Increased chronic obstructive pulmonary disease exacerbations of likely viral etiology follow elevated ambient nitrogen oxides

This study evaluated the characteristics of pollution-associated COPD exacerbations, and whether the effect of pollution on exacerbations differed according to likely exacerbation etiology (ie infective or non-infective); a total of 440 patients were included in the study. At the time of recruitment into the study, a medical history was taken for each patient, with lung function testing undertaken using a Vitalograph wedge bellows spirometer.