How can Sulfur Dioxide (SO2) be detected apart from odor?

Sulfur Dioxide (SO2) can be detected through respiratory tract irritation because exposure to this gas causes immediate and noticeable effects on the respiratory system. Individuals often experience symptoms such as coughing, throat irritation, and shortness of breath when exposed to SO2, making it a practical and sensitive way to recognize the presence of this gas in the environment. The irritant properties of SO2 serve as a biological indication, alerting individuals to its presence even before advanced detection methods or instruments are employed.

While the other methods listed are used in various contexts for gas detection, respiratory tract irritation is particularly relevant to the immediate effects experienced by people, thus emphasizing the gas's impact on health and safety.