Exposure to air pollution near a steel plant and effects on cardiovascular physiology: A randomized crossover study.

Abstract: Background: Iron and steel industry is an important source of air pollution emissions. Few studies have investigated cardiovascular effects of air pollutants emitted from steel plants. Objective: We examined the influence of outdoor air pollution in the vicinity of a steel plant on cardiovascular physiology in Sault Ste. Marie, Canada. Methods: Sixty-one healthy, non-smoking subjects (females/males=33/28, median age 22 years) spent 5 consecutive 8-hour days outdoors in a residential area neighbouring a steel plant, or on a college campus approximately 5 kilometres away from the plant, and then crossed over to the other site with a 9-day washout. Mid day, subjects underwent daily 30-minute moderate intensity exercise. Blood pressure (BP) and pulse rate were determined daily and post exercise at both sites. Flow-mediated vasodilation (FMD) was determined at the site near the plant. Air pollution was monitored at both sites. Mixed-effects regressions were run for statistical associations, adjusting for weather variables. Results: Concentrations of ultrafine particles, sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) were 50–100% higher at the site near the plant than at the college site, with minor differences in temperature, humidity, and concentrations of particulate matter ≤2.5μm in size (PM2.5) and ozone (O3). Resting pulse rate [mean (95% confidence interval)] was moderately higher near the steel plant [+1.53bpm (0.31, 2.78)] than at the college site, male subjects having the highest pulse rate elevation [+2.77bpm (0.78, 4.76)]. Resting systolic and diastolic BP and pulse pressure, and post-exercise BP and pulse rate were not significantly different between two sites. Interquartile range concentrations of SO2 (2.9ppb), NO2 (5.0ppb) and CO (0.2ppm) were associated with increased pulse rate [0.19bpm (−0.00, 0.38), 0.86bpm (0.03, 1.68), and 0.11bpm (0.00, 0.22), respectively], ultrafine particles (10,256count/cm3) associated with increased pulse pressure [0.85mmHg (0.23, 1.48)], and NO2 and CO inversely associated with FMD [−0.14% (−0.31, 0.02), −0.02% (−0.03, −0.00), respectively]. SO2 during exercise was associated with increased pulse rate [0.26bpm (0.01, 0.51)]. Conclusion: Air quality in residential areas near steel plants may influence cardiovascular physiology. [Copyright &y& Elsevier]