Which is NOT a symptom of exposure to hydrogen chloride?

Hydrogen chloride exposure is primarily associated with respiratory and skin symptoms due to its corrosive nature. Common symptoms of exposure include skin irritation from contact and respiratory distress, such as a dry throat and shortness of breath, which can occur as the gas affects the mucous membranes of the lungs and throat.

While mild headache can sometimes be associated with various types of exposure or environmental factors, it is not a direct or well-documented symptom of hydrogen chloride exposure specifically. Therefore, it is more accurate to consider dry throat, skin irritation, and shortness of breath as primary symptoms associated with this hazardous substance, distinguishing mild headache as less relevant in this context. This understanding reinforces the importance of awareness of specific symptoms related to chemical exposures for effective safety and health measures.