Which Population Level Environmental Factors are Associated with Asthma, Rhinoconjunctivitis and Eczema? Review of the Ecological Analyses of ISAAC Phase One

M Innes Asher; Alistair W Stewart; Javier Mallol; Stephen Montefort; Christopher KW Lai; Nadia Aït-Khaled; Joseph Odhiambo


Respiratory Research. 2010;11(8):8 

In This Article


ISAAC has explored environmental factors at a population level which may relate to the prevalence of asthma, rhinoconjunctivitis and eczema while recognising the limitations of the ecological approach in causal inference at the individual level. Some global associations which could be explored by further research were positive associations between the prevalence of symptoms of asthma, rhinoconjunctivitis and eczema in populations and GNP, trans fatty acids, paracetamol, and women smoking and inverse associations between food of plant origin, pollen, immunisations, tuberculosis notifications, air pollution, and men smoking, and some showed mixed effects (antibiotics and climatic factors). While the global ecological approach has advantages, it may miss factors of importance within regions, and involving combinations of variables within or between regions. ISAAC Phase Three has extended research in the areas identified in this review using an environmental questionnaire which enables some of these hypotheses to be explored further with individual level as well as ecological analyses. Further studies could include randomised controlled trials of putative risk factors such as paracetamol exposure. Since these ecological studies took place, globalization has introduced further large environmental changes. Rapid environmental and lifestyle changes within whole societies offers potential opportunities for demonstrating the importance of community-wide determinants of ill-health, and provides a rationale for monitoring time trends in asthma and allergic diseases in diverse populations, as in Phase One centres that also participated in ISAAC Phase Three.


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