Asthma is one of the most widespread diseases in the world, even if its prevalence and severity differ widely among countries and individuals. At altitude, the main problems which emerge are hypoxia and environmental and trigger factors such as exercise, hyperventilation in dry and cold air (the severity of bronchospasm induced by exercise is enhanced by hyperventilation in cold and dry air [5,22], while there is a reduction in aeroallergens and atmospheric pollution.
TABLE 1. Effect of different climatic conditions at high altitude
0 Density of the air Flows T Airway resistence 0
0 Temperature 0 Humidity T Wind
Hyperventilation Asthma attack of dry and cold air
0 Inhaled allergens Positive for "respiratory" patients 0 Pollution
At 1500-2000m hypoxia is not severe, and the main environmental feature is the reduction in, or absence of, pollen, house dust mite and environmental pollution , which can play a key role in reducing the bronchial inflammation underlying airways hyper-responsiveness . Avoidance of allergen exposure (especially to mite allergens) is often recommended in asthma management and a considerable reduction in exposure to allergens exists in mountain environments, a fact which reduces the bronchial inflammation and results in a dramatic clinical improvement. All the data published on this topic confirm that exposure to moderate altitude is beneficial for asthmatics.
At higher altitudes (>2500m), the effects of hypoxia and of cold and low humidity become more and more evident, so that asthmatics might be expected to worsen in this environment. Unfortunately, very limited information is available about the exposure of asthmatic subjects to high altitude and about the suitability of mountain climbing as an appropriate form of sport for asthmatics. The only two independent risk factors for asthma attacks at altitude identified in a paper by Golan  are: frequent use (> 3 times weekly) of inhaled bronchodilators before travel and participation in intensive physical exertion in the course of the treks.
At very high altitude the positive factors seem to prevail over the negative ones and the bronchial hyper responsiveness to both methacholine and hyposmolar aerosol is significantly reduced [1,11].
Was this article helpful?