No, it just compares the radiation exposure to dental and chest X-rays. You may be commingling roentgen with rad. If not, please excuse my insert of a clarification. Ionization in air (roentgens) and the absorbed dose in tissue (rads). In soft tissue they are almost equivalent. At least I believe that's correct. I'm by no means an expert in this field.
The NRC has established standards that allow exposures of up to 5,000 mrem per year for those who work with and around radioactive material, and 100 mrem per year for members of the public. That's 5,000,000 urem and 100,000 urem per year, if I've got my metric correct. The chart refers to uR per hour, which can add up in a year's time of frequent flying. The link below is to a Personal Annual Radiation Dose Calculator. However, it only goes to 9,000 ft elevation, but is included here for the reference.
http://www.nrc.gov/about-nrc/radiation/around-us/calculator.htmlIt's important to note that
permissible does not mean safe. The units for estimating impacts of radiation on living tissues--rads, rems and millirems--are based on models and assumptions. Exposure to radiation increases the risk of damage to tissues, cells, DNA and other vital molecules--potentially causing programmed cell death (apoptosis), genetic mutations, cancers, leukemias, birth defects, and reproductive, immune, cardiovascular, and endocrine system disorders. The varying impacts on health of each of the hundreds of different nuclides to which people may be exposed are simply not known.
Since scientists do not truly know the specific impacts a given radionuclide may have on the organs and tissues of a specific person, the translation of the amount of radioactivity to which that person has been exposed (in curies or fractions of a curie) into a radiation dose (in rems or millirems) is basically speculation.
Note also that the true dose from the In-flight Radiation Dose Rates chart is not known, as only two types of radiation were measured.
Here's the full text of the article.
RADS ON A PLANE--THE RETURN FLIGHT: Regular readers of Spaceweather.com have been following the travels of Tony Phillips, who spent the past week flying commercial jets back and forth across the USA for meetings in Washington DC. In addition to his usual baggage, he carried a pair of radiation sensors onboard. Sitting in the economy section of a US Airways flight from Reno to Phoenix on Nov. 11th, Phillips recorded dose rates which were almost 30 times higher than background dose rates at ground level. On Nov. 15th, he gathered data from a return leg, American Airlines flight 2407 from Washington DC to Chicago. It was only half as bad:
The radiation inside these planes comes from space--that is, cosmic rays that penetrate Earth's atmosphere and reach down to aviation altitudes. In the plot we can see what a difference altitude makes: Cruising at 39,000 feet, the Reno to Phoenix flight was closer to space and thus experienced double the radiation of the DC to Chicago flight cruising at 28,000 feet.
The radiation sensor Phillips used to make these measurements is the same one that Earth to Sky Calculus routinely flies onboard helium balloons to measure cosmic rays in the stratosphere. It detects X-rays and gamma-rays in the energy range 10 keV to 20 MeV, similar to energies used by medical X-ray machines and airport security scanners.
We can put these doses into context by comparing them to medical X-rays. In a single hour flying between Reno and Phoenix on Nov. 11th, the passengers were exposed to about the same amount of radiation as an X-ray at the dentist's office. Such a dose is not a big deal for an occasional flier, but as NASA points out, frequent fliers of 100,000 miles or more can accumulate doses equal to 20 chest X-rays or about 100 dental X-rays. Lead aprons, anyone?
Some experts reading these reports on Spaceweather.com have pointed out that X-rays and gamma-rays represent only a fraction of the radiation present at aviation altitudes. The true dose could be doubled or tripled by neutrons, a component of cosmic rays known to be especially good at delivering energy to human tissue.
