How does SO2 affect people with asthma?
SO2 is a highly water-soluble gas that, when inhaled, is almost entirely absorbed by the mucous membranes in the nose and upper airways. These membranes effectively reduce the level of inspired SO2 to approximately 2% of the initial inhaled concentration, which helps to protect lower airways from significant exposure. During situations like exercise that increase the breathing rate and the volume of inspired air, a greater amount of SO2 reaches the lower airways. Asthmatic individuals may react to these seemingly minimal increases in SO2 reaching lower airways whereas people without asthma do not. This is because people with asthma have a tendency to develop an exaggerated airway response to a wide variety of non-specific stimuli. This reaction can take the form of chest tightness, shortness of breath, cough or wheezing and may lead to disruption of activity, and/or the need for medication. What levels of SO2 cause symptoms for some exercising asthmatics? Please see the chart below. Ho
