RESEARCH Individuals with increased u a

Full list of author information is available at the end of the articleBackground Ozone (O3) is an important criteria air pollutant known to induce exacerbation of asthma and other airway dis-eases [1,2]. Human challenge studies have shown that O3 exposure causes an immediate nociceptive decrease in lung function [3], increased airway hyperresponsiveness [3] and enhanced response to allergens in allergic volun-teers [4,5]. O3 also induces airway inflammation in healthy and asthmatic volunteers that is marked by inflammatory cell (i.e. neutrophil (PMN)) influx to the airways [6,7]. In healthy volunteers, the inflammatory response in the air-ways can occur at O3 levels near (0.08 ppm) or below (0.06 ppm) the National Ambient Air Quality Standard (NAAQS) for ambient O3 with noted variability across individuals, such that some are very responsive while others have a very weak inflammatory response, suggest-ing the presence of a inflammatory response phenotype i