Let’s get something straight: humans do not immediately freeze, burn, or explode in the vacuum of space. Human skin is resilient enough to keep in temperature and pressure, so your blood won’t boil or ooze from the pores right away. However, inhaled air can expand and damage your lungs, your eardrums will swell, and the saliva in your mouth may boil. If you ever find yourself stuck in an erratic space station airlock, about to be exposed to the depressurized environment, be sure to close your eyes tight, expel all the breath from your lungs, and stick your fingers in your ears. You might be able to survive for up to three minutes without any permanent damage.
More from NASA’s The Human Body in a Vacuum page.