Why must schools test with exterior doors and windows closed except for normal entry and exit?
The purpose of having exterior doors and windows closed is to get a more accurate, reproducible radon test result. If doors and windows are open, radon levels will fluctuate unpredictably depending on air pressure (if it’s a windy day, for example, a classroom with open windows may become depressurized or pressurized, causing radon levels to rise or fall, depending on the direction of the wind and other factors). 23. EPA recommends postponing tests if major weather or barometric changes are expected. What criteria should be used to define ‘major’ changes? In other testing guidance, for residential testing, EPA suggests that tests lasting two or three days should be postponed if storms with high winds, such as 30 miles per hour, or rapidly changing barometric pressure, are predicted during the measurement period. For longer tests, unusual weather conditions lasting a short time are less of a concern. In general, the more unusual the weather during the testing period, the more atypical t
