How to get rid of the smell of the toilet drain

There are three original classifications of the odor return of the bathroom waterway: 1. The toilet water pipe is tightly sealed, the toilet water connector sealing gasket is connected with the cast iron or UPVC pipe, and the toilet bowl is dismantled or smelled to be sealed and installed with putty or fireproof mud, and the toilet is glued around the toilet and the surface of the mouth for two seals. Check the smell channeling phenomenon of the exhaust fan check valve in the bathroom, and focus on the toilet-like situation, the sewage well and the well-like situation, and the second or third situation.