The contribution of wildfire to PM2.5 trends in the USA.

Steady improvements in ambient air quality in the USA over the past several decades, in part a result of public policy1,2, have led to public health benefits1-4. However, recent trends in ambient concentrations of particulate matter with diameters less than 2.5 µm (PM2.5), a pollutant regulated under the Clean Air Act1, have stagnated or begun to reverse throughout much of the USA5. Here we use a combination of ground- and satellite-based air pollution data from 2000 to 2022 to quantify the contribution of wildfire smoke to these PM2.5 trends. We find that since at least 2016, wildfire smoke has influenced trends in average annual PM2.5 concentrations in nearly three-quarters of states in the contiguous USA, eroding about 25% of previous multi-decadal progress in reducing PM2.5 concentrations on average in those states, equivalent to 4 years of air quality progress, and more than 50% in many western states. Smoke influence on trends in the number of days with extreme PM2.5 concentrations is detectable by 2011, but the influence can be detected primarily in western and mid-western states. Wildfire-driven increases in ambient PM2.5 concentrations are unregulated under current air pollution law6 and, in the absence of further interventions, we show that the contribution of wildfire to regional and national air quality trends is likely to grow as the climate continues to warm.

Environmental forcing and policy synergy: A multidimensional approach in the governance of air pollution and carbon emission.

Policy synergies effectively contribute to the integrated management of air pollution and carbon emissions, which is crucial for safeguarding ecosystem stability and public health. This study uses the causal network model of Gaussian process regression to analyze the combined impacts of dynamic and static carbon emission reduction and air quality policies on carbon emissions and air quality. The causal effects of policy measures and their synergistic effects are also examined. The study results indicate: (1) There is significant geographical heterogeneity in the implementation of environmental policies and regional economic development, with the economically developed eastern coastal regions adopting more stringent carbon emission and air pollution control measures, while the western provinces adopt relatively lax environmental policies. (2) The synergistic effect of carbon emission reduction policies and air quality policies exists, and the two types of static policies are substitutable for managing carbon dioxide emissions and air pollution. (3) Policies' forced effect exists, where the exacerbation of environmental problems leads to the formation and implementation of policies. (4) The value added by the secondary industry is a key motivation for forming carbon emission reduction policies and air quality control policies. Additionally, the value added by the secondary industry directly impacts the incidence of respiratory diseases (e.g., tuberculosis). Finally, dynamic and synergistic policy recommendations are proposed based on the study's findings.

Digital economy and the synergistic governance of pollutants and carbon emissions: Facilitation or obstruction?

As an emerging force enabling high-quality economic development, digital economy (DE) still requires further investigation regarding its impact on synergistic governance of pollutants and carbon emissions (SGPCE). This study examines the impact of DE on SGPCE using two-way fixed effects model, intermediary effect model, and spatial Durbin model using provincial panel data from 2011 to 2020. The research reveals that: (1) DE has a significant promoting effect on SGPCE. (2) Enhancing the degree of green technology innovation is a crucial means of transmission for DE to propel SGPCE. (3) DE additionally exerts a constructive influence on SGPCE in adjacent regions, manifesting a spatial spillover effect. (4) Furthermore, DE demonstrates a notably heightened impact on SGPCE in the western region with respect to regional heterogeneity. Additionally, in the realm of dimension heterogeneity, the industrial digitization yields more favorable dividends for SGPCE compared to digital industrialization. The above conclusions provide novel insights and empirical evidence to validate the connection between DE and SGPCE. It also gives new policy recommendations for China to combat pollution prevention and climate warming under the wave of global digitization.

Government fiscal decentralization and haze and carbon reduction: Evidence from the fiscal Province-Managing-County reform.

Government governance reform is not only a vital motivation for high economic quality but also an important factor in stimulating the government's environmental governance responsibility. The article empirically examines the fiscal Province-Managing-County (PMC) pilot reform on the synergic governance of haze and carbon reduction and its mechanism. The results show that the policy helps to realize the synergic governance of haze and carbon reduction, and the reform of fiscal Province-Managing-County promotes regional haze and carbon reduction mainly through structural effect, innovation effect, and fiscal expenditure responsibility effect. The heterogeneity analysis shows that the policy has an asymmetric effect on haze and carbon reduction under different administrative structures, economic structures and levels of government intervention. Further analysis shows a policy linkage effect between this policy and the Green Fiscal Policy. The policy has the situation of blood-sucking in the provincial capital city and leads to an increase in financial funds. The above results prove that the policy can help to realize haze and carbon reduction and provide practical ideas for the further expansion of the policy. At the same time, it provides the direction for the local government to realize the double-carbon goal.

Assessing the impact of environmental regulations on environmental performance in Chinese cities: A spatial Stochastic Frontier Model with endogeneity analysis.

The Chinese government has implemented environmental regulations to address the deterioration of air quality associated with rapid industrialization. However, there is no consensus on whether environmental regulations are beneficial to environmental performance. The technical challenges related to endogeneity and spatial correlation may bias the estimation of the emission reduction effect of regulations. In this study, we comprehensively evaluate the environmental performance of sulfur dioxide regulations in Chinese cities using a novel stochastic frontier model that introduces the single control function to correct estimation errors caused by spatial spillovers and endogeneity. Our analysis emphasizes that insufficient resolution of endogeneity or spatial spillovers may lead to underestimation or neglect of the environmental performance improvements achieved by these regulations. On the contrary, our revised research results indicate that regulations aimed at reducing sulfur dioxide emissions not only successfully control sulfur dioxide emissions, but also have a positive impact on reducing carbon emissions. In addition, we conduct in-depth research on the mechanisms by which environmental regulations improve performance by stimulating green technology innovation and promoting industrial structure upgrading. Based on our research findings, we propose policy recommendations to establish a city cooperation mechanism of technology exchange to achieve synergistic emission reduction and strengthen regional factor circulation.

How informal environmental regulations constrain carbon dioxide emissions under pollution control and carbon reduction: Evidence from China.

Exploring whether informal environmental regulations (INER) can achieve carbon reduction in the context of pollution reduction and carbon reduction, as well as how to achieve carbon reduction, can help solve the dual failures of the market and government in environmental protection. Based on the polycentric governance theory and considering the characteristics of social subject environmental participation, the Stackelberg game is used to demonstrate the impact mechanism of INER on CO2. In addition, using the panel data of China's 30 provinces from 2003 to 2018, this paper validates the effectiveness of INER by Pooled Ordinary Least Square (POLS) and threshold panel model. Then, the mediating effect model is used to test the mechanism of INER's effect on carbon reduction. The results show that corruption is not conducive to CO2 reduction. The reduction effect of INER on CO2 exhibits heterogeneity with changes in other non-greenhouse gas pollutants. While INER effectively reduces local corruption, its more substantial indirect impact on CO2 reduction is prominent when levels of other pollutants are lower. Comparative analysis reveals that there are still biased governance behaviors to cope with INER's pressure in some regions nowadays. The findings show that for countries facing the dual task of pollution control and carbon reduction, the key to leveraging the supervisory role of INER should be focused on mitigating information asymmetry caused by the characteristics of CO2. Therefore, in the process of environmental protection, the public environmental participation system should be improved, and the process of disclosing polluters' carbon information should be accelerated.

Governance effects of pollution reduction and carbon mitigation of carbon emission trading policy in China.

China's carbon emission trading policy plays a crucial role in achieving both its "3060" dual carbon objectives and the United Nations Sustainable Development Goal 13 (SDG 13) on climate action. The policy's effectiveness in reducing pollution and mitigating carbon emissions holds significant importance. This paper investigated whether China's carbon emission trading policy affects pollution reduction (PM2.5 and SO2) and carbon mitigation (CO2) in pilot regions, using panel data from 30 provinces and municipalities in China from 2005 to 2019 and employing a multi-period difference-in-differences (DID) model. Furthermore, it analyzed the heterogeneity of carbon market mechanisms and regional variations. Finally, it examined the governance pathways for pollution reduction and carbon mitigation from a holistic perspective. The results indicate that: (1) China's carbon emission trading policy has reduced CO2 emissions by 18% and SO2 emissions by 36% in pilot areas, with an immediate impact on the "carbon mitigation" effect, while the "pollution reduction" effect exhibits a time lag. (2) Higher carbon trading prices lead to stronger "carbon mitigation" effect, and larger carbon market scales are associated with greater "pollution reduction" effects on PM2.5. Governance effects on pollution reduction and carbon mitigation vary among pilot regions: Carbon markets of Beijing, Chongqing, Shanghai, and Tianjin show significant governance effects in both "pollution reduction" and "carbon mitigation", whereas Guangdong's carbon market exhibits only a "pollution reduction" effect, and Hubei's carbon market demonstrates only a "carbon mitigation" effect. (3) Currently, China's carbon emission trading policy achieves pollution reduction and carbon mitigation through "process management" and "end-of-pipe treatment". This study could provide empirical insights and policy implications for pollution reduction and carbon mitigation, as well as for the development of China's carbon emission trading market.

Does "National Civilized City" policy mitigate air pollution in China? A spatial Durbin difference-in-differences analysis.

"National Civilized City" (NCC) is regarded as China's highest honorary title and most valuable city brand. To win and maintain the "golden city" title, municipal governments must pay close attention to various key appraisal indicators, mainly environmental ones. In this study we verify whether cities with the title are more likely to mitigate SO2 pollution. We adopt the spatial Durbin difference-in-differences (DID) model and use panel data of 283 Chinese cities from 2003 to 2018 to analyze the local (direct) and spillover effects (indirect) of the NCC policy on SO2 pollution. We find that SO2 pollution in Chinese cities is not randomly distributed in geography, suggesting the existence of spatial spillovers and possible biased estimates. Our study treats the NCC policy as a quasi-experiment and incorporates spatial spillovers of NCC policy into a classical DID model to verify this assumption. Our findings show: (1) The spatial distribution of SO2 pollution represents strong spatial spillovers, with the most highly polluted regions mainly situated in the North China Plain. (2) The Moran's I test results confirms significant spatial autocorrelation. (3) Results of the spatial Durbin DID models reveal that the civilized cities have indeed significantly mitigated SO2 pollution, indicating that cities with the honorary title are acutely aware of the environment in their bid to maintain the golden city brand. As importantly, we notice that the spatial DID term is also significant and negative, implying that neighboring civilized cities have also mitigated their own SO2 pollution. Due to demonstration and competition effects, neighboring cities that won the title ostensibly motivates local officials to adopt stringent policies and measures for lowering SO2 pollution and protecting the environment in competition for the golden title. The spatial autoregressive coefficient was significant and positive, indicating that SO2 pollution of local cities has been deeply affected by neighbors. A series of robustness check tests also confirms our conclusions. Policy recommendations based on the findings for protecting the environment and promoting sustainable development are proposed.

Narrowing feedstock exemptions under the Montreal Protocol has multiple environmental benefits.

The Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) can be further strengthened to control ozone-depleting substances and hydrofluorocarbons used as feedstocks to provide additional protection of the stratospheric ozone layer and the climate system while also mitigating plastics pollution. The feedstock exemptions were premised on the assumption that feedstocks presented an insignificant threat to the environment; experience has shown that this is incorrect. Through its adjustment procedures, the Montreal Protocol can narrow the scope of feedstock exemptions to reduce inadvertent and unauthorized emissions while continuing to exempt production of feedstocks for time-limited, essential uses. This upstream approach can be an effective and efficient complement to other efforts to reduce plastic pollution. Existing mechanisms in the Montreal Protocol such as the Assessment Panels and national implementation strategies can guide the choice of environmentally superior substitutes for feedstock-derived plastics. This paper provides a framework for policy makers, industries, and civil society to consider how stronger actions under the Montreal Protocol can complement other chemical and environmental treaties.

The environmental consequences of national Audit governance: An analysis based on county-level data in China.

Recent years have witnessed growing public concern over air pollution in China, posing a challenge to the government's environmental management efforts. Empirical evidence indicates that the digital economy contributes to mitigating environmental pollution. Given that national audits are a crucial part of the national oversight system and considering the significant role of digital technology in audit governance, it is relevant to explore how the digital economy can support national audits in enhancing China's environmental quality. This study investigates the environmental impact of national audit governance, utilizing a dataset from 1540 counties in China spanning from 2005 to 2018. The findings reveal that effective national audits contribute to reducing haze pollution (HP) levels, with the digital economy playing a moderating role. The results also demonstrate heterogeneity; national audits are particularly effective in regions characterized by high urbanization rates, severe HP, and stringent environmental regulations. The mechanism analysis suggests that industrial transformation and enhanced government governance are the key mechanisms through which national audits reduce regional HP. Additionally, reforming the audit management system can amplify the effects of national audits on reducing HP.

Interstate Air Pollution Governance in the United States: Exploring Clean Air Act Section 126.

Air pollution is arguably the most pressing human health concern today, accounting for approximately 7-9 million premature deaths worldwide. In the United States, more than 40% of early deaths caused by air pollution are assessed to be caused by emissions produced by neighboring states. This article examines one of the governance mechanisms used by the U.S. to address this issue: section 126 of the Clean Air Act. Critical factors including case length, evidence used, and case outcome are compiled for the population of section 126 petitions submitted from 2000-2022. This evidence is assessed using comparative case analysis. The findings reinforce two issues with the petition process already identified in the literature-the use of cost as a proxy for significance and the excessive and unclear burden of proof placed on downwind states-adding texture to the latter issue by examining the modeling techniques used by downwind states. This analysis identifies lengthy response timelines as an additional issue and calls to attention the infrequency with which the EPA has formally accepted petitions. Collectively, these issues increase the cost, complexity, and unpredictability of filing a section 126 petition.

On the use of group performance and rights for environmental protection and resource management.

Environmental and natural resource (ENR) policies that focus on group outcomes are common but have received relatively less attention from economists than policies based on individual behavior. Existing research tends to focus on particular contexts, such as water or air quality, fisheries, or land use. This paper discusses unifying themes of group performance policies, along with their advantages and disadvantages. We discuss a range of specific policy instruments, including group-based taxes, subsidies, and fixed penalties. We show how, in principle, group-based policies can be designed to achieve efficient provision of group-level environmental performance; however, in some cases, group policies can lead to suboptimal outcomes. We discuss the incentives for collaboration that can arise when regulators impose group performance policies, and the role that it can play in promoting efficient outcomes. We argue that the success of group-based policies will depend both on how the policy is designed (i.e., the external rewards and penalties) and on how the group operates. This implies potential complementarities between "top-down" regulatory interventions based on group performance and "bottom-up" within-group incentives for self-governance. Our discussion suggests that group performance policies should play a more prominent role in the suite of policy instruments considered by scholars and policymakers concerned with ENR management.

Mercury source changes and food web shifts alter contamination signatures of predatory fish from Lake Michigan.

To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary to identify food web influences. Through combined Hg, C, and N stable isotopic analyses, we were able to differentiate between a shift in Hg sources to fish and periods when energetic transitions (from dreissenid mussels) led to the assimilation of contrasting Hg pools (2000 to present). In the late 1980s, lake trout δ202Hg increased (0.4‰) from regulatory reductions in regional Hg emissions. After 2000, C and N isotopes ratios revealed altered food web pathways, resulting in a benthic energetic shift and changes to Hg bioaccumulation. Continued increases in δ202Hg indicate fish are responding to several United States mercury emission mitigation strategies that were initiated circa 1990 and continued through the 2011 promulgation of the Mercury and Air Toxics Standards rule. Unlike archives of sediments, this fish archive tracks Hg sources susceptible to bioaccumulation in Great Lakes fisheries. Analysis reveals that trends in fish Hg concentrations can be substantially affected by shifts in trophic structure and dietary preferences initiated by invasive species in the Great Lakes. This does not diminish the benefits of declining emissions over this period, as fish Hg concentrations would have been higher without these actions.

The Potential Effects of Policy-driven Air Pollution Interventions on Childhood Lung Development.

Rationale: Although elevated air pollution exposure impairs lung-function development in childhood, it remains a challenge to use this information to estimate the potential public health benefits of air pollution interventions in exposed populations.Objectives: Apply G-computation to estimate hypothetical effects of several realistic scenarios for future air pollution reductions on lung growth.Methods: Mixed-effects linear regression was used to estimate FEV1 and FVC from age 11 to 15 years in 2,120 adolescents across 3 cohorts (1993-2001, 1997-2004, and 2007-2011). Models included regional pollutants (nitrogen dioxide [NO2] or particulate matter with an aerodynamic diameter ≤2.5 µm [PM2.5]) and other important covariates. Using G-computation, a causal inference-based method, we then estimated changes in mean lung growth in our population for hypothetical interventions on either NO2 or PM2.5. Confidence intervals (CIs) were computed by bootstrapping (N = 1,000).Measurements and Main Results: Compared with the effects of exposure from observed NO2 concentrations during the study period, had communities remained at 1994 to 1997 NO2 levels, FEV1 and FVC growth were estimated to have been reduced by 2.7% (95% CI, -3.6 to -1.8) and 4.2% (95% CI, -5.2 to -3.4), respectively. If NO2 concentrations had been reduced by 30%, we estimated a 4.4% increase in FEV1 growth (95% CI, 2.8-5.9) and a 7.1% increase in FVC growth (95% CI, 5.7-8.6). Comparable results were observed for PM2.5 interventions.Conclusions: We estimated that substantial increases in lung function would occur as a result of interventions that reduce NO2 or PM2.5 concentrations. These findings provide a quantification of potential health benefits of air quality improvement.

Health effects of banning beehive coke ovens and implementation of the ban in China.

Environmental legislation and proper implementation are critical in environmental protection. In the past, beehive coke ovens (BCOs) were popular in China, resulting in enormous emissions of benzo[a]pyrene (BaP), a common indicator of carcinogenic polycyclic aromatic hydrocarbons. BCOs were banned by the Coal Law in 1996. Although BCO numbers have declined since the ban, they were not eliminated until 2011 due to poor implementation. Here, we present the results of a quantitative evaluation of the health effects of historical BCO operation, the health benefits of the ban, and the adverse impacts of the poor implementation of the ban. With only limited official statistics available, historical and geospatial data about BCOs were reconstructed based on satellite images. Emission inventories of BaP from BCOs were compiled and used to model atmospheric transport, nonoccupational population exposure, and induced lung cancer risk. We demonstrated that more than 20% of the BaP in ambient air was from BCOs in the peak year. The cumulative nonoccupational excess lung cancer cases associated with BaP from BCOs was 3,500 (±1,500) from 1982 to 2015. If there was no ban, the cases would be as high as 9,290 (±4,300), indicating the significant health benefits of the Coal Law. On the other hand, if the ban had been fully implemented immediately after the law was enforced in 1996, the cumulative cases would be 1,500 (±620), showing the importance of implementing the law.

Estimating Causal Effects of Particulate Matter Regulation on Mortality.

BACKGROUND: Estimating the causal effect of pollution on human health is integral for evaluating returns to pollution regulation, yet separating out confounding factors remains a perennial challenge. METHODS: We use a quasi-experimental design to investigate the causal relationship between regulation of particulate matter smaller than 2.5 micrograms per cubic meter (PM2.5) and mortality among those 65 years of age and older. We exploit regulatory changes in the Clean Air Act Amendments (CAAA). Regulation in 2005 impacted areas of the United States differentially based on pre-regulation air quality levels for PM2.5. We use county-level mortality data, extracted from claims data managed by the Centers for Medicare & Medicaid Services, merged to county-level average PM2.5 readings and attainment status as classified by the Environmental Protection Agency. RESULTS: Based on estimates from log-linear difference-in-differences models, our results indicate after the CAAA designation for PM2.5 in 2005, PM2.5 levels decreased 1.59 micrograms per cubic meter (95% CI = 1.39, 1.80) and mortality rates among those 65 and older decreased by 0.93% (95% CI = 0.10%, 1.77%) in nonattainment counties, relative to attainment ones. Results are robust to a series of alternate models, including nearest-neighbor matching based on propensity score estimates. CONCLUSION: This analysis suggests large health returns to the 2005 PM2.5 designations, and provides evidence of a causal association between pollution and mortality among the Medicare population.