Ambient Air Toxic Monitoring

Vermont Air Toxics Monitoring Network Summary - 2002

The Vermont Air Pollution Control Division (APCD) has been monitoring a battery of toxics in the ambient air at several locations in the state since 1993 (see network map). The toxics monitored include volatile organic compounds (VOCs), carbonyls, metals and semi-volatiles. Vermont APCD collects pressurized whole-air 24-hour integrated ambient air samples in SUMMA-treated stainless steel canisters for VOCs per TO-15 every 12 days. Chemical analysis of VOCs is performed by the Urban Air Toxics Monitoring Program (UATMP) contractor, ERG. Analysis entails a cryogenic sample concentration system followed by GC/MS. There are approximately 58 UATMP target compounds, a few of which are benzene, 1,3-butadiene, toluene, xylenes, and styrene. To view a picture of ambient air monitoring equipment, please click here.

Vermont also monitors for 15 carbonyls on a 24-hour every 12 days sampling schedule. The sampling method used for carbonyls is TO11A. Some of the more important carbonyls measured include formaldehyde, and acetaldehyde. In the past year, it has become clear that TO11-A is insufficient for the monitoring of acrolein and crotonaldehyde. We are currently attempting to address this issue through the Northeast States for Coordinated Air Use Management (NESCAUM) and other means.

Metals are collected by total suspended particulate method (TSP) sampling on quartz fiber filters at all existing sites, except Lyndonville, on a 24-hour 12 days schedule as well. Sample analysis is by neutron activation analysis for metals such as arsenic, cadmium, and chromium. Lead and beryllium are quantified by graphite furnace atomic absorption spectroscopy.

Vapor and particulate mercury samples have been collected at the Underhill site since 1992, providing the longest continuous event sampling mercury database in the world. Mercury samples are collected on gold sand traps and glass fiber filters, respectively.

Semi-volatile monitoring for polynuclear aromatic hydrocarbons (PAHs), Polychlorinated Biphenyls (PCBs), and Dioxans/Furans occurred in 1995 and 1996. Additionally, the USEPA has been monitoring dioxins/furans at Bennington in southwestern Vermont since 1999 and the APCD Technical Services Section has been operating this site since 5/2001.

Currently four air toxic monitoring sites are in operation in Vermont. They are located in Brattleboro, Rutland, Burlington and Underhill.

• Monitoring performed in Brattleboro is source-oriented, as the focus of the monitoring is on exhaust from heavy diesel truck traffic in the area.
  
  
• Rutland represents an urban location with high population exposures while the Underhill site provides background data from a rural location on the western slope of Mt. Mansfield.
  
  
• The Burlington monitoring site was closed in mid-June 2000 due to the construction of a supermarket on the site. The APCD recommenced monitoring in Burlington on January 27, 2003 in the public parking lot on the corner of South Winooski and Main Street.
  
  
• 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.

Monitoring Sites Summary Table
(1993 to 2002)

For further information about air toxics monitoring in Vermont, please see the February, 1998 "Toxicological Advisory Committee AIR TOXICS REPORT" at the following website.

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Last Updated: 1/22/03