NYC-WTC_000199636

NYC 9/11 Public Portal Document

increased over those resulting from background exposure. These estimated cancer risks do not exceed one-in-ten thousand (10^), above which actions are usually taken to reduce exposure.

The average levels of chloromethane and styrene also exceed background and their air comparison values based on cancer effects and long-term exposure. Again, based on the low potential for long-term exposure to elevated levels, this is not expected to result in an appreciable increased cancer risk, but one similar to the risks resulting from exposure to background levels.

Limitations of Health Assessment

The primary limitation of this assessment is that the list of VOCs measured may not be completely representative of the emissions from the fires and recovery activities at the World Trade Center site. The available analytical methods cannot include all of the numerous combustion products that can be generated from the fires, which, in addition to the measured VOCs, could affect air quality and public health. Some chemicals that are known to be produced by fires (e.g. aldehydes, acrolein) and are strong respiratory irritants were not measured.

When odors are present, it is not unusual for some people to experience short-term effects such as respiratory irritation and effects such as headaches and dizziness. These effects tend to diminish once exposure to the odors is stopped, and usually do not result in long-term health consequences. Some people are more likely to experience these effects than others.

Conclusion

The results of the monitoring suggest that the levels of some VOCs in the plume at the debris pile are significantly elevated above typical background levels, and workers at the site should take precautions to limit their exposure. For the VOCs that were measured, the air concentrations outside the work area are not a significant health concern. However, the elevation above background levels of some VOCs indicates that combustion products may be contributing to symptoms of eye, nose and throat irritation that have been reported in workers and residents in the WTC neighborhood. Based on the current r.esults and the expected mitigation of VOC emissions from the site in the future by controlling the fires, continued monitoring for the VOCs sampled is not necessary at this time. It may be useful to assess VOC concentrations again once the fires are controlled to ensure that other recovery activities are not a continuing source of VOCs in the community.

References

Peter S.J. Lees. 1995. Combustion products and other firefighter exposures:^A state of the art review. Occup. Med. 10:691-706.

KOCResults09-28.doc Oct 5, 2001

CITY_21MC100_004067146

NYC-WTC_000199637