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. Author manuscript; available in PMC: 2021 Jun 20.
Published in final edited form as: Sci Total Environ. 2020 Mar 21;722:137891. doi: 10.1016/j.scitotenv.2020.137891

Table 2.

Selected percentiles of fiber concentrations* in air samples taken during the demolitions of 25 abandoned residential dwellings without asbestos abatement, with values below LOD estimated using the Reverse Kaplan-Meier method**

Samples analyzed by Transmission Electron Microscopy (n=46)
Variable Phased Contrast Microscopy All fibers/cc (n=101) Phased Contrast Microscopy for subset of 46 samples All fibers/cc Asbestos fibers/cc Other fibers/cc
n (%) above LOD*** 54 (53%) 25 (54%) 2 (4%) 39 (85%)
Median 0.0012 0.0018 -- 0.0016
75th percentile 0.0022 0.0034 -- 0.0084
90th percentile 0.0097 0.0400 0.0001 0.0310
*

For comparison purposes, background levels in urban US areas in the 1990s (the last period for which data were reported) had a median concentration of 0.0016 fibers/cc [35] in a dataset where approximately 94% of samples were analyzed via TEM.

**

A single asbestos fiber was identified in each of two samples from two (8%) of 25 homes.

***

LODs ranged from 0.00038 to 0.5 fibers/cc for PCM, 0.000086 to 0.013 fibers/cc for TEM.