RESPIRATORY EFFECTS OF AIR-POLLUTION IN CHRONIC OBSTRUCTIVE PULMONARY-DISEASE - A 3 MONTH PROSPECTIVE-STUDY

Background - A study was undertaken to investigate the relationship be tween air pollution levels and respiratory symptoms and peak expirator y flow rate (PEFR) in subjects with chronic obstructive pulmonary dise ase (COPD) living in Christchurch, New Zealand. Methods - Forty subjec ts aged over 55 years with COPD completed twice daily diaries for thre e months during the winter of 1994. Subjects recorded respiratory symp toms, PEFR, outdoor activity, visits to doctor or hospital, and medica tion use. All were resident within a 5 km radius of the regional counc il's air pollution monitoring site. Daily and hourly mean pollutant le vels (particulates (PM10), nitrogen dioxide (NO2), sulphur dioxide (SO 2) and carbon monoxide (CO)) were measured at the monitoring site. Res ults - Pollution levels were generally low relative to those recorded in previous years. The New Zealand Ministry for the Environment guidel ines for PM10 were exceeded on five occasions, and for CO six times. N o association was found between PEFR and any of the pollution variable s. A rise in PM10 concentration equivalent to the interquartile range was associated with an increase in night time chest symptoms (relative risk 1.38, 95% CI 1.07 to 1.78). A rise in NO2 concentrations equival ent to the interquartile range was associated with increased reliever inhaler use (relative risk 1.42, 95% CI 1.13 to 1.79) and for 24 hour lag analysis with increased nebuliser use (relative risk 2.81, 95% CI 1.81 to 4.39). There was no increase in the relative risk of other sym ptoms in relation to pollution levels. Conclusions - These effects, de monstrated in a small susceptible group of subjects with COPD, indicat e that adverse outcomes can be measured in response to pollution level s that are within current guidelines.