SOMERSET County Average 2005 NATA Modeled Air Concentrations Compared to Health Benchmarks
Pollutant
Modeled
Air Concentration (ug/m3)
Health
Benchmark (ug/m3)
Risk
Ratio
%
Contribution from
Point Sources
Nonpoint
Sources
On-road
Mobile Sources
Nonroad
Mobile Sources
Background & Secondary
Acetaldehyde
1.8
0.45
3.9
0%
3%
4%
2%
91%*
Acrolein
0.044
0.020
2.2
<1%
17%
11%
11%
61%*
Arsenic Compounds
0.00043
0.00023
1.8
3%
7%
3%
4%
83%
Benzene
0.99
0.13
7.6
<1%
10%
22%
13%
55%
1,3-Butadiene
0.075
0.033
2.3
0%
<1%
29%
18%
53%
Cadmium Compounds
0.000086
0.00024
0.4
8%
29%
0%
<1%
63%
Carbon Tetrachloride
0.61
0.067
9.1
0%
<1%
0%
0%
100%
Chloroform
0.098
0.043
2.3
<1%
39%
0%
0%
61%
Chromium (hexavalent form)
0.00015
0.000083
1.8
24%
5%
4%
1%
66%
Cobalt Compounds
0.000029
0.00011
0.3
96%
4%
0%
0%
0%
1,4-Dichlorobenzene
0.088
0.091
0.9
<1%
47%
0%
0%
53%
1,3-Dichloropropene
0.079
0.25
0.3
0%
100%
0%
0%
0%
Diesel Particulate Matter
0.55
0.0033
167
0%
0%
49%
51%
0%
Ethylbenzene
0.19
0.4
0.5
1%
23%
40%
36%
0%
Ethylene Oxide
0.0088
0.011
0.8
2%
8%
0%
0%
90%
Formaldehyde
1.9
0.077
24
<1%
2%
5%
5%
88%*
Methyl Chloride
1.2
0.56
2.2
<1%
<1%
0%
0%
100%
Naphthalene
0.089
0.029
3.1
1%
39%
20%
5%
35%
Nickel Compounds
0.00042
0.0021
0.2
39%
30%
4%
4%
23%
PAH/POM
0.0094
0.0072**
1.3
<1%
82%
6%
12%
0%
Perchloroethylene
0.13
0.17
0.7
<1%
48%
0%
0%
52%
1,1,2-Trichloroethane
1.4E-6
0.063
2.0E-5
66%
34%
0%
0%
0%
Chemicals with risk ratios greater than or equal to 1 are
in bold.
Risk Ratios based on noncarcinogenic effects are in italics.
The symbol ug/m3 is micrograms per cubic meter,
the amount (in micrograms) of a chemical in a cubic
meter of air. This is also known as a concentration.
For diesel particulate matter, onroad and nonroad
concentrations include a model-estimated background
concentration. *Acetaldehyde, acrolein and formaldehyde concentration estimates include secondary formation, which is the process by which chemicals in the air are transformed into other chemicals.
**PAH/POM is "polycyclic aromatic hydrocarbons/polycyclic organic matter." These define a broad class of compounds. The chemicals making up this class were broken up into 8 groups based on toxicity, and each group was assigned a cancer-weighted toxicity estimate. 0.0072 ug/m3 is the health benchmark average across the 8 groups.
