Changes of Long-Term Exposure to Ultrafine Particles From 2010 to 2019 in High Income Countries in Relation to Cardiovascular Diseases.

Ultrafine particles (UFPs) are ubiquitous in the atmosphere and occur at high number concentrations. Despite their ability to penetrate deep into the respiratory system, their harmfulness remains insufficiently studied, primarily due to the lack of reliable standardised and harmonized long-term global exposure data. In this study, we applied an ecological approach to provide an exploratory assessment of the long-term exposure to UFPs from 2010 to 2019 in high-income countries (HICs) in relation to cardiovascular disease (CVD) risk using publicly available country-level aggregate data. To minimize social and demographic confounding factors and use reliable UFP estimation, we focus exclusively on HICs and the findings should not be generalized globally. Using a newly developed global UFP data set, we estimated population-weighted exposure (PWE) over the past decade. These estimates were combined with CVD aggregate data to identify statistically significant co-occurrences between PWE of UFPs and three health outcomes: disability-adjusted life years (DALYs), years of life lost (YLLs), and years of life lived with disability (YLDs). The findings suggest consistent patterns between long-term exposures to UFPs and CVDs. Aligning with the current literature, we suggest that further research into possible effects on CVDs due to long-term UFPs exposure is needed. Coherent with the last EU directives, our findings highlight the relevance of monitoring UFPs as a public health priority even when PM 2.5 mass-based standards are met. While our conclusions are limited to group level associations, our ecological analysis could serve as a preliminary step toward establishing consistent UFP exposure-response relationships.