Environmental Report or Report on Environment

Dear teachers,

Regarding the following sentence:

"The biennial report on environment estimated that Seoul, Beijing, and Mexico are experiencing the worst air pollution."

(1) Can I say both "The biennial environmental report" and "The biennial report on environment"?

(2) I think the above mentioned sentence should be all in past tense as seen in the below:

"The biennial report on environment estimated that Seoul, Beijing, and Mexico were experiencing the worst air pollution."

What do you think of this?

Thanks and best regards,

David Kim