question:  What isn't a reason that it was foolish for Gwayne to leave the ship in such a hurry?
context: They were something more—and something less—they were, in short, humanity's hopes for survival! Captain Gwayne cursed and rolled over, reaching for his boots. The starlanes between Earth and her potential colonies were rough on the men who traveled them now. Gwayne swore softly to himself. Earth couldn't turn out enough starmen in the schools, so promising kids were being shipped out for training as cadets on their twelfth birthday. The two he'd drawn, Kaufman and Pinelli, seemed to be totally devoid of any sense of caution. But something had happened to the exploration party fifteen years back, and to the more recent ship under Hennessy that was sent to check up. Even the deep gorge where they'd found Hennessy's carefully buried ship was completely hidden by the fog. Earth had ordered him to detour here, after leaving his load of deep-sleep stored colonists on Official World 71, to check on any sign of Hennessy. If there was no sign in another day or so of what had happened to the men who'd deserted their ship and its equipment, he'd have to report back. He would have left before, if a recent landslip hadn't exposed enough of the buried ship for his metal locators to spot from the air by luck. Now the three were streaking at fantastic speed to a spot near the ship, to hover excitedly above something that moved there. It was too far to see clearly, but Gwayne grabbed the microphone, yelling into the radio toward the cadets. One seemed to be almost eight feet tall, leading the others directly toward the spacesuited cadets. One, at the front, was stuttering into life, and Gwayne dashed for it as the exit port slid back. At a gesture, the jeep rolled down the ramp, grinding its gears into second as it picked up speed. Then Gwayne spotted them; surrounded by the menacing horde. A spear crunched against the windshield from behind, and Gwayne caught it before it could foul the steering wheel.
output:  the air is dangerous for him to breathe
options:  the air is dangerous for him to breathe  he forgot to bring the radio  they didn't know for sure what was out there  he was outnumbered