Purpose: Asthmatics are adversely affected by the presence of air pollutants, the concentrations of which can nowadays be measured. However, the utility of this information in clinical practice has not been defined in a group of asthmatics in stable condition. Our objective was to determine what impact the level of air pollutants had on the control of their asthma and the degree of airway inflammation.
Methods: We performed a cross-sectional study of adult asthmatics in stable condition. From the regional environmental authority, we obtained the concentrations of ambient nitric oxide (NO2), ozone (O3), suspended particulate matter up to 10 micrometers in diameter (PM10) and sulphur dioxide (SO2) at fixed geographical points. Disease control was assessed using asthma control test (ACT) scores, and airway inflammation using fraction of exhaled nitric oxide (FeNO) values. Correlation and linear regression studies were performed using ACT scores as the dependent variable.
Results: The study included 99 asthmatics, aged 39 years (SD 8), 55% women. Mean ACT value was 17.2 (SD 6.5), and FeNO 33.7 (SD 16). Of the pollutants studied, only NO2 was correlated with ACT scores (CC = 0.45, p < 0.001). We found no relationship between pollutants and airway inflammation. Multivariate analysis showed that ACT score was predicted by ambient air NO2 concentration and, to a lesser extent, mean FeNO.
Conclusions: Information on the concentration of ambient NO2 in our environment can help the clinician to interpret the evolution of asthmatic patients.