Volatile Organic Compounds - Benchmarks, Standards and Guidelines Established to Protect Public Health

The following is a description of some the benchmarks, standards and guidelines EPA used to evaluate environmental conditions in the aftermath of the World Trade Center disaster.

Many volatile organic compounds, or VOCs, are found in emissions from burning coal, oil and gasoline and in evaporation at gasoline service stations. These and other sources, such as solvents, cleaners and paints, all contribute to the baseline level of different VOCs found in outdoor air. Some VOCs are also released from tobacco smoke. VOCs are of special concern because they photo-chemically react (in sunlight) to cause ozone or smog. VOC levels in urban areas like New York City fluctuate widely; large differences occur because of both location (near idling cars or trucks vs. on the waterfront) and time (rush hour vs. middle of the night).

Measurements of VOCs from World Trade Center smoke and associated cleanup activities (vehicles and equipment) included background levels from other baseline sources such as city traffic.

To protect workers at the site, EPA attempted to identify the highest concentration levels of VOCs by taking samples lasting for a few minutes. Some of these "grab samples," taken where smoke plumes were seen at the work site, have shown concentrations up to 4000 times higher than those taken in the surrounding streets. EPA and others provided workers with respirators and other protective gear. Used properly, respirators can protect workers from exposure to VOCs and other contaminants at the levels we found. EPA urged workers to use all available protective gear.

VOCs dissipate quickly; grab samples outside the work zone showed dramatically lower levels away from the work zone. Full-day air samples were also taken for many VOCs at eight sites, mainly along the outer edge of the work zone. These measurements confirm the rapid dissipation of VOCs away from the debris pile and illustrate that over a full day, average VOC levels are much lower than those found in the short-duration grab samples. These full-day air samples for all VOCs are below our corresponding screening levels, which were set to protect against significantly increased risks of cancer and other long term health problems, and are based on continuous exposure for a year.

Of the volatile organic compounds we monitored, EPA analyzed benzene first because we thought it had the greatest potential to be present at levels above our screening level. Full benzene information is available on separate web pages.

As described below, we have also analyzed other VOCs.

Results as of mid-April, 2002:

EPA detected 51 VOCs. About half of them are hazardous air pollutants (HAPs), also called toxic air pollutants, under the Clean Air Act. Although we detected these pollutants, their generally low concentrations outside of the work zone mean they pose little risk of long-term health problems from the WTC cleanup effort. A handful of VOCs were not detected in any air samples.

VOCs Detected at Sites Around WTC

EPA has created several programs to reduce VOC emissions from such large urban sources as motor vehicles. More information on these programs can be found at www.epa.gov/otaq.

View Monitoring Data for Volatile Organic Compounds