Somerset County Average 1999 NATA Modeled Air Concentrations Compared to Health Benchmarks
Pollutant
Modeled
Air Concentration (ug/m3)
Health
Benchmark (ug/m3)
Risk
Ratio
%
Contribution from
Major Sources
Area
Sources
On-road
Mobile Sources
Nonroad
Mobile Sources
Background
Acetaldehyde
1
0.45
3
2%
4%
49%
9%
36%
Acrolein
0.09
0.020
4
0.1%
17%
63%
20%
0%
Arsenic Compounds
0.00005
0.00023
0.2
11%
89%
0%
0%
0%
Benzene
1
0.13
9
0.2%
7%
41%
15%
36%
Bis(2-ethylhexyl)phthalate
2
0.42
4
0.02%
0.04%
0%
0%
100%
1,3-Butadiene
0.1
0.033
3
0.008%
1%
33%
19%
47%
Cadmium Compounds
0.00005
0.00024
0.2
9%
90%
0%
0.7%
0%
Carbon Tetrachloride
0.3
0.067
4
0.002%
0.2%
0%
0%
100%
Chloroform
0.08
0.043
1.8
2%
48%
0%
0%
50%
Chromium (hexavalent form)
0.0002
0.000083
2
7%
89%
4%
0.2%
0%
1,4-Dichlorobenzene
0.04
0.091
0.5
2%
98%
0%
0%
0%
1,3-Dichloropropene
0.08
0.25
0.3
0%
100%
0%
0%
0%
Diesel Particulate Matter
2
0.0033
542
0%
0%
43%
57%
*
Ethylene Dibromide
0.02
0.0017
14
0.03%
0.009%
0%
0%
100%
Ethylene Dichloride
0.04
0.038
1
0.8%
0.3%
0%
0%
99%
Ethylene Oxide
0.003
0.011
0.3
53%
47%
0%
0%
0%
Formaldehyde
2
0.077
20
0.8%
5%
31%
12%
51%
Methyl Chloride
1
0.56
2
0.03%
0.4%
0%
0%
100%
Naphthalene
0.05
0.029
1.7
2%
68%
24%
6%
0%
Nickel Compounds
0.0009
0.0064
0.1
4%
92%
4%
0.6%
0%
Perchloroethylene
0.2
0.17
1
0.3%
40%
0%
0%
59%
1,1,2,2-Tetrachloroethane
0.06
0.017
3
0.2%
0.5%
0%
0%
99%
Chemicals with risk ratios greater than or equal to 1 are
in bold.
Risk Ratios in italics are based on noncarcinogenic effects.
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.
