When most of us think about radiation (and let’s be honest, most of us don’t think about it much at all) we normally think of microwaves and X-ray machines. But it turns out, there’s another type of radiation most of us aren’t even aware of—cosmic radiation. It’s something we’re all exposed to on a daily basis, but even more so when we’re on an airplane. So, what is cosmic radiation and how worried should we be about it when we’re flying?
If the term ‘cosmic’ makes you think of #cosmicvibes and astrology, you’re not that far off the mark. Also known as ionic radiation, cosmic radiation is the energy particles from outer space, produced by the stars and our sun. These rain down on earth constantly, but our atmosphere acts a radiation shield, providing a layer of protection. While some of this radiation does make it to earth, the exposure at ground level is very low—especially in Australia, where we have the lowest elevation of any continent.
However, when our altitude increases (aka. when we’re on a plane), so does our exposure to cosmic radiation. This is particularly the case during the period of flight cruising, as this is when altitude peaks. The flight duration and latitude–the distance from the equator–also impact your exposure to cosmic radiation on flights.
The radiation dose on a typical commercial airline flight altitude is about 0.003 millisieverts (mSv) per hour. While this is slightly higher than the exposure at ground level, it’s extremely minimal. Whether or not you fly, the average person’s dose of cosmic radiation is 0.33 mSv or 11% of our yearly exposure to all natural sources of radiation.
But what about frequent flyers or people who fly for a living? Large studies into the health of pilots and aircrew have shown no increased risk of cancer as a result of frequent exposure to cosmic radiation. According to the Australian Radiation Protection and Nuclear Safety Agency, exposures of aircrew to cosmic radiation are typically less than a quarter of the occupational dose limit of 20mSV—and this is similar to airlines across the world. Meanwhile, people who fly very frequently, for example, 10-20 hours per week on long-haul flights, would be looking at around a 1mSv per year dose.
So, even if you’re in the sky on a weekly basis, your exposure to cosmic radiation isn’t cause for concern. The only time you should be concerned is if you happen to be an astronaut travelling outside the earth’s atmosphere. Exposure to radiation is very high in these scenarios and it’s one of the things that has stopped us inhabiting other planets like Mars!
At the end of the day, we are all exposed to background radiation on a daily basis—it’s in the water we drink, the food we eat, the homes we live in and the devices we use. But much like cosmic radiation, the exposure is so minimal that there’s no known risk of cancer. Bar any nuclear disasters, the highest dose of radiation comes from undergoing regular medical imaging (ie. X-rays and CAT scans), but it’s widely accepted that the medical benefits outweigh the risk.