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Health Effects
Published in Wayne T. Davis, Joshua S. Fu, Thad Godish, Air Quality, 2021
Wayne T. Davis, Joshua S. Fu, Thad Godish
When the primary air quality standard for SO2 (0.03 ppmv [80 μg/m3] annual mean, 0.14 ppmv [365 μg/m3] maximum 24-h concentration) was promulgated in 1971, no health effects had been reported for short-term exposures (<1 h) at levels observed in the ambient environment (≤1 ppmv, 2.67 mg/m3). In 2010, the U.S. Environmental Protection Agency (U.S. EPA) revised the primary SO2 standard by establishing a new 1-h standard at a level of 75 ppb. Since 1980, numerous challenge studies conducted on asthmatic individuals have shown that when asthmatics and others with hyperactive airways are briefly exposed to SO2 at concentrations of 0.25 to 0.50 ppmv (0.66–1.3 mg/m3), they exhibit acute responses characterized by bronchoconstriction (airway narrowing) with increased airway resistance and decreased forced expiratory flow rate, and clinical symptoms of shortness of breath and wheezing. Bronchoconstriction occurs within 5–10 min of exposure and is brief in duration, with lung function returning to normal for most subjects within an hour of exposure. Such responses occur even at lower SO2 levels during moderate exercise. This results from increases in breathing rate and oral breathing and thus exposure. Oral breathing increases SO2 penetration to the lower respiratory tract and results in airway drying.
Physiology of the Airways
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Anthony J. Hickey, David C. Thompson
Smooth muscle is separated from the epithelium by the lamina propria, a region of connective tissue containing nerves and blood vessels. In the trachea, the smooth muscle connects the open ends of the incomplete cartilage rings and, therefore, constitutes only a fraction of the circumference of this component of the airways. Further down the pulmonary tree, through the bronchi and bronchioles, the contribution of the smooth muscle to the airway wall increases to the point of completely encircling the airway. Contraction or relaxation of the smooth muscle has a direct influence on airway caliber and, thereby, affects airflow in the airways. Bronchoconstriction is the result of smooth muscle contraction and is the principal cause of airway obstruction in reversible obstructive airway diseases, such as asthma. The tone or state of contraction of airway smooth muscle is subject to control by neurotransmitters released from innervating nerves, hormones, or mediators released from activated inflammatory cells.
Placebo and somatization
Published in Herman Staudenmayer, Environmental Illness, 2018
This point was clearly demonstrated by Luparello and colleagues in a series of double-blind, placebo-controlled studies on the effects of suggestion on airway resistance in asthmatics (Luparello et al., 1968; McFadden et al., 1969). Bronchoconstriction in response to saline occurred in about 50% of subjects who were told they were inhaling the nebulized allergen to which they attributed their asthma attacks. Bronchoconstriction was measured with changes in airway resistance, a measure obtained in a whole-body Plethysmograph. Airway resistance is less effort dependent and therefore less likely to be affected by the subject than some other pulmonary function measures. These investigators also identified a mechanism — activation of efferent cholinergic pathways — through which the phenomenon was mediated by demonstrating that they could prevent the bronchoconstriction response to suggestion by intravenous atropine sulfate.
Differences in lung function, bronchial hyperresponsiveness and respiratory health between elite athletes competing in different sports
Published in European Journal of Sport Science, 2023
Guro P. Bernhardsen, Julie Stang, Thomas Halvorsen, Trine Stensrud
Even though studies indicate high lung volumes and high peak ventilatory capacity in elite athletes, several studies also suggest a high prevalence of exercise-induced respiratory symptoms, exercise-induced bronchoconstriction (EIB) and bronchial hyperresponsiveness (BHR) (Bougault et al., 2010; Fitch, 2012; Stang et al., 2016). Bronchial hyperresponsiveness (BHR) has particularly been observed in endurance athletes practicing winter- and water sports (Atchley & Smith, 2020; Mäki-Heikkilä et al., 2020; Stang et al., 2016), possibly linked to heavy exposures to cold dry winter-air or to the chemical disinfectants used in swimming pools (Atchley & Smith, 2020; Couto et al., 2018). Couto et al. (2015) have therefore suggested two phenotypes of asthma among elite athletes; a “sports asthma” defined by the presence of exercise-induced respiratory symptoms and BHR, and a more regular “atopic asthma” characterised by allergy, eosinophilic inflammation and increased expired nitric oxide (FENO). The etiology of these two phenotypes probably differs, and to provide optimal treatment it is recommended that athletes’ respiratory health and atopy are systematically tested (Couto et al., 2015, 2018).
The difference in risk of chronic pulmonary disease morbidity and mortality between former elite athletes and ordinary men in Finland
Published in European Journal of Sport Science, 2020
Titta K. Kontro, Seppo Sarna, Jaakko Kaprio, Urho M. Kujala
Asthma, airway hyperresponsiveness (AHR), and exercise-induced bronchoconstriction (EIB) appear to be more common in elite athletes than less-trained controls (Helenius, Lumme, & Haahtela, 2005; Turcotte, Langdeau, Thibault, & Boulet, 2003). Correspondingly, epidemiologic studies suggest that self-reported and physician-diagnosed asthma are twice as common in Finnish athletes (Alaranta et al., 2004) and elite Norwegian athletes (Nystad, Harris, & Borgen, 2000) than in randomly selected age-matched and sex-matched control populations. The higher prevalence of asthma reported in athletes may be a result of overdiagnosis, particularly because a diagnosis of asthma is often made on the basis of the history alone (Parsons, O’Brien, Lucarelli, & Mastronarde, 2006) and athletes often experience the symptoms during intensive exercise only.
Effect of asthma and six-months high-intensity interval training on heart rate variability during exercise in adolescents
Published in Journal of Sports Sciences, 2019
M. A. McNarry, M. J. Lewis, N. Wade, G. A. Davies, Con Winn, W. T. B. Eddolls, G. S. Stratton, K. A. Mackintosh
A commonly cited barrier for those with asthma is a fear of exercise-induced bronchoconstriction (Carson et al., 2013), which is more likely to occur during continuous aerobic exercise (Sidiropoulou, Fotiadou, Tsimaras, Zakas, & Angelopoulou, 2007). In contrast, intermittent exercise places a lower burden on the respiratory system (Beauchamp et al., 2010), suggesting that high-intensity interval training (HIIT) has potential as an exercise modality to help manage asthma. Indeed, in adults, HIIT has been more effective than aerobic endurance training at eliciting improvements in HRV (Heydari, Boutcher, & Boutcher, 2013; Kiviniemi et al., 2014) although similar studies have produced no effects in children, despite significant increases in aerobic fitness (Mandigout et al. (2002) and Gamelin et al. (2009)) . The reasons for these discrepancies are unclear and further research is required to elucidate whether they reflect physiological or methodological differences.