Estimate Gaps of Montreal Protocol-Regulated Potent Greenhouse Gas HFC-152a Emissions in China Have Been Explained.

1,1-Difluoroethane (HFC-152a) is a hydrofluorocarbon regulated by the Montreal Protocol, and its emissions in China are of concern as China will regulate HFC-152a in 2024. However, no observation-inferred top-down estimates were undertaken after 2017, and substantial gaps existed among previous estimates of China's HFC-152a emissions. Using the atmospheric observations and inverse modeling, this study reveals China's HFC-152a emissions of 9.4 ± 1.7 Gg/yr (gigagrams per year), 10.6 ± 1.8 Gg/yr, and 9.7 ± 1.5 Gg/yr in 2018, 2019, and 2020, respectively. In addition, we display an overall increasing trend during 2011-2020, which is in contrast to the decreasing and steady trend reported by the Emission Database for Global Atmospheric Research (EDGAR) and the Chinese government, respectively. Subsequently, we establish a comprehensive bottom-up emission inventory matching with top-down estimates and thus succeed in explaining the gaps among previous estimates. Furthermore, the contribution of China's emissions to global HFC-152a emission growth increased from 15% during 2001-2010 to >100% during 2011-2020. An emission projection based on our improved inventory shows that the Kigali Amendment (KA) would assist in avoiding 1535.6-4710.6 Gg (251.8-772.5 Tg CO2-eq) HFC-152a emissions during 2024-2100. Our findings indicate relatively accurate China's HFC-152a emissions and provide scientific support for addressing climate change and implementing the KA.

Structural characteristics and drivers of greenhouse gas emissions at county-level and long-time scales: A case study of the Anji County, China.

To achieve carbon neutrality, the Chinese government needs to gain a comprehensive understanding of the sources and drivers of greenhouse gas (GHG) emissions, particularly at the county level. Anji County in eastern China is a typical example of an industrial transformation from quarrying to a low-carbon economy. This study analyzed the decoupling types and structural characteristics of GHG emissions and the driving factors of carbon dioxide (CO2) emissions in the Anji from 2006 to 2019, and explored the differences between county-level and provincial-level or city-level results. It was observed that energy-related activities are the main source of GHG emissions in Anji and that economic development is the driving factor behind the increasing CO2 emissions. However, industrial transformation and upgradation coupled with the alternative use of clean energy limit the growth of GHG emissions. This study details the GHG emissions of county during the industrial transformation stage and provides corresponding policy recommendations for county governments.

Mitigation of Fully Fluorinated Greenhouse Gas Emissions in China and Implications for Climate Change Mitigation.

Fully fluorinated greenhouse gases (FFGHGs), including sulfur hexafluoride (SF6), nitrogen trifluoride (NF3), and perfluorocarbons (PFCs), have drawn attention because they have long atmospheric lifetimes (up to thousands of years) and high global warming potential. Targeting SF6, NF3, and four PFCs (CF4, C2F6, C3F8, and c-C4F8), this study projects future FFGHG emission patterns in China, explores their mitigation potential, and evaluates the effects of FFGHG emission reduction on the achievement of the country's carbon neutrality goal and climate change. FFGHG emissions are expected to increase consistently, ranging from 506 to 1356 Mt CO2-eq yr-1 in 2060 under the business-as-usual (BAU) scenario. If mitigation strategies are sufficiently employed, FFGHG emissions under three mitigation scenarios: Technologically Feasible 2030, Technologically Feasible 2050, and Technologically Feasible 2060, will eventually decrease to approximately 49-78, 70-110, and 98-164 Mt CO2-eq yr-1 in 2060, respectively, compared to the BAU scenario. Extensive implementation of FFGHG emission mitigation technologies will curb temperature rise by 0.008-0.013 °C under the slowest mitigation scenario, compared to 0.013-0.026 °C under the BAU scenario. Well-coordinated policies and reforms on FFGHG emission mitigation are recommended to prevent potential adverse effects on the climate to a certain extent.

Indoor Volatile Organic Compounds: Concentration Characteristics and Health Risk Analysis on a University Campus.

Volatile organic compounds (VOCs) are major indoor air pollutants that contain several toxic substances. However, there are few studies on health risk assessments of indoor VOCs in China. This study aimed to determine the concentration characteristics of VOCs on college campuses by collecting VOC samples from different locations on campus during different seasons combined with the exposure times of college students in each location obtained from a questionnaire survey to assess the possible health risks. The highest total VOC concentration (254 ± 101 µg/m3) was in the dormitory. The seasonal variation of TVOC concentrations was related to the variation of emission sources in addition to temperature. Health risk assessments of VOCs were evaluated using non-carcinogenic and carcinogenic risk values, represented by hazard quotient (HQ) and lifetime cancer risk (LCR), respectively. The non-carcinogenic risks at all sampling sites were within the safe range (HQ < 1). Dormitories had the highest carcinogenic risk, whereas the carcinogenic risk in the other three places was low (with LCR < 1.0 × 10-6). Moreover, 1,2-dichloroethane was identified as a possible carcinogenic risk substance in the dormitory due to its high LCR (1.95 × 10-6). This study provides basic data on health risks in different locations on campus and a basis for formulating measures to improve people's living environments.