Aerobic exercise in polluted urban environments: effects on airway defense mechanisms in young healthy amateur runners

Abstract

In this study, the effects of aerobic exercise on the upper airways and their defense mechanisms were investigated in athletes. The athletes ran in two different environments: the downtown streets of the city of São Paulo (Street), more polluted, and an urban forest (Forest), less polluted. Thirty-eight young healthy athletes ran for 45 min d randomly during five consecutive days, with an interval of 48 h before changing environment. Clinical parameters and respiratory tract defense markers were evaluated before and after the first run on Mondays (1 d) and on Fridays (5 d). Street presented higher mean PM concentrations (65.1 ± 39.1 µg m, p < 0.001) and lower temperature (22.0 °C, p = 0.010) than Forest (22.6 ± 15.3 µg m and 22.8 °C). After 1 d Street running, subjects showed an increment in heart rate (p < 0.001). At day 5, there was twice the number of athletes with impaired nasal mucociliary clearance (MCC) in the Street runners group when compared to the Forest runners group. Exhaled breath condensate pH values increased in the Forest group, with significant differences between groups in day 1 (p = 0.006) and day 5 (p < 0.001), despite the fact that both groups showed values within the normal range. After exposure to both environments, the number of cells in the nasal lavage fluid was reduced after exercise (p = 0.014), without alterations in cell type and IL-8 and IL-10 concentrations. Aerobic exercise can either maintain or acutely enhance MCC and it may help to regulate inflammatory responses in the airways. Here we show that exercise practice in polluted outdoor environment, over a 5 d period, impairs MCC. In contrast, athletes running in the less polluted environment (Forest) show higher exhaled breath condensate pH values when compared to those who exercised in a more polluted environment (Street).

Respiratory Effects of Exposure to Traffic-Related Air Pollutants During Exercise

“…Other studies assessed exhaled breath condensate (EBC) biomarkers. Two studies in runners reported unchanged EBC pH after exercise in clean or polluted air (47,53). In runners, concentration of interleukin (IL)-1β, IL-6, or IL-2 in EBC was unchanged relative to exposure to air pollutants (46), while another study reported decreased nitrate and increased malondialdehyde (MDA) concentrations, suggesting increased oxidative stress in the airways during exercise in highly polluted areas (29).…”

Regular running in an air-polluted environment: physiological and anthropometric protocol for a prospective cohort study (Healthy Aging in Industrial Environment Study – Program 4)

“…17 Furthermore, 5 days of aerobic outdoor exercise significantly impaired nasal mucociliary clearance in the street runners group when compared with the forest runners group. 18 This suggests that regular outdoor exercise in AP can be potentially harmful to cardiorespiratory health.…”

A Review of the Usefulness of Non-invasive Exhaled Breath Condensate pH Analysis for Diseases Diagnosis with Elements of Meta-analysis: An Update from 2012

“…Mean results higher than Air pollution and exposure to certain substances are important factors that can influence airway acidity, and it is important to keep this in mind when analyzing EBC pH as a biomarker for various clinical conditions. Substances that have been proven to increase the level of hydrogen ions in exhaled breath-thus, lowering the pH value-include: O3 [73,74], SPM (suspended particulate matter) [73,75,76], black carbon [77], NO2 [76], benzene [76], ethylbenzene [76], TiO2 [78], PAH (polycyclic aromatic hydrocarbons) [79], wood dust [80], wood smoke [81], and cigarette smoke [82,83].…”