1. The 2020 International Conference on Pollution Prevention and Environmental Engineering  (ICPPEE2020), originally scheduled to be held in Xi 'an, China, from March 06 to 08, 2020, were changed to online conferences. 

2.   All authors and participants who participated in the ICPPEE2020  online conference, will enjoy a free of registration fee in aother offline conferences.

3.  The specific method of participation will be announced in late-February through the official website. Please pay attention.