###### Abstract
Likewise, PM\({}_{2.5}\) (<2.5 microns) has been related to a drop in FEV\({}_{1}\) and FVC in subjects who lived in the vicinity of a highway [22]. Physical exercise increases these effects as their intensity and duration increase as a consequence of the increased work of breathing. Minute ventilation, together with greater exposure to the pollutant, will determine their inhaled load in the airways [16; 23; 24]. Several authors have observed that, during moderate and maximum exercise in an environment contaminated with O\({}_{3}\), there are more symptoms, such as dyspnea, respiratory distress, and a feeling of tightness in the chest, which quickly lead to the cessation of exercise [25; 26; 27; 28]. Several authors have shown an alteration in lung function parameters (FEV\({}_{1}\), FVC, and FEF\({}_{25-75}\)) in both healthy trained and untrained subjects exposed to high concentrations of O\({}_{3}\) while performing physical exercise [15], with some of them even experiencing the effects a few hours after exercising [29]. Abnormal respiratory symptoms have also been observed after one hour of exercise and one hour of rest in an environment contaminated with PM\({}_{10}\) and PM\({}_{2.5}\), however, no spirometric changes were found [21]. In another study, [PERSON] et al. [30] observed decreased mucociliary clearance, decreased pH in the expired air, and increased symptoms of respiratory distress in motorcyclists who were chronically exposed to NO\({}_{2}\) during heavy traffic for 5-8 h a day, five days a week. Likewise, the practice of aerobic exercise in the open air at an average PM\({}_{2.5}\) concentration of 65.1 ug/m\({}^{3}\) over a period of five days also altered mucociliary clearance [31]. Yet, the study conducted by [PERSON] et al. (2015) demonstrated improvements in lung function with physical exercise in a highly polluted environment; however, an acute pulmonary inflammatory effect was also observed [32]. Other studies on healthy subjects who performed strenuous long-duration exercise (between \(\sim\)2-5 h) in a polluted environment (PM\({}_{2.5}\) and O\({}_{3}\)) did not show deleterious effects on lung function parameters [33; 34]. This should be interpreted with caution, since the systematization of this behavior, which constantly promotes an oxidative/inflammatory lung environment, could mean permanent lung damage in the future. Children are especially sensitive to contact with atmospheric pollutants, which leads to a higher rate of school absenteeism and an increase in high and low airway infections [35], and alters lung function, thereby increasing the probability of death [36]. Infant lungs show an incomplete respiratory tree where the pulmonary epithelium is being formed, which has been associated with greater permeability of this structure. Similarly, some studies have suggested that long-term exposure to air pollutants could potentially affect children's lung development [37; 38; 39]. Modification of lung function in children who are active in polluted air has been associated with high concentrations of O\({}_{3}\)[40], MP\({}_{10}\), NO\({}_{x}\), and CO [41]. [PERSON] et al. [42] demonstrated that there was an association between the prevalence of asthma in children and prolonged and intense exercise done outdoors with high levels of O\({}_{3}\). In the case of adults, moderate exercise increases the amount of particulate material entering the lungs by 4.5 times versus resting [12], where similar results are expected for the other environmental pollutants. One group of subjects who can be particularly affected by polluted air is the group of amateur long-distance athletes (e.g., marathons, cross-country cycling). Thus, a group of cyclists exercised in open-top field chambers for dispensing O\({}_{3}\), showing a decrease in FEV\({}_{1}\) after moderate exercise for sixty minutes [24]. Furthermore, a group of cyclists in competition (75 min) increased their respiratory symptoms (wheezing, dyspnea) after inhaling a mixture of pollutants.