Air pollution, exercise, and heat stress

Exercising in the urban center: Inflammatory and cardiovascular effects of prolonged exercise under air pollution

The aim of this study was to investigate, in a well-controlled experimental environment, whether air pollution from an urban center would affect inflammatory and cardiorespiratory responses during prolonged moderate exercise (i.e., 90 min). Ten healthy men performed two experimental trials under filtered and polluted air, inside an environmental chamber located in Sao Paulo downtown, Brazil. Blood samples were obtained at rest, 30, 60, and 90 min of the exercise to determine the serum cytokines concentration, while arterial pressure was recorded immediately after the exercise. The serum cytokines were not altered until 60 min of exercise for both conditions (P > 0.05). Otherwise, at 90 min of exercise, the IL-6 (P = 0.047) and vascular endothelial growth factor (VEGF) (P = 0.026) were significantly higher and IL-10 tended to decrease (P = 0.061) in polluted air condition compared to filtered air condition. In addition, both systolic (P = 0.031) and diastolic (P = 0.009) arterial pressure were higher in polluted air condition than filtered air condition. These findings demonstrate that the exercise of longer duration (i.e., 90 min), but not of shorter duration (i.e., <60 min), performed in vehicular air pollution condition results in pronounced pro-inflammatory and increased arterial pressure responses.

The health effects of exercising in air pollution

The health benefits of exercise are well known. Many of the most accessible forms of exercise, such as walking, cycling, and running often occur outdoors. This means that exercising outdoors may increase exposure to urban air pollution. Regular exercise plays a key role in improving some of the physiologic mechanisms and health outcomes that air pollution exposure may exacerbate. This problem presents an interesting challenge of balancing the beneficial effects of exercise along with the detrimental effects of air pollution upon health. This article summarizes the pulmonary, cardiovascular, cognitive, and systemic health effects of exposure to particulate matter, ozone, and carbon monoxide during exercise. It also summarizes how air pollution exposure affects maximal oxygen consumption and exercise performance. This article highlights ways in which exercisers could mitigate the adverse health effects of air pollution exposure during exercise and draws attention to the potential importance of land use planning in selecting exercise facilities.

Effets du tabagisme et du niveau de dépendance nicotinique sur la capacité aérobie chez le sportif

AIM

To assess the effects of smoking and the degree of nicotine dependence on aerobic capacity in smokers undergoing endurance training.

METHODS

126 smokers aged between 18 and 31 years playing in the football teams of the Congolese first (n = 64) and second divisions (n = 64) co-operated voluntarily in the study. Aerobic capacity was determined by Cooper's running test. Absolute VO2max and that related to body weight were subsequently calculated. The degree of nicotine dependence of each subject was assessed by the Fagerstrom questionnaire. A control group consisted of 125 non-smokers playing at the same level.

RESULTS

The values of VO2max achieved by the smokers were significantly less (p < 0.05) than those achieved by the non-smokers. The first division players had a higher aerobic capacity than the second division players. Moreover the analysis of variance showed an influence of nicotine dependence on aerobic capacity. The subjects who were heavily dependent on nicotine had lower VO2max values than those less dependent. Moreover for the same level of dependence there were differences between the first and second division players.

CONCLUSION

The inhalation of tobacco smoke leads to an alteration in aerobic capacity. This is directly influenced bythe degree of nicotine dependence whatever the level of training of the subject.

Effects of smog on absenteeism in forestry workers

Absenteeism among 161 Dutch forestry workers was investigated in a cohort study. The rate of taking sick leave was related to the concentrations of sulfate and ozone in ambient air, the air temperature, and the relative humidity. The incidence of absenteeism was treated as a Poisson process, with the size of population at risk as the offset factor and with the environmental monitoring data as hazard factors. There appeared to be some overdispersion; therefore, in a second analysis the incidence of absenteeism was also treated as a negative binomial outcome. With the exception of a separate overdispersion parameter in the negative binomial approach, both methods yielded approximately the same results. Although no significant association was found between absence rate and the measured ambient-air-quality data, there appeared to be a time lag of 3 d between a peak in temperature and 1 d in absenteeism.

The effects of cigarette smoking on maximal oxygen consumption and selected physiological responses of elite team sportsmen

The acute and chronic effects of cigarette smoking on selected physiological responses were determined in seven well-trained non-smokers and seven well-trained habitual smokers. Non-smokers and smokers did not differ significantly with respect to maximal oxygen consumption (VO2max). The acute effect of smoking two cigarettes immediately prior to a graded exercise stress test on a treadmill ergometer did not significantly alter the VO2max of either group. However, the time taken for non-smokers to reach exhaustion decreased significantly (F = 5.381, P less than 0.05) by a mean of 0.64 min. Smokers recorded lower scores for forced vital capacity (FVC) and forced expiratory volume in the 1st s exhalation (FEV1) than non-smokers. Only the mean FVC of smokers recorded 5 min post-exercise was significantly altered by pre-exercise smoking. No differences were found between the resting heart rates (HR) of non-smokers and smokers. Smoking two cigarettes significantly (F = 44.720, P less than 0.01) increased the mean resting HR of smokers and non-smokers by 15.8 beats X min-1 and 15.6 beats X min-1 respectively. No alteration to the exercise HR of either group was found under smoking conditions of the VO2max tests.

Aggravation of exercise performance in patients with anemia by 3% carboxyhemoglobin

To evaluate the effect of breathing 50 ppm carbon monoxide (CO) on exercise capacity in persons with anemia, 10 nonsmoking subjects with chronic anemia (mean hemoglobin 8.9 g%) were studied. No subject had heart or lung disease. By double-blind, randomized, crossover design, duration of fatigue-limited exercise after breathing CO and purified air for 1 hr was compared. Mean carboxyhemoglobin levels increased from 2.14 to 3.38% after breathing CO and decreased from 2.15 to 1.86% after breathing purified air, P less than 0.004. Mean exercise duration decreased from 270.8 to 221.0 sec after breathing CO in contrast to an increase from 267.9 to 271.6 sec after breathing purified air, P less than 0.0001. Hence, in the absence of clinical heart or lung disease, increasing carboxyhemoglobin concentrations aggravate exercise performance in nonsmokers with chronic anemia.

Air Pollution: Adverse Effects on Athletic Performance

Airborne pollutants can have significant objective and subjective effects on athletes and can cause substantial decrements in their performance.

Aggravation of angina pectoris by two percent carboxyhemoglobin

A double-blind, randomized, crossover study was performed in 15 patients with stable angina to evaluate the effect of breathing carbon monoxide (CO), which raised the carboxyhemoglobin (COHb) from 1.09% to 2.02%, versus breathing compressed, purified air, which lowered the COHb from 1.07% to 1.00% on exercise duration until angina. The exercise duration until angina was 324.5 seconds in the air control period and 330.3 seconds after purified air compared to 321.7 seconds in the CO air control period and 289.7 seconds after CO. Breathing CO to raise the COHb from 1.09% to 2.02% caused a decrease in exercise duration until angina pectoris (p less than 0.001) and a reduction in product of systolic blood pressure times heart rate at the onset of angina (p less than 0.001). These data indicate that a 2% COHb level aggravates angina pectoris due to coronary artery disease.

Carbon monoxide and ventricular fibrillation threshold in normal dogs

In a blind, randomized study, the effect of breathing 100 ppm of carbon monoxide versus compressed, purified air for 2 hr on ventricular fibrillation threshold was investigated in twenty anesthetized normal open-chested dogs. The mean arterial carboxyhemoglobin level was 1.12% in the air control period, 0.99% after air, 1.10% in the carbon monoxide control period, and 6.48% after carbon monoxide. Carbon monoxide increased the mean arterial carboxyhemoglobin (P less than .001). Mean ventricular fibrillation thresholds were 19.9 +/- 6.5 mA in the carbon monoxide control period, 15.7 +/- 5.6 mA after carbon monoxide 20.8 +/- 6.3 mA in the air control period, and 24.5 +/- 9.5 mA after air. Carbon monoxide decreased the ventricular fibrillation threshold (P less than .005). These data show that breathing 100 ppm of carbon monoxide for 2 hr reduces the ventricular fibrillation threshold in anesthetized normal open-chested dogs.

Carbon monoxide and ventricular fibrillation threshold in dogs with acute myocardial injury

In a blind, randomized study, the effect of breathing 100 p.p.m. of CO versus compressed, purified air for 2 hours on ventricular fibrillation threshold (VFT) was investigated in 21 dogs with acute myocardial injury. The mean arterial carboxyhemoglobin was 1.16 per cent in the air control period, 1.07 per cent after air, 1.08 per cent in the CO control period, and 6.34 per cent after CO. In comparison to air, CO increased the mean arterial carboxyhemoglobin (P less than 0.001). One dog developed spontaneous ventricular fibrillation 100 minutes after CO. Mean VFTs in the other 20 dogs were 12.8 +/- 6.8 milliamperes after CO, 11.2 +/- 6.0 milliamperes in the air control period, and 15.0 +/- 5.1 milliamperes after air. In comparison to air, CO decreased the VFT (P less than 0.001). These data show that breathing 100 p.p.m. of CO for 2 hours reduces the VFT in dogs with acute myocardial injury.

Effect of carbon monoxide on exercise performance in chronic obstructive pulmonary disease

We evaluated the effect of breathing 100 ppm of carbon monoxide versus compressed, purified air for 1 hour on exercise performance in 10 patients with chronic obstructive pulmonary disease in a double-blind, randomized, crossover study. The mean arterial carboxyhemoglobin was 1.48 per cent in the carbon monoxide control period and increased from 1.43 to 4.08 per cent after breathing carbon monoxide (P less than 0.001). The mean arterial carboxyhemoglobin level was 1.52 percent in the air control period and decreased from 1.47 to 1.34 per cent after purified air (P less than 0.001). The mean exercise time until marked dyspnea decreased from 218.5 seconds in the carbon monoxide control period to 146.6 seconds after breathing carbon monoxide (P less than 0.001). The mean exercise time was 219.9 seconds in the air control period and 221.3 seconds after purified air (P not significant). Breathing 100 ppm of carbon monoxide for 1 hour caused a significant reduction in exercise performance in patients with chronic obstructive pulmonary disease.

Comparative study of cardiovascular function and ventricular premature complexes in smokers and nonsmokers during maximal treadmill exercise

Maximal treadmill exercise tests were performed by 586 male members of the Indiana State Polic Force who were free of clinical evidence of cardiovascular disease. The study population was categorized into groups according to cigarette smoking experience and subgroups according to age and number of pack-years of exposure. There were 176 nonsmokers (30 percent), 268 current smokers (46 percent) and 142 former smokers who had abstained for at least 1 year (24 percent). No statistically significant differences were found in the prevalence of exercise-induced ventricular premature complexes when current smokers were compared with nonsmokers or former smokers either as a group or as subgroups classified by age. The duration of maximal exercise and the peak heart rate and systolic blood pressure during maximal exercise were compared for each group. The duration of maximal exercise was significantly shorter in smokers (P less than 0.001) and former smokers (P less than 0.005) than in nonsmokers. Maximal systolic blood pressure during exercise was greater in smokers than in nonsmokers (P less than 0.01) but did not differ significantly between nonsmokers and former smokers. Maximal heart rate during exercise was significantly lower in smokers (P less than 0.01) and former smokers (P less than 0.01) than in nonsmokers. In conclusion, there was a statistically significant difference in the duration of exercise and the maximal heart rate and systolic blood pressure attained during exercise between men who smoked and nonsmokers, but the prevalence of the exercise-induced ventricular premature complexes did not appear to be influenced by smoking habits.