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Member Research and Reports

Taiwan Researchers Find the Relation between Traffic-Related Air Pollution and Carotid Intima-Media Thickness

Long-term exposures to traffic-related air pollution of PM2.5abs, PM10, NO2, and NOx are positively associated with subclinical atherosclerosis in middle-aged adults, according to a study led by researchers at National Taiwan University. The study has been published in Environmental Health Perspectives in August.

The study is conducted by Dr. Ta-Chen Su, National Taiwan University Hospital, and Prof. Chang-Chuan Chan, the corresponding author from National Taiwan University.

The inhalation of particulate matter (PM) is known to accelerate or enhance the development of atherosclerosis, and triggers clinical ischemic events. Increased carotid intima-media thickness (CIMT) is an important indicator of subclinical atherosclerosis and provides a means to assess the development and progression of atherosclerotic vascular disease.

This study is aimed to evaluate the association between one-year average exposure to traffic-related air pollution and CIMT for middle-aged adults in Taipei, Taiwan. “We applied land-use regression models developed by the European Study of Cohorts for Air Pollution Effects (ESCAPE) to estimate each subject’s one-year average exposure to traffic-related air pollutants with particulate matter diameters ≤ 10 μm (PM10) and ≤ 2.5 μm (PM2.5) and the absorbance levels of PM2.5 (PM2.5abs), nitrogen dioxide (NO2), and nitrogen oxides (NOx) between 2009 and 2011 in Taipei,” said Dr. Ta-Chen Su. One-year average air pollution exposures are 44.21 ± 4.19 μg/m3 for PM10, 27.34 ± 5.12 μg/m3 for PM2.5, and (1.97 ± 0.36) × 10–5/m for PM2.5abs.

Multivariate regression analyses shows average percentage increases in maximum left CIMT of 4.23 percent (95 percent CI: 0.32, 8.13) per 1.0 × 10–5/m increase in PM2.5abs; 3.72 percent (95 percent CI: 0.32, 7.11) per 10-μg/m3 increase in PM10; 2.81 percent (95 percent CI: 0.32, 5.31) per 20-μg/m3 increase in NO2; and 0.74 percent (95 percent CI: 0.08, 1.41) per 10-μg/m3 increase in NOx. “We conclude that long-term exposures to traffic-related air pollution of PM2.5abs, PM10, NO2, and NOx are positively associated with subclinical atherosclerosis in middle-aged adults,” said Prof. Chang-Chuan Chan. The study supports the potential importance of composition or components of PM2.5 in cardiovascular health and the establishment of regulations for PM2.5abs. Because the urban areas that suffer most from air pollution in the world are located in Asian countries such as China and India, the emerging data regarding adverse cardio vascular effects in Taiwan should be urgently considered by Asian countries.