The dangerous liaison between pollens and pollution in respiratory allergy

Objective To recapitulate the more recent epidemiologic studies on the association of air pollution with respiratory allergic diseases prevalence and to discuss the main limitations of current approaches used to establish a link between pollinosis and pollution. Data Sources Through the use of PubMed, we conducted a broad literature review in the following areas: epidemiology of respiratory allergic diseases, effect of pollution and climate changes on pollen grains, and immunomodulatory properties of pollen substances. Study Selections Studies on short- and long-term exposure to air pollutants, such as gaseous and particulate materials, on allergic sensitization, and on exacerbation of asthma symptoms were considered. Results Trend in respiratory allergic disease prevalence has increased worldwide during the last 3 decades. Although recent epidemiologic studies on a possible association of this phenomenon with increasing pollution are controversial, botanic studies suggest a clear effect of several pollutants combined to climatic changes on the increased expression of allergenic proteins in several pollen grains. The current literature suggests the need for considering both pollen allergen and pollutant contents for epidemiologic evaluation of environmental determinants in respiratory allergies. We propose that a measure of allergenic potential of pollens, indicative of the increase in allergenicity of a polluted pollen, may be considered as a new risk indicator for respiratory health in urban areas. Conclusion Because public greens are located in strict proximity to the anthropogenic sources of pollution, the identification of novel more reliable parameters for risk assessment in respiratory allergic diseases is an essential need for public health management and primary prevention area.