Which of the following methods can be used for detecting Nitrogen Dioxide (NO2)?

Using a multi-gas detector is the appropriate method for detecting nitrogen dioxide (NO2) because these devices are specifically designed to measure various gases, including NO2, in the environment. Multi-gas detectors often come equipped with sensors capable of identifying multiple hazardous gases simultaneously, enabling operators to monitor air quality in real-time, which is crucial for maintaining safety in environments where gases like NO2 may be present.

Other detectors like carbon monoxide detectors, nitrogen oxide detectors, and hydrogen sulfide detectors are focused on specific gases. Carbon monoxide detectors are specialized for detecting carbon monoxide rather than nitrogen dioxide. Nitrogen oxide detectors may not provide accurate or comprehensive readings for all nitrogen compounds, including NO2, as they may focus on other nitrogen oxides. Hydrogen sulfide detectors are tailored to sense hydrogen sulfide gas specifically and would not be effective for NO2 detection. Thus, a multi-gas detector stands out as the best choice for identifying nitrogen dioxide among the options provided.