Toxicity of airborne particles—established evidence, knowledge gaps and emerging areas of importance

Abstract

Epidemiological research has taught us a great deal about the health effects of airborne particulate matter (PM), particularly cardiorespiratory effects of combustion-related particles. This has been matched by toxicological research to define underlying mechanistic pathways. To keep abreast of the substantial challenges that air pollution continues to throw at us requires yet more strides to be achieved. For example, being aware of the most toxic components/sources and having a definitive idea of the range of associated disease outcomes. This review discusses approaches designed to close some of these knowledge gaps. These include a focus on particles arising from non-exhaust PM at the roadside and microplastics—both of which are becoming more relevant in the light of a shift in PM composition in response to global pressure to reduce combustion emissions. The application of hypothesis-free approaches in both mechanistic studies and epidemiology in unveiling unexpected relationships and generating novel insights is also discussed. Previous work, strengthening the evidence for both the adverse effects and benefits of intervention tell us that the sooner we act to close knowledge gaps, increase awareness and develop creative solutions, the sooner we can reduce the public health burden attributable to these complex and insidious environmental pollutants. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Long-Term Exposure to Fine Particle Elemental Components and Natural and Cause-Specific Mortality—a Pooled Analysis of Eight European Cohorts within the ELAPSE Project

“…The observed associations of Ni and V with mortality could be due to the components per se or to other components in emissions from oil combustion. Studies have suggested V in can induce oxidative stress, which is considered central to producing many of the negative health effects attributed to PM ( Kelly and Fussell 2020 ; Zhang et al. 2009 ).…”

“…The observed associations of Ni and V with mortality could be due to the components per se or to other components in emissions from oil combustion. Studies have suggested V in PM 2:5 can induce oxidative stress, which is considered central to producing many of the negative health effects attributed to PM (Kelly and Fussell 2020;Zhang et al 2009). However, there is no stronger support from experimental studies for effects of V than for Ni, Fe and Cu, for which oxidative stress is also a major pathway.…”

Microplastics and human health

“…he ubiquity of microplastics (plastic particles <5 mm, including nanosized plastics <1 mm) in the global biosphere raises increasing concerns about their implications for human health (1)(2)(3). Recent evidence indicates that humans constantly inhale and ingest microplastics; however, whether these contaminants pose a substantial risk to human health is far from understood.…”

“…Microplastics may enter the human body through both inhalation and ingestion, potentially causing health effects (see the figure). A parallel can be drawn with particulate air pollution: Small particles (<2.5 mm), such as those from diesel exhaust, are capable of crossing cell membranes and triggering oxidative stress and inflammation, and have been linked with increased risk of death from cardiovascular and respiratory diseases or lung cancer (3). This parallel provides ample incentive to gather more information on the potential risk of microplastic particles.…”

Global Air Quality, past present and future: an introduction

“…The most important impacts of PM are currently the effects on human health and these remain the main driver of policy developments. Two contrasting approaches to study the effects of air pollutants on human health are epidemiology and toxicology, summarized by Gowers et al [8] and by Kelly et al [9], respectively. While PM is a focus for research, monitoring and policy development to reduce the effects on human health, there remains the problem that the relative contributions of PM components to human health effects remain unknown.…”