Impact of Cold exposure on individuals with clinical disease. Respiratory response to Cold exposure.

Cold dry air can have several effects on the respiratory system, especially in individuals with chronic lung diseases. Asthma is a chronic inflammatory airway disease characterized by repeated episodes of wheezing, coughing and breathlessness, and the global prevalence of doctor-diagnosed asthma in adults has been reported to be 4.3%, with wide differences between countries. Exercise-induced asthma (EIA) is present in up to 90% of all individuals with asthma, and the cold, dry air during the winter months is particularly conducive to the development of EIA in susceptible individuals. Asthma rates vary widely among sports, and both the type of exercise and the environment influence the severity of EIA in the individual asthmatic athlete. The main determinants of the bronchoconstrictor response to exercise are intensity (minute ventilation), the temperature and humidity of the inspired air, and baseline airway reactivity. Invasive studies have found pathological changes in airway mucosa that suggest airway remodelling, indicating that hyperventilation of cold, dry air represents a significant stress to the airways that could lead to asthma. Occupational studies indicate that prolonged exposure to cold air may induce a chronic asthma-like condition, even in healthy subjects. EIA should be treated in athletes according to the same principles as in ordinary asthma patients. Competitive athletes must also consider doping control issues, since not all antiasthmatic medications are approved by the World Anti-doping Agency. The severity of EIA can also be reduced by raising the temperature and humidity of the inspired air, and heat-exchanging masks and devices have been developed for this purpose.