These levels of radiation are small and unlikely to affect human health. The longer you are on a flight, the more radiation you receive. The higher you are in altitude, the higher the dose of radiation. This is a result of less shielding of cosmic radiation by the atmosphere at higher altitudes.

The primary reason for increased radiation during flights is Cosmic Radiation, which consists of high-energy subatomic particles (protons and atomic nuclei) originating from deep space and our sun. On the ground, the Earth's thick atmosphere and magnetic field act as a massive shield, absorbing or deflecting the vast majority of these particles. However, commercial jets typically cruise at altitudes between 30,000 and 42,000 feet, where the atmosphere is much thinner and provides significantly less protection. At these heights, passengers and crew are exposed to a higher dose of "galactic cosmic radiation." The level of exposure also increases as you fly further from the equator toward the North or South Poles, as the Earth’s magnetic field lines funnel particles toward the poles. While a single transcontinental flight exposes you to roughly the same amount of radiation as a single chest X-ray (about 0.03 mSv), it is generally considered a low risk for casual flyers. For frequent flyers and flight crews, however, this cumulative "occupational exposure" is monitored, as they are technically classified as "radiation workers" by some health organizations due to the high volume of time spent at high altitudes.