Emulating Near-Roadway Exposure to Traffic-Related Air Pollution via Real-Time Emissions from a Major Freeway Tunnel System

Epidemiological and toxicological studies continue to demonstratecorrelative and causal relationships between exposure to traffic-related air pollutionand various metrics of adverse pulmonary, cardiovascular, and neurological healtheffects. The key challenge for in vivo studies is replicating real-world, near-roadwayexposure dynamics in laboratory animal models that mimic true human exposures.The advantage of animal models is the accelerated time scales to show statisticallysignificant physiological and/or behavioral response. This work describes a novelexposure facility adjacent to a major freeway tunnel system that provides a platformfor real-time chronic exposure studies. The primary conclusion is that particulatematter (PM) concentrations at this facility are routinely well below the NationalAmbient Air Quality Standards (NAAQS), but studies completed to date stilldemonstrate significant neurological and cardiovascular effects. Internal combustionengines produce large numbers of ultrafine particles that contribute negligible mass tothe atmosphere relative to NAAQS regulated PM2.5but have high surface area and mobility in the body. It is posited here thatcurrent federal and state air quality standards are thus insufficient to fully protect human health, most notably the developing andaging brain, due to regulatory gaps for ultrafine particles.

Automated summary

Epidemiological and toxicological studies have consistently shown the adverse effects of traffic-related air pollution on pulmonary, cardiovascular, and neurological health. Replicating real-world exposures in laboratory animals is a challenge, but animal models offer a faster way to observe physiological and behavioral responses. A new exposure facility has been developed to study chronic exposure in real time, revealing that current air quality standards do not adequately protect against ultrafine particles.