Urban air pollution is a serious public health hazard and has been associated with exacerbations of chronic respiratory illnesses due to airway mucus membrane irritation and increased oxidative stress. However no convincing link between air pollution and allergic sensitisation has been shown in the scientific literature. We know that nitrogen dioxide, ozone and diesel exhaust particulate matter in air pollution can predispose to increased respiratory infections, aggrevate asthma, bronchiectasis and chronic bronchitis (COPD), but any link to actually triggering allergic sensitisation is less clear. Certainly diesel exhaust particles have been shown to absorb grass pollen grains and increase the pollen load in the nose and lungs, thus making hay fever and hay asthma symptoms worse for city dwellers and those living near motorways.
Reference: Kelly FJ, Fussell JC. Air pollution and airway disease. Clinical and Experimental Allergy 2011 (41) 1059-1071
