AARST_Radon_Reporter_July_2023

14 | July 2023 RESEARCH Before being sure of our conclusions, we needed to also rule out several possible confounding factors, including (1) a nonlinear response to concentration, which could be revealed by a different response to very high, or very low, concentrations, especially since there were some extremely high concentrations used in some chambers, (2) any change in the AlphaGUARDs response relative to one another during the intercomparison, and (3) a change in the AlphaGUARDs relative response when compared to the chamber concentration. (In other words, if one instrument started out at always running about 5% higher than the second instrument, but then gradually trended over time to the end of the study when it was running 20% higher than the second instrument, that would call into question the data from both instruments, without being sure which one, or if either, was correct.) First, did the AlphaGUARDs respond any differently at higher, or any differently at lower concentrations? To assess this, we plotted and calculated the slope of a possible linear relationship between the concentration and the RPE (% off of the benchmark) of each concentration. As is shown in Figure 2, there was no relationship at all, with a very flat slope close to zero. In other words, the AlphaGUARDs responses (counts registered in the instrument per disintegration in the chamber) were the same no matter if the concentration was close to zero, or over 40,000 Bq/m3 (over 1000 pCi/L). FIGURE 2. MEAN RPE FROM EACH CALIBRATION CHAMBER AND CHAMBER CONCENTRATION Did You Know? AARST is rebranding to Indoor Environments Association™ • AARST’s Board of Directors decided to rebrand to formally adopt work already started on chemical vapor intrusion and pursue efforts focused on other contaminants of concern in the built environment while maintaining significant attention to radon, the second leading cause of lung cancer. • Over the next year, the association’s website, logo, and public identity will change to align with the organization’s recently revised mission statement. • Revised Mission Statement: AARST is a nonprofit, professional organization of members who are dedicated to the highest standard of excellence and ethical performance of hazard identification and abatement of radon, chemical vapor intrusion, and other contaminants of concern in the built environment. The organization primarily strives to advance the interests of its members through developing industry standards, certifying technical proficiency, enabling advancement of public policy, and communicating health risks to the public. continued on page 16