Are airport scanners dangerous? The Transportation Safety Administration says absolutely not. But travelers have expressed their doubts, fearing that submitting to the scans will expose them to hazardous radiation.

There’s no need to worry, said Dr. Lewis Nelson, professor and chair of emergency medicine at Rutgers New Jersey Medical School. Radiation is a general term for different kinds of moving electromagnetic energy: ionizing radiation (what X-ray machines emit) and nonionizing radiation (which includes radio and magnetic waves). The key difference between ionizing and non-ionizing radiation is the level of energy they transmit. Ionizing radiation has enough energy to knock electrons away from atoms, creating free radicals; these chemically reactive particles can damage DNA and increase people’s risk of cancer. But ionizing radiation has a real impact on our health only when received at high doses. And in airport X-ray machines, even though about half of the scanners emit ionizing radiations, the dose just isn’t high enough to do bodily harm. While patients may be right to be concerned about the number of medical X-rays they receive, the amount of radiation delivered by an airport X-ray is tiny in comparison. A chest X-ray exposes patients to roughly 1,000 times the radiation of an airport scanner. These scanners emit such a tiny amount of radiation that even if you flew every day for a year, you’d still receive only a fraction of the ionizing radiation you absorb from food, based on dose estimates from NASA.

Most food contains small amounts of the radioactive molecules carbon-14 and potassium-40, according to NASA. In fact, many of the objects and substances we encounter daily emit radiation; the soil, cement sidewalks and buildings, and even the air we breathe are all slightly radioactive.