3.3 Non-allergic and mixed rhinitis
Non-allergic rhinitis (NAR) is defined as a chronic rhinitis in the absence of infection or systemic allergen-specific IgE and comprises a very heterogenous patient group 37. In everyday life, an overlap between AR and NAR is very frequently seen and addressed as mixed rhinitis. So far, reliable data on the occurrence of NAR in the athlete population is scarce but studies reporting on mixed rhinitis show a prevalence as high as 74 % in athletes 31.
Within all sports disciplines NAR is again most frequently reported in aquatic athletes, possibly due to exposures to pool chlorination products. Several studies showed a significantly higher prevalence of NAR in swimmers compared to non-swimming athletes and controls3. Gelardi and colleagues showed that within a population of swimmers with rhinitis, 76 % had NAR of whom 35% presented with a neutrophilic nasal inflammation 38. Another study confirmed this neutrophilic nasal influx in swimmers, in combination with an increased MCT compared to controls38, 39. A recent study showed an increase of neuropeptides and epithelial injury markers in nasal secretions of swimmers after training, suggesting a direct irritant effect on the airway mucosa of the chlorination products, which has also been shown in a mouse model of chlorine-induced airway hyperreactivity34. Also air pollution might induce non-allergic dysfunction: the nasal mucociliary clearance time (MCT) was prolonged in runners who ran in polluted streets when compared to running in the woods 40, although the inflammatory response to exposure to pollutants seems more mitigated in athletes compared to sedentary controls 41.