Exposure to inhalant allergens is associated with allergen-specific sensitization, a risk factor for the development of bronchial asthma, along with genetic and environmental factors. Early life exposure to mites increases the risk of sensitization and development of asthma in high-risk children. The same would occur with cat allergen levels inside the house and increased risk of sensitization in preschool and school. On the other hand, early contact with multiple microorganisms contributes to preventive immunomodulation by inducing tolerance to allergens. Climate change has been shown to increase the potency of allergenic pollens and the severity of exposure to fungi, which could partly explain the increase in allergic diseases in recent years. There is much evidence regarding exposure to allergens in sensitized asthmatic children and asthma exacerbation. It is essential to know which allergens the patient is sensitized to in order to implement environmental avoidance measures. This article summarizes an update on the mechanisms of sensitization to inhalant allergens in asthmatic children and its relationship with climate change and asthma severity. The main prevention measures, environmental control and the role of immunotherapy are also presented.