"The U.S. Institute for Energy Quantity Analysis has published a report that glass tumblers should be used at least 15 times, plastic tumblers at least 17 times, and ceramic tumblers at least 39 times. In addition, tumblers, which are made to replace disposable cups, emit much more greenhouse gases than disposable cups in all processes."  

​This is the statistics of basis that suggests the number of tumblers should be used.  

Considering that tumblers can be used for at least a year, if there is an environmental pollution prevention effect when used daily for two months, isn't this not a fully practicable amount?

Humans have the characteristic of taking a certain amount of water every day, and using tumblers instead of disposable cups will have environmental pollution prevention effects.