More than 100 canisters of tear gas were used in Saturday night's riot in East Lansing.
Tear gas can cause a variety of symptoms including burning skin, blurred vision, and vomiting. The symptoms usually disappear within several hours. The severity depends on the dose amount and how sensitive the person is.
Dr. Lawrence Fischer, an environmental toxicologist with MSU, said in rare cases, the gas can be very dangerous.
"It's been reported to cause asthma attacks in people who are prone to asthma, and in people who have bad asthma, and aren't able to get treatment quickly, you could die."
If exposed, get to clean air immediately and wash the contaminated clothes. The best way to get the gas off skin is to use a scrub. Soap typically isn't that effective.
Sparrow Hospital treated about 20 patients Saturday night for tear gas exposure. They were given deep-contamination washes and treated for breathing problems.