ESSEX 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
2.3
0.45
5.2
<1%
6%
9%
4%
81%*
Acrolein
0.092
0.020
4.6
<1%
23%
16%
9%
52%*
Arsenic Compounds
0.00056
0.00023
2.4
3%
18%
9%
7%
63%
Benzene
1.7
0.13
13
<1%
12%
42%
14%
32%
1,3-Butadiene
0.14
0.033
4.2
<1%
<1%
52%
19%
29%
Cadmium Compounds
0.00015
0.00024
0.6
16%
51%
0%
<1%
33%
Carbon Tetrachloride
0.61
0.067
9.1
0%
<1%
0%
0%
100%
Chloroform
0.18
0.043
4.2
<1%
67%
0%
0%
33%
Chromium (hexavalent form)
0.00028
0.000083
3.4
46%
12%
7%
1%
34%
Cobalt Compounds
0.00009
0.00011
0.8
88%
12%
0%
0%
0%
1,4-Dichlorobenzene
0.16
0.091
1.8
<1%
71%
0%
0%
29%
1,3-Dichloropropene
0.23
0.25
0.9
0%
100%
0%
0%
0%
Diesel Particulate Matter
1.6
0.0033
474
0%
0%
45%
55%
0%
Ethylbenzene
0.53
0.4
1.3
1%
25%
52%
22%
0%
Ethylene Oxide
0.0072
0.011
1.2
5%
35%
0%
0%
60%
Formaldehyde
2.6
0.077
34
<1%
3%
12%
8%
77%*
Methyl Chloride
1.2
0.56
2.2
<1%
1%
0%
0%
99%
Naphthalene
0.2
0.029
7
<1%
49%
31%
4%
16%
Nickel Compounds
0.0013
0.0021
0.6
40%
45%
4%
4%
7%
PAH/POM
0.013
0.0072**
1.7
<1%
71%
13%
16%
0%
Perchloroethylene
0.35
0.17
2
<1%
81%
0%
0%
19%
1,1,2-Trichloroethane
0.000005
0.063
7.9E-5
60%
40%
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.
