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  1. The levels of total reduced sulfur (TRS) measured in the community's ambient air along with the indoor and ambient air screening results for hydrogen sulfide (H2S) indicate a threat to public health--especially to those with pre-existing respiratory problems and those located closest to the potential fallout areas of the sources.
  2. The levels of TRS measured in the community's ambient air frequently exceed the NDEQ's 30-minute ambient air quality standard.
  3. The levels of H2S/TRS inside at least 1 residence may exceed the NDEQ 30-minute TRS ambient air quality standard.
  4. Because of the presence of H2S/TRS in both the ambient air and inside residences, opportunities for community members to eliminate or reduce their own exposures are difficult.
  5. Based on calls to the odor hotline and discussions with residents, levels of H2S and other noxious-smelling compounds found in the South Sioux City/Dakota City ambient air are resulting in a diminished quality of life for area residents.
  6. The limited human data on adverse health effects of repeated low dose exposures to hydrogen sulfide and total reduced sulfur indicate that H2S and TRS levels in the ambient air could result in symptoms reported by residents, including headaches, eye irritation, respiratory problems, and nausea.
  7. If sulfur dioxide (SO2), is present at levels above National Ambient Air Quality Standards, an added health threat may exist.
  8. Given the levels of H2S/TRS in the ambient air, it is possible that the workers at thesource(s) of H2S/TRS may be exposed to levels that exceed occupational exposure limits.


  1. Reduce levels of TRS and H2S in the community's ambient air to below levels of health and regulatory concern as soon as possible.
  2. Stop community exposures to TRS and H2S in their indoor air.
  3. Conduct additional ambient air monitoring for SO2 and, if found above ambient air quality standards, reduce levels as soon as possible.
  4. Local, state, and federal health agencies: provide health education for community members and area health care providers on occupational and nonoccupational exposures to TRS, H2S, and SO2.
  5. Local, state, and federal health agencies: consider conducting a health study of the population.
  6. Once the source(s) of TRS and/or H2S are found, local, state, and federal healthagencies: work with the National Institute for Occupational Safety and Health todetermine whether there is a need for a health hazard evaluation of workers.
  Lynn Wilder, CIH
Environmental Health Scientist
Concurrence: Kenneth G. Orloff, Ph.D., DABT
Senior Toxicologist


  1. Title 129, Chapter 4, Nebraska Department of Environmental Quality.

  2. Zellweger Analytics, Inc., MDA Technical Note. Instrument Accuracy and Precision. Tech Note Number 971131 1/93.

  3. NDEQ TRS Report, October 1997.

  4. Toxicological Profile for Hydrogen Sulfide, Draft for Public Comment. ATSDR,September 1997.

  5. Jappinen P, Vilkka V, Marttila O, et al. 1990. Exposure to hydrogen sulphide andrespiratory function. Br J Ind Med 47:824-828.

  6. U.S. Public Health Service: The air pollution situation in Terre Haute Indiana withspecial reference to the hydrogen sulfide incident of May-June 1964. NTIS Report No.PB-227 486.

  7. Bhambhani, Y., Singh, M. 1991. Physiological effects of hydrogen sulfide inhalationduring exercising in healthy men. The American Physiological Society 1872-1877.

  8. Bhambhani, Y., Burnham, R., Snydmiller, G., MacLean, I., Martin, T. 1994.Comparative physiological responses of exercising men and women to 5 ppm hydrogensulfide exposure. American Industrial Hygiene Association Journal (55)1030-1035.

  9. Bhambhani, Y., Burnham, R., Snydmiller, G., MacLean, I., Lovlin, R. 1996. Effects of10 ppm hydrogen sulfide inhalation on pulmonary function in health men and women. Journal of Environmental Medicine. 38(10)1012-1017.

  10. ACGIH. 1991. Documentation of the threshold limit values and biological exposureindices, sixth edition. American Conference of Governmental Industrial Hygienists, Inc.,Cincinnati, OH. 786-788.

  11. Hill FB. 1973. Atmospheric sulfur and its links to the biota. Brookhaven Symp Biol30:159-181.

  12. Bottenheim JW, Strausz OP. 1980. Gas-phase chemistry of clean air at 55 degrees Nlatitude. Environmental Science and Technology 14(6):709-718.

  13. Toxicological Profile for Sulfur Dioxide, Draft for Public Comment, ATSDR, September 1997.

  14. IRIS. 1995. Integrated Risk Information system. U.S. Environmental Protection Agency. Washington, DC. July 3, 1995.

  15. AIHA. 1991. Emergency Response Planning Guidelines: Hydrogen Sulfide. AmericanIndustrial Hygiene Association. Fairfax, VA.

  16. Ellenhorn M, Barceloux D. 1988. Medical Toxicology, Diagnosis and treatment ofhuman poisoning. New York, NY.

  17. CIIT. 1983c. 90 Day vapor inhalation toxicity study of hydrogen sulfide in Sprague-Dawley rats. Report to the Chemical Industry Institute of Toxicology, Research TrianglePark, NC, by ToxiGenics, Inc. CIITdocket #32063.

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