Effects of traffic-related air pollution on exercise endurance, dyspnea and cardiorespiratory physiology in health and COPD - A randomized, placebo-controlled crossover trial.
BACKGROUND
Individuals with COPD have increased sensitivity to traffic-related air pollution (TRAP) such as diesel exhaust (DE), but little is known about the acute effects of TRAP on exercise responses in COPD.


RESEARCH QUESTION
Does pre-exercise exposure to TRAP (DE300, PM2.5=300 μg/m3) have greater adverse effects on exercise endurance, exertional dyspnea, and cardiorespiratory responses to exercise in participants with mild-to-moderate COPD compared to former smokers with normal spirometry and healthy controls?


STUDY DESIGN AND METHODS
In this double-blind, randomized, placebo-controlled, crossover study, 11 healthy never-smokers, 9 ex-smokers without COPD and 9 ex-smokers with COPD were separately exposed to filtered air (FA) and DE300 for 2 hours separated by a minimum of 4 weeks. Participants performed symptom limited constant load cycling tests within 2.5 hours of exposure with detailed cardiorespiratory and exertional symptom measurements.


RESULTS
There was a significant negative effect of TRAP on exercise endurance time in healthy controls (DE300 vs. FA: 10.2±8.2 vs. 12.9±9.5 min, respectively; p=0.03), but not in ex-smokers without COPD (10.1±6.9 vs. 12.2±8.0 min; respectively, p=0.57) or ex-smokers with COPD (9.8±6.4 vs. 8.4±6.6 min, respectively, p=0.31). Furthermore, significant increases in inspiratory duty cycle and absolute end-expiratory and end-inspiratory lung volumes were observed, and dyspnea ratings were elevated at select submaximal measurement times only in healthy controls. INTERPRETATION: Contrary to our hypothesis, it was the healthy controls rather than the ex-smokers with and without COPD that were negatively impacted by TRAP during exercise.
['Syed|Nafeez|N|', 'Ryu|Min Hyung|MH|', 'Dhillon|Satvir|S|', 'Schaeffer|Michele R|MR|', 'Ramsook|Andrew H|AH|', 'Leung|Janice M|JM|', 'Ryerson|Christopher J|CJ|', 'Carlsten|Christopher|C|', 'Guenette|Jordan A|JA|', '|||']
Air pollution exercise COPD diesel exhaust controlled exposure