1. The problem statement, all variables and given/known data Is there any way we can measure the thickness of an exposed PTFE membrane air sampling filter? An unexposed filter (from the filter datasheet) has a thickness of 40μm. We have 5 ambient air exposed filters with the following mass concentrations: 1μg/m3 (filter 1), 20.1 μg/m3 (filter 2), 40.6 μg/m3 (filter 3) , 60.1 μg/m3 (filter 4) , and 66.1 μg/m3 (filter 5) . Also, for each filter, we performed a procedure where we transmit a 1460 lux constant light source through the filter and the reduced light intensity was captured by a light sensor. The data for that procedure are as follows: CONTROL - 1460 LUX FILTER 1 - 418 LUX FILTER 2 - 375 LUX FILTER 3 - 295 LUX FILTER 4 - 185 LUX FILTER 5 - 130 LUX Btw, this is for our research. We try to determine the attenuation coefficient of each filter. Thank you very much! 2. Relevant equations I1d12 = I2d22 3. The attempt at a solution Does the above equation possible to use?