Effect of daily pollution exposure in the autonomic system in traffic workers of Sao Paulo

Background: Heart rate variability is used to quantify autonomic response and to detect cardiovascular diseases. Chronic pollution exposure is known to increase arterial pressure and the incidence of cardiac ischemia leading to cardiovascular diseases and death; however the effect of variation of daily pollution in chronically exposed subjects remains poorly known. Objective: To study the effect of acute pollution exposition in the autonomic system at rest and exercise in traffic workers. Methods: Twenty-one male subjects were studied in 4 randomized working days (once a week) with distinct pollution exposure. The amount of pollution (ozone (O3) and nitrogen dioxide (NO2)) was measured 24 hours before the day test by a pollution analyzer. Activity of autonomic system response was measured during 5 minutes either at rest or during treadmill exercise (moderate intensity). Results: The levels of exposure pollution were considered intermediate and ranged from 133.9 μg/m3 to 317.2μg/m3 and 0.1μg/m3 and 26.3 μg/m3 (respectively, of NO2 and O3). In the days with higher levels of pollution, it was observed a reduction in the activity parasympathetic system (RMSSD) at rest (p<0.05). In addition, it was observed a linear correlation between the levels of pollution and a reduction in the RMSSD measure at rest (r=0.52; p=0.01). Interesting, during exercise, the parasympathetic response was increased in the most polluted days (p<0.05). Conclusion: Our results suggest that even low changes in daily pollution exposure selectively modify the autonomic system to either rest of exercise. Supported by CNPq.