With the levels of outdoor air pollution from industrial and motor vehicle emissions rising rapidly in the fastly-industrializing countries of South East Asia, the prevalence of asthma and allergic diseases has also been increasing to match those in the West. Epidemiological and experimental exposure studies indicate a harmful impact of outdoor air pollution from vehicles and factories both on the development of allergic diseases and asthma and the increase in asthma symptoms and exacerbations. The level of outdoor pollution in Asia is much higher and more diverse than those encountered in Western countries. This may increase the impact of outdoor pollution on health, particularly lung health in Asia. This review discusses the constituents of air pollution in Asia with a special focus on studies in mainland China and Taiwan where the levels of pollution have reached high levels and where such high levels particularly in winter can cause a thick haze that reduces visibility. The onus remains on regulatory and public health authorities to curb the sources of pollution so that the health effects on the population particularly those with lung and cardiovascular diseases and with increased susceptibility can be mitigated.
