We present a new divergence method to estimated methane (CH₄) emissions from satellite observed mean mixing ratio of methane (XCH₄) by deriving the regional enhancement of XCH₄ in the Planetary Boundary Layer (PBL). The applicability is proven by comparing the estimated emissions with its known emission inventory from a 3‐month GEOS‐Chem simulation. When applied to TROPOspheric Monitoring Instrument observations, sources from well‐known oil/gas production areas, livestock farms and wetlands in Texas become clearly visible in the emission maps. The calculated yearly averaged total CH₄ emission over the Permian Basin is 3.06 (2.82, 3.78) Tg a⁻¹ for 2019, which is consistent with previous studies and double that of EDGAR v4.3.2 for 2012. Sensitivity tests on PBL heights, on the derived regional background and on wind speeds suggest our divergence method is quite robust. It is also a fast and simple method to estimate the CH₄ emissions globally.

Cities are at the front line of combating environmental pollution and climate change, thus support from cities is crucial for successful enforcement of environmental policy. To mitigate environmental problems, China introduced at provincial level the Environmental Protection Tax Law in 2018. Yet the resulting economic burden on households in different cities with significantly different affluence levels remains unknown. The extent of the economic impacts is likely to affect cities’ support and public acceptability. This study quantifies the economic burden of urban households from taxation of fine particle pollution (PM_2.5) for 200 cities nationwide from a ‘consumer’ perspective, accounting for PM_2.5 and precursor emissions along the national supply chain. Calculations are based on a multi-regional input–output analysis, the official tax calculation method and urban household consumption data from China’s statistical yearbooks. We find that the current taxation method intensifies economic inequality between cities nationally and within each province, with some of the richest cities having lower tax intensities than some of the poorest. This is due to the fact that taxes are collected based on tax rates of producing regions rather than consuming regions, that cities with very different affluence levels within a province bear the same tax rate, and that emission intensities in several less affluent cities are relatively high. If the tax could be levied based on tax rates of each city where the consumer lives, with tax rates determined based on cities’ affluence levels and with tax revenues used to support emission control, inter-city economic inequality could be reduced. Our work provides quantitative evidence to improve the environmental tax and can serve as the knowledge base for coordinated inter-city policy.

Ozone pollution is a major transboundary threat to global health. Systematic improvement of mitigation strategy for transboundary ozone requires a socioeconomic understanding of historical lessons in countries at different affluence levels. Here, we explore the changes in transboundary ozone related premature deaths over 1951–2019 driven by anthropogenic emissions of four country groups categorized by income level. By integrating global emission datasets, a chemical transport model (GEOS-Chem), in situ ozone measurements worldwide and an ozone exposure-response model, we find that mortality caused by transboundary anthropogenic ozone increases by 27 times from 1951 to 2019, and on average contributes about 27% of global anthropogenic ozone related deaths. All groups exert and suffer from substantial transboundary ozone related mortality. The high-income and upper middle groups have each experienced an inverted U-shaped relationship between its affluence and per-million-people contribution to mortality caused by transboundary ozone, with the turning point around 23 000 USD and 6300 USD, respectively. The lower middle group has gradually matched the growth pathway of the upper middle group with a turning point less clear. Concerted efforts to ensure early turning points in less affluent countries will have considerable global health benefits.