* But there were sunnier ways to calculate those 23.2 micros. Magill’s Survey of Science, published in 1993, advised me that “those working with radiation are required to keep their dosage below 5 rems [= 50 millis] per year, which is . . . 25 microsieverts . . . per hour for a 40-hour work week. No ill effects have been observed at several times this dosage.”