and trend in the National Energy and Chemical Base (NECB) in the typical region of the Loess Plateau using GIS (Geographic Information System) data and the fuzzy analytic hierarchy process (FAHP) approach. Based on the human activity–natural environment factor index system, 13 factors representing human activities, socioeconomics, meteorology, soil and topography are selected to build an ecological vulnerability index (EVI) system in the NECB region, which aims at identifying the regional features of eco-environment and major environmental problems in the Loess Plateau. By calculating ecological vulnerability zoning, a model of ecological vulnerability trend change is constructed to quantitatively study the overall temporal and spatial variation of ecological vulnerability. The results indicate that the medium and heavy levels of ecological vulnerability index were mostly distributed in the areas with developed energy and chemical industries, and the slight and light levels were distributed in the southern area and developed agricultural regions. A comprehensive ecological vulnerability index had a score of 2.3207 in 2015 and 2.441 in 2000, indicating that the ecological security gradually improved. Nevertheless, highly intense human activities accelerated the degradation of regional eco-environment in recent years.