MIDDLESEX COUNTY
Middlesex County Average 2014 NATA Modeled Air Concentrations
Compared to Health Benchmarks |
Pollutant |
Modeled
Air Concentration (ug/m3) |
Health
Benchmark (ug/m3) |
Risk
Ratio |
%
Contribution by Source Category |
Point Sources |
Nonpoint Sources |
Onroad
Mobile |
Nonroad
Mobile |
Background& Secondary |
1,3-Butadiene |
0.04 |
0.033 |
1 |
0% |
19% |
54% |
24% |
3% |
Acetaldehyde |
0.97 |
0.45 |
2 |
0% |
3% |
7% |
3% |
87%* |
Benzene |
0.55 |
0.13 |
4 |
1% |
26% |
47% |
24% |
2% |
Carbon tetrachloride |
0.55 |
0.17 |
3.2 |
0% |
0% |
0% |
0% |
100% |
Chromium (hexavalent form) |
0.000031 |
0.000083 |
0.3 |
68% |
28% |
1% |
3% |
0% |
Diesel Particulate Matter |
0.57 |
0.0033 |
172 |
0% |
0% |
58% |
42% |
0% |
Ethylene oxide |
0.00026 |
0.00043 |
0.6 |
81% |
19% |
0% |
0% |
0% |
Formaldehyde |
1.2 |
0.077 |
15.5 |
1% |
5% |
8% |
4% |
82%* |
Hydrazine |
0.00005 |
0.0002 |
0.25 |
100% |
0% |
0% |
0% |
0% |
Naphthalene |
0.04 |
0.029 |
1.37 |
10% |
28% |
45% |
9% |
8% |
Nickel Compounds |
0.00052 |
0.0021 |
0.24 |
32% |
17% |
9% |
42% |
0% |
Nitrobenzene |
0.0000004 |
0.025 |
0.000016 |
62% |
38% |
0% |
0% |
0% |
Tetachloroethylene |
0.026 |
0.17 |
0.15 |
16% |
84% |
0% |
0% |
0% |
Vinyl chloride |
0.0008 |
0.11 |
0.007 |
100% |
0% |
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. |
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