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The list of hazardous air contaminants
below were selected as the "Top 10" because they either exceed
Vermont's Hazardous Ambient Air Standard or they are of concern to the
public. To view bar graphs depicting measurement data of air toxics monitoring
data for the period 1996-2001, click on the name of the pollutant of interest.
| The list of hazardous
air pollutants above were selected as the "Top 10"
because they either exceed Vermont's ambient air standard or
they are of concern to the public. To view bar graphs depicting
measurement data for the period 1996-2001 associated with a
particular pollutant, click on a listed pollutant above. Ambient
monitoring data for mercury covers the period 1993-1997.
Note:
- The Burlington monitoring site was closed in mid-June
2000 due to the construction of a supermarket on the site,
but the APCD recommenced monitoring in Burlington on January
27, 2003 in the parking lot on the corner of South Winooski
and Main Street. To view the new monitoring site, please
click here.
- The urban air toxics monitoring site in Lyndonville
was added on 1/1/2001 and monitoring for VOCs and carbonyls
continued for one year, through February 2002. This site
is intended as a source-oriented styrene sampling site
but simultaneously serves as a population-oriented monitoring
site.
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To read about the status of air toxics monitoring in Vermont,
please click here.
Acetaldehyde
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Benzene
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1,3-Butadiene
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Carbon
Tetrachloride
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Chloroform
Greater than 90% of measured chloroform
concentrations were below the method minimum detection limit at all air
toxics monitoring sites in Vermont during the period 1996-2001. Therefore,
no bar charts are available. However, some monitoring data indicate that
levels of chloroform in the ambient air may exceed the Hazardous Ambient
Air Standard of 0.043 µ g/m3. For this reason, chloroform remains
a hazardous air contaminant of concern.
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Formaldehyde
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Methylene
Chloride
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Tetrachloroethylene
Greater than 90% of measured tetrachloroethylene
concentrations were below the method minimum detection limit at all air
toxics monitoring sites in Vermont during the period 1996-2001. Therefore,
no bar charts are available. However, some monitoring data indicate that
levels of tetrachloroethylene in the ambient air may exceed the Hazardous
Ambient Air Standard of 0.41 µ g/m3. For this reason, tetrachloroethylene
remains a hazardous air contaminant of concern.
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Mercury
Vapor Mercury
Particulate Mercury
The Hazardous Ambient Air Standard
for Mercury Compounds is 0.12 µg/m3, which is the same as 120
ng/m3 or 120,000 pg/m3 .
Measured concentrations of vapor and
particulate mercury combined are two orders of magnitude lower than the
HAAS. Nonetheless mercury was selected as a priority compound due to concerns
surrounding this contaminant on the state and national level.
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Styrene
* Ambient air concentrations of styrene
do not exceed the current Hazardous Ambient Air Standard (512 µg/m3).
Styrene was selected as a priority compound due to local public concern
regarding the adequacy of the current standard.
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Return to Air Toxics Program
Page
Last Updated: 2/4/03
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Air Pollution Control Division 
