NYC 9/11 Public Portal Document
14
114 Liberty St EPA background study of lower
Manhattan
AVERAGE 11 samples 11 pg/m^ 45 samples 3.6 pg/m^
FOR ALL
SAMPLES 100% 100% High outlier of 259 pg/m®
(both detects omitted, as per EPA
and non choice to omit this value
detects)
AVERAGE 7 samples 5.5 pg/m^ 34 samples 2 pg/m^
FOR NON
DETECTS 64% (arithmetic mean of 14 the 76% (arithmetic mean of % the
detection limit of 11 pg/m^) detection limit of 4 pg/m^)
AVERAGE 4 samples 20.85 pg/m 11 samples 8.7 pg/m
FOR
SAMPLES 36% (arithmetic mean of 17.2, 24% High outlier of 259 pg/m®
WHERE 19.6, 22.1,22.1) omitted, as per EPA
SILICA WAS assumption
DETECTED |
The chart below shows graphically the very marked difference in the distribution between the
silica concentrations found at the 114 Liberty building after the EPA cleaning and the EPA
background study. Two levels are given for both the 114 Liberty address, and also for the EPA
background study. The first value is 54 the detection limit in air, coupled with the percentage of
samples with levels below the detection limit. The second value is the average air concentration
for those samples where silica was detected, coupled with the percentage of these samples. As
can be seen, there is no similarity or significant overlap in the distributions whatsoever.
80%-T-
70%- -
60%- -
50%- -
40%- -
30%- -
20%- -
10%- -
0%' — 1
0 6 10 15 20 25
□ Midtown Manhattan Background ■ 114 Liberty j
EPA cannot revoke its silica criterion at 114 Liberty based on false contention that
background levels in NYC are already at unsafe levels
Even if silica background levels in midtown Manhattan are in fact above benchmarks, EPA
cannot excuse similar high levels at 114 Liberty and claim that it has no responsibility for
abating it. If EPA has in fact identified silica health risks in other NYC residences not impacted
NYC-WTC_000154989
OCR can misread numbers and units. Confirm readings against the page image before using them.