You may notice a strange odor for a short time. This is because the UV-C light irradiates everything in the device, including the dead skin cells that occur in the air. These skin cells contain natural oil. What you may smell after using the device are the volatile organic compounds that were released when the skin cells in the air were irradiated by the UV-C. UV-C does NOT cause toxic by-products. Once the timer has expired and the blue indicator light goes out, the device can be opened safely. You don't need to wait.
There are several ways you can tell:
1. Whether the COBstr Box is switched on or not can be seen by the blue indicator light that lights up when the COBstr Box is in operation.
2. Does disinfection actually take place? Read about it on the page with measurement results.
3. With a dosimeter. This is a card that measures UV-C radiation.
4. You can also carry out experiments yourself. For example, people use the green banana test to check whether it is actually UV-C light. When (working) UV-C light hits a banana, it will turn brown. You can also take a look at this video..