* My highest MAX reading in 2014–15 was at an unknown cruising altitude (from the look of the landscape below me, I should estimate we were no more than 35,000 feet) over the Great Salt Lake in Utah: 4.17 micros. My two highest one-minute SCALER measurements, taken over that same general area on two separate flights (one at unknown altitude, the other at 37,000 feet), tied at 3.3 micros. The next highest SCALER reading was 3.17, measured at 37,000 feet over Minsk, Belarus.