* 280-320 mR/hr if you physically touched the bucket(s)
* 13.9 mR/hr if you were within 5 ft
* 1.85 mR/hr inside the building more than 5 feet away. Also can be thought of as "0 mR/hr above background"
* 2.02 mR/hr outside, in the park, on a bright sunny day.
2.02 is "background". i.e. the levels everyone is getting from natural sources outside.
13.9 mR/hr is 139 microsievert (µSv) per hour
So, really its that being near the buckets was 139 µSv/hr. A child would get ~70 µSv in that half hour, in theory.
If we believe Randall Munroe's (of xkcd fame) sourcing in https://xkcd.com/radiation/, then that means the kid got less than a round-trip flight from NY to LA sitting there for 30 minutes. "1400 times" sounds like one heck of a scare tactic. Not saying this was smart, but its overly alarmist.
Note also that GCNP contains all kinds of radiation sources. I was there with my wife a year ago doing some backcountry hiking.
We went in via Horseshoe Mesa. There are signs near the campground on Horseshoe Mesa warning you to stay out of areas where there was mining activity. We shoved on from there because our permit for the night was for further down rather than any concern about radiation.
More titillating is the warning in the backcountry hiking guide for the Tonto Trail from the Bright Angel Trail to the Hermit Trail:
"There is water in the bed of Horn Creek about half the time, but unfortunately it is radioactive so don't drink it unless death by thirst is the only other option. The source of the radioactivity is a deposit of high quality uranium contained within a collapsed cave system geologists call a breccia pipe." [0]
The milliroentgen values are probably wrong - 800 mR/hr would be way too much, something I wouldn't recommend touching :-).
The average background radiation is around 0.010 mR/hr - or 0.1µSv/hr.
* 280-320 mR/hr if you physically touched the bucket(s)
* 13.9 mR/hr if you were within 5 ft
* 1.85 mR/hr inside the building more than 5 feet away. Also can be thought of as "0 mR/hr above background"
* 2.02 mR/hr outside, in the park, on a bright sunny day.
2.02 is "background". i.e. the levels everyone is getting from natural sources outside.
13.9 mR/hr is 139 microsievert (µSv) per hour
So, really its that being near the buckets was 139 µSv/hr. A child would get ~70 µSv in that half hour, in theory. If we believe Randall Munroe's (of xkcd fame) sourcing in https://xkcd.com/radiation/, then that means the kid got less than a round-trip flight from NY to LA sitting there for 30 minutes. "1400 times" sounds like one heck of a scare tactic. Not saying this was smart, but its overly alarmist.
Numbers are from a picture I found. Scroll down a section on "Takeaways from the report" where it summarizes the exposure. https://www.azcentral.com/story/news/local/arizona/2019/02/1...