Answer: The accident caused radioactive gases to be released into the atmosphere.
Step-by-step explanation:
In March, 1979, there was a nuclear accident at the Three Mile Island where a nuclear reactor suffered a partial meltdown. Even though things could have been worse, it was not significant to the point of human casualties.
It did however result in the release of radioactive gasses such as Xenon and Krypton. The accident led to increased regulation for the nuclear industry as people were concerned about a few event being much worse.