The Maryland episode is hardly the first time that a student or professor at an overseas university has provoked complaints back in China. Earlier this month, for example, a lecturer from Monash University in Australia was suspended after a Chinese student complained on Weibo of a classroom quiz that had appeared to insult Chinese officials.

In 2010, the University of Calgary announced that China’s Education Ministry had removed it from its list of accredited overseas institutions. The decision came weeks after the Canadian university had awarded an honorary degree to the Dalai Lama, whom the Chinese government accuses of promoting Tibetan independence from China.

A planned speech next month by the Dalai Lama at the University of California, San Diego, has already prompted the local chapter of the Chinese Students and Scholars Association to threaten “tough measures to resolutely resist the school’s unreasonable behavior.”

In her speech on Sunday, Ms. Yang said she had been relieved to find that she did not need to wear any of her five pollution masks in the United States. She also discovered, she said, that the freedoms enshrined in the Declaration of Independence were not the abstractions she had once imagined.

“Democracy and freedom are the fresh air that is worth fighting for,” she said.

But critics on social media skewered the address. Some took to Facebook and Weibo to challenge Ms. Yang’s comment about pollution masks:

One Facebook user, Sincerlia Yang, commented: “This is the real KunMing TODAY! Shuping Yang do you need five masks?”

Other users objected to Ms. Yang’s general tone.

“Our motherland needs a lot of improvements, but it’s still the motherland,” the Weibo user Guaishoukankan wrote in a typical comment. “There are different types of social issues and discrimination in the U.S., too.”

Still others cursed at Ms. Yang, or said that she would not be welcome in China.

In a statement that did not directly address the uproar, the University of Maryland said on Monday that it “proudly supports Shuping’s right to share her views and her unique perspectives.”

“The university believes that to be an informed global citizen it is critical to hear different viewpoints, to embrace diversity, and demonstrate tolerance when faced with views with which we may disagree,” the statement added. “Listening to and respectfully engaging with those whom we disagree are essential skills, both within university walls and beyond.”