I’m a retired (well, semi) radiologist so radiation has been part of my career. By the time I went to med school (‘70s) the health physics and bioeffects folks had long before figured out how to keep us safer. Digital radiography = lower doses. CT and MRI = reduce the number of examinations needing X-rays (CT replaced a LOT of high-radiation and very unpleasant exams, particularly brain imaging). Still wore lead aprons and vests for fluoroscopy and I did mostly ultrasound (but did some alongside my colleagues doing the fluoroscopy). I’ve also had a life-long interest in aerospace stuff and this is where my interest in history of this stuff came into play. Radium-painted aircraft instruments I knew about (and have read the postings on this), but I discovered that a lot of aerospace stuff - including some of the Apollo program hardware - was made using a thoriated magnesium alloy. Because I collect this stuff, I keep a calibrated survey meter at home. A couple of my Apollo items are “hot” - a power and servo assembly from the Command Module and a Coupling Data Unit (also from the CM). I sent a question to the Thorium Alliance and they provided a lot of information - there’s not a lot of thorium in magthor alloys and radon emission is also near nil (that was my concern). Even so, the two hot items live in gasketed airtight mil-spec transit cases. My radium-painted aircraft instruments are stored in surplus ammo boxes. None stay in our most frequently-occupied living areas. I’ve also encountered radioactive optics from rare-earth glasses and some with thorium tetroxide optical coatings. Pretty low dose rates from these though. A lot of WW II aerial camera lenses used radioactive glass and some radium paint was used in instruments that might be unexpected. Most of the WW II aircraft bubble sextants had radium paint in a ring around the bubble chamber for backup in case the battery-powered lamp failed. I see these sold all the time with no warning at all about the radium paint. Probably OK so long as you don’t disassemble them. I didn’t know about the radioactive sparkplugs, but there’s a lot of other historical radioactive stuff out there.
