A new procedure to validate and optimize 210Po measurements in atmospheric aerosols

Abstract

The exposure to air fine aerosols can cause health effects due to inhalations of alpha emitters such as ²²²Rn daughters. Lead-210 and ²¹⁰Po are mainly associated to aerosols with median aerodynamic diameter lower than 1 μm. The ²¹⁰Po is characterized by having a high radiotoxicity. The precise measurement of ²¹⁰Po in surface air aerosols is usually quite complex due to the significant contribution of the ²¹⁰Pb on their concentrations. Additionally, there is no possible means to manufacture a certified material to validate the measurements of ²¹⁰Pb and ²¹⁰Po concentrations in surface air aerosols. For these reasons, this study aims to develop a novel and comprehensive methodology to validate ²¹⁰Po measurements in surface air aerosols by preparing in our laboratory “standard samples” with known activities of both ²¹⁰Pb and ²¹⁰Po. A detailed sensitivity analysis on the precision of ²¹⁰Po concentration measurements has been carried out as a function of the involved variables such as sampling time, time elapsed between the sampling start and ²¹⁰Po self-deposition and the ²¹⁰Po/²¹⁰Pb activity ratio in surface air aerosols. This study is necessary to find the optimum conditions for a precise measurement of ²¹⁰Po in surface air aerosols. In addition, this methodology has been applied for the determination of ²¹⁰Po concentrations in 30 samplings campaigns of atmospheric aerosols carried out at the El Carmen campus (Huelva province) from March 25th to July 15th, 2022. The results obtained for ²¹⁰Pb and ²¹⁰Po concentrations and atmospheric aerosol residence times (via ²¹⁰Po/²¹⁰Pb activity ratio) were consistent with other previous works.