There is more up there than what my Gamma detector is picking up. Judging by the NAIRAS website, my detector is picking up 1/3 of the total ionizing radiation at flight altitude. This is the case in the northern latitudes north of about the 35 degree parallel. South of this, my meter seems to pick up most everything.
I’m trying to ascertain what types of radiation are up there so that I can get meters to measure the total spectrum. For now, though, when I’m up north, I have to simply multiply my reading by 3 to get an estimate of the total dose. This information is really sobering as I thought 4.0 uSv/hr was quite a high dose rate while flying over the Atlantic. The actual dose rate was around 12 uSv/hr!
I have also been searching for a dosimeter that pilots, flight attendants and frequent flyers can carry. I’ve concluded that one dose not exist…at least not one that is affordable. When I’ve figured out what types of radiation make up the majority of the spectrum, I’ll see what I can do about getting one constructed.
Still, the results I’m getting with my Polismart Gamma detector continue to be fascinating. And the ability to store the data, graph it and map it is, actually, quite amazing, considering how affordable the device is. I know, I’m biased because I’m beta testing it. But really, the Polismart has worked flawlessly and the App has exceeded my expectations. My hat is off to the Polimaster folks who designed this gadget. It’s really great.
So, finally, with all the flying I’ve done lately, I’d like to say that I’m getting a very firm grasp on where the radiation is and what you can do about it. What I’ve discovered, to date, can be summarized like this:
- Aircrew get more radiation than nuclear power plant workers.
- Aircrew are classified as radiological workers by the NCRP (National Center for Radiation Protection)
- On average, north of 35 degrees north-latitude, radiation increases rapidly above about 35,000′. Pilots who do not need to go higher than that, operationally, might as well stay at a lower altitude if they want to avoid high radiation levels.
- Altitude has little affect on the radiation level when flying at latitudes south of about 30 degrees north. I’ve seen almost zero variation between 35,000′ and 45,000′ when flying from 30 degrees all the way down to the equator.
- Flying over the North pole is the most hazardous of all. Radiation levels will normally be 12-18 micro-Seiverts per hour, at 40,000′. From 31,000′ upwards, the radiation level will double about every 6500′. Pilots need to check on solar flare activity because, sometimes, levels can exceed 100 uSv/hr.
- An affordable dosimeter, that accurately measures all of the different types of radiation at flight altitude, does not seem to be readily available. There is 3x more up there than just Gamma. I think the other main components are radioactive electrons, protons and X-Rays.
- Currently, the best prediction center, I’ve found, for flight radiation, is the NAIRAS website.
It’s time to take this to the next level and start including the sun’s solar flares into the equation and see if I can pick up the daily variations of flux. Because the real danger of upper altitude radiation comes from solar flares directed at Earth. Levels can exceed 150uSv/hr during the strongest flares. And that’s dangerous.