AARST_Radon_Reporter_July_2023

16 | July 2023 RESEARCH Second, were there any changes in the relative responses between the instruments, over time especially as the study went on so long (due to delays caused by the pandemic)? To assess this, we calculated the ratio of each AlphaGUARD relative to the average of the other two, over time, as shown in Figure 3. This analysis shows that the slope of the response of each instrument relative to the average of the other two is also close to a flat zero, indicating that each instrument had a consistent response throughout the entire study (at least relative to the other two). Note that chamber F’s individual instrument results are significantly different, but on average chamber F performed as well as others, and chamber F’s data do not affect the trend line. To illustrate this, Figure 4 plots the same data without chamber F. FIGURE 3. RATIO OF EACH ALPHAGUARD TO THE MEAN OF THE OTHER TWO FIGURE 4. RATIO OF EACH ALPHAGUARD TO THE MEAN OF THE OTHER TWO, WITHOUT CHAMBER F As shown in Figure 4, the slope of the linear relationship between the ratio of each instrument relative to the mean of the other two is essentially zero, indicating that over time there was no drift in relative response between the three AlphaGUARDs. Finally, the three traveling AGs were exposed in an outdoor environment (tent), within which they were encased in three layers of 0.1 mm plastic. Three sets of such exposures were conducted, and their results are shown in Figure 5.