- " "Now, before we proceed further, we must protect you," Doc said. / He strode to the step-van and removed a yellow radiation suit. "Put this on," he said. / Marty locked the video camera and stepped into the suit. The night had become chilly and it felt good to add the extra layer of material. With the hood pulled up, he felt totally divorced from the rest of the world, like a deep-sea diver on the floor of the ocean. "
- —From Back to the Future by George Gipe (quote, page 57)
- Doc Brown: "Wha-what's this thing I'm wearing?"
- Marty: "Well, this — this is a radiation suit."
- — Doc Brown asking Marty what his older self was wearing, after seeing the tape.
A radiation suit was a yellow or white garment worn to prevent exposure to radiation. It consisted of a full body suit, with a large radioactive warning symbol printed on the back; gauntlets, bearing smaller radioactive symbols on the wrists; and a helmet with a breath filter and large flaps that enveloped the wearer. Emmett Brown used a white one when handling the plutonium he obtained. Any time he inserted a pellet into the fuel chamber of the DeLorean time machine, he would don the suit.
Doc had an extra yellow suit for Marty McFly which he wore during the plutonium procedure. Before Marty could take it off, the Libyans arrived and killed Doc, thus Marty kept it on all the way to 1955.
As he exited the vehicle after crashing into the Peabody family's barn, they believed him to be an extraterrestrial and shot at him — even when he took it off — because he had "mutated into human form", according to Sherman Peabody.
After escaping, he continued to wear the suit up to where he saw the undeveloped Lyon Estates. He changed into his vest and pants and hid the car.
Later, when he needed to convince his father George to take Lorraine to the dance, he put on the suit and attached to the belt a hair dryer (as a 'ray gun') and his Walkman (as a "brain-melting" torture device) to achieve the full effect of "Darth Vader".