Asthma is one of the most common diseases afflicting humankind and affects more than 300 million people worldwide. There is a wide variation in the prevalence of asthma among children and adults across the globe, and the clear reasons for such a variation are yet to be ascertained. In this special issue, we will focus on the global variations in the prevalence of asthma, host risk factors including genetic studies, other ‘omics’ studies, immunology, and nutrition as well as the environmental risk factors such as indoor and outdoor air pollution, occupational factors, viral infections, microbiome, hygiene hypothesis and old friends hypothesis among others. The strategies for mitigation in preventing or reducing the global burden of asthma will be another important focus.

Keywords: Asthma, global variations, host & environmental risk factors