At what concentration in parts per million (PPM) can chlorine gas be detected by smell?

Chlorine gas can typically be detected by smell at a concentration of around 3 PPM. This detection threshold is important for safety and operational awareness in water treatment environments, as personnel need to be alert to the presence of this gas, which can be hazardous at higher concentrations. The olfactory response to chlorine is an early warning, allowing individuals to take precautions or evacuate the area if necessary. Recognizing this odor threshold is essential for operators to maintain a safe working environment and to monitor chlorine levels in water treatment processes.