From Ministry Of Health & Family Welfare Guidelines:

4.1. Persons having no symptoms are not to use mask
Medical masks should not be used by healthy persons who are not having any symptoms
because it create a false sense of security that can lead to neglecting other essential measures such as washing of hands.
Further, there is no scientific evidence to show health benefit of using masks for non-sick persons in the community. In fact erroneous use of masks or continuous use of a disposable mask for longer than 6 hours or repeated use of same mask may actually increase risk of getting an infection.
Remember,a mask should only be used by health workers, caretakers and individuals with respiratory symptoms,such as fever and cough.

The following measures ARE NOT effective against COVID 2019 and can be harmful:
•Smoking
•Wearing Multiple Masks