Bathroom singing is a popular phenomenon
Is it healthy?
Bathroom singing
Bathroom singing, also known as singing in the bathroom, singing in the bath, or singing in the shower, is a widespread phenomenon. 
Many people sing in the bathroom because the hard wall surfaces, often tiles or wooden panels, and lack of soft furnishings, create an aurally pleasing acoustic environment. The multiple reflections from walls enrich the sound of one's voice. Small dimensions and hard surfaces of a typical bathroom produce various kinds of standing waves, reverberation and echoes, giving the voice "fullness
and forceful working mechanism to enforce the smoking ban." 
Chinese physicians and smoking.
Tobacco use has been identified as an increasingly popular phenomenon in China, and Chinese physicians have been found to exhibit high smoking rates as well. The practice is controversial because some believe that medical professionals should serve as role models of healthy behavior to their patients, while others believe that doctors should have the right to smoke because it is a personal matter.
Chinese physicians and smoking Prevalence.
A 2004 study conducted among 3,500 Chinese physicians