Health Benefits in California of Strengthening the Fine Particulate Matter Standards

Global Changes in Ischemic Stroke Burden Attributable to Ambient PM2.5: Trends From 1990 to 2020 and Projections to 2050

BACKGROUND AND OBJECTIVES

Ischemic stroke (IS) is a leading cause of disability and mortality worldwide, with ambient fine particulate matter (PM2.5) exposure being a significant modifiable risk factor. While PM2.5 concentrations have declined in some regions, global assessments examining how these changes affect the IS burden remain limited. The aim of this study was to quantify changes in IS burden attributable to PM2.5 from 1990 to 2020 and project future trends to 2050.

METHODS

We used data from the 2021 Global Burden of Disease study, including population estimates, IS incidence rates, and PM2.5 concentrations, for 204 countries and World Bank regions. The Environmental Benefits Mapping and Analysis Program algorithm was applied to estimate IS cases attributable to PM2.5. Future projections were calculated using an autoregressive integrated moving average model.

RESULTS

Between 1990 and 2020, global PM2.5 concentrations decreased by 8.18 μg/m3. This reduction was associated with approximately 920,245 avoided IS cases, equivalent to 12.11% of the global IS incidence in 2020. The East Asia and Pacific region experienced the greatest benefit, with 699,218 IS cases avoided (19.09% of the region's IS incidence in 2020). By 2050, PM2.5 concentrations are projected to decline by 33.64 μg/m3 relative to 1990, potentially preventing an additional 6,004,854 IS cases. However, significant disparities persist, particularly in low-income regions where PM2.5 exposure and limited health care infrastructure continue to pose challenges.

DISCUSSION

Our findings highlight the substantial public health benefits of PM2.5 reductions in mitigating the IS burden. While high-income regions have seen substantial gains due to stringent air quality regulations, low-income regions remain disproportionately affected. Addressing these disparities requires targeted pollution control policies and equitable health care resource allocation. Sustained efforts in air quality management are critical to reducing the global IS burden and improving health outcomes, particularly in vulnerable populations.

Decarbonization will lead to more equitable air quality in California

Air quality associated public health co-benefit may emerge from climate and energy policies aimed at reducing greenhouse gas (GHG) emissions. However, the distribution of these co-benefits has not been carefully studied, despite the opportunity to tailor mitigation efforts so they achieve maximum benefits within socially and economically disadvantaged communities (DACs). Here, we quantify such health co-benefits from different long-term, low-carbon scenarios in California and their distribution in the context of social vulnerability. The magnitude and distribution of health benefits, including within impacted communities, is found to varies among scenarios which reduce economy wide GHG emissions by 80% in 2050 depending on the technology- and fuel-switching decisions in individual end-use sectors. The building electrification focused decarbonization strategy achieves ~15% greater total health benefits than the truck electrification focused strategy which uses renewable fuels to meet building demands. Conversely, the enhanced electrification of the truck sector is shown to benefit DACs more effectively. Such tradeoffs highlight the importance of considering environmental justice implications in the development of climate mitigation planning.

Air quality is found to be more equitable through two salient decarbonization pathways for California in 2050 with the relative justice of decarbonization scenarios quantified at the neighborhood level and the tradeoffs between pathways evaluated.