The study, slated for publication in the journal Environment International, looked at “ultrafine” pollutants from car exhaust rather than the larger pollutants that are traditionally the focus of air quality research. Researchers found that high concentrations of ultrafine particles — 500 times smaller in diameter than the width of a human hair — are just as toxic as larger particles. While larger particles settle in the lungs, these particles penetrate into the bloodstream, causing inflammation and elevated cholesterol levels. Chronic exposure can cause dangerous plaque buildup in the arteries and eventually lead to heart attack or stroke.
— source thinkprogress.org | 2016