Most negative ion generators will produce ozone, especially the needle release type. The odor value of ozone is relatively low, generally around 0. 1ppm. It can be opened in a closed space to see if there is obvious ozone odor, which is similar to disinfectant water and fishy smell, and has certain irritation. If you stay in the ozone environment for a long time, you will have a certain sore throat and dry eyes, which will stimulate the respiratory tract. Occupational exposure limits is 0.3 mg/m? .