Air pollution can trigger asthma and, in severe cases, has been associated with hospitalisation and death. How much of a problem is air pollution though? What proportion of asthma exacerbations are due to air pollution each year? How much does this vary with extreme events such as bushfires and dust storms? This paper discusses the challenges associated with this type of monitoring, outlines the work that has so far been done in Australia in this area and presents a method for estimating the contribution of air pollution to asthma hospitalisations. The method has been applied to a particular case study 'Melbourne in 2006' to test its potential usefulness.