In December 2020, under an agreement with U.S. EPA, Arbor Hills installed an H2S monitor at the Ridge Wood Elementary School. This monitor is being operated and maintained by an independent third-party in accordance with an agreement with the U.S. EPA and an access agreement with Northville Public Schools.
H2S is an odorous compound that occurs in natural and industrial settings as a byproduct of biological activity. Arbor Hills monitors H2S near the school to confirm that concentrations are in a safe range, and to provide an early warning signal if potentially unsafe conditions are present, regardless of the source of H2S.
H2S exists in the ambient environment as a colorless gas known for its pungent odor at low concentrations (OSHA; https://www.osha.gov/hydrogen-sulfide). H2S is known by the monikers rotten eggs, sewer gas, swamp gas, stink damp, and sour damp. It occurs naturally in wetlands, shallow ponds, sewers, manure pits, well water, and volcanoes. H2S can also form in hot water heaters. Industrial operations can produce H2S, including oil and gas refining, mining, tanneries, pulp and paper processing, and polymer manufacturing. Landfills produce H2S as a natural byproduct of organic waste decomposition.
The National Research Council (2010) indicates that the H2S concentration in ambient air ranges from about 0.7 to 66 parts per billion (ppb). Background concentrations measured in the communities near Arbor Hills Landfill typically are less than 10 ppb (Benson et al. 2020). These concentrations reflect H2S from all sources in the area, including the landfill. Concentrations in these ranges do not impose a health risk.
The National Research Council, USEPA, Agency for Toxic Substances and Disease Registry (ATSDR), Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH), Michigan Department of Environment, Great Lakes, and Energy (EGLE), and the California Office of Environment and Human Health Assessment (OEHHA) have made recommendations regarding the safety of H2S at different concentrations in ambient air. A summary of these recommendations is in Table 1. Although the odor associated with H2S can be unpleasant even at low concentrations, exposure at low concentrations is not considered to present a health risk (see Table 1). Exposure to very high concentrations or long-term exposure to modest concentrations presents greater risks (see Table 1).
The monitoring system installed at Ridge Wood Elementary School provides alerts if the H2S concentration exceeds a minimum concentration considered safe. Specifically, if the average H2S concentration over a 24-hour time period exceeds 72 ppb, the school administration will be notified that the concentration is elevated but poses no immediate danger. If the H2S concentration exceeds 750 ppb (averaged for a 15-minute time period), school administrators will be notified immediately that the H2S concentration is elevated and precautions should be taken.
Barr Engineering Co. (Barr), an independent environmental consulting company, is operating and maintaining the continuous monitoring system at the school for the Arbor Hills Landfill. Barr is responsible for operating the equipment, collecting the data via remote access, and verifying the accuracy of the data. Barr posts monthly data reports on this website after data verification and quality assurance/quality control review is complete, typically within 15 to 20 days after the end of the previous month. The most recent data can be found here. Past reports can be found here.
Websites where supplemental information on hydrogen sulfide can be found are listed below.
U.S. Environmental Protection Agency
Agency for Toxic Substances and Disease Registry (ATSDR)
Michigan Department of Environment, Great Lakes, and Energy
Citations noted on this website are listed below.
ATSDR (2006). Hydrogen Sulfide, CAS # 7783-06-4. ToxFAQs. Agency for Toxic Substances and Disease Registry, Division of Toxicology and Environmental Medicine ToxFAQsTM, U.S. Department of Health and Human Services, Public Health Service. July 2006. 2 pp.
ATSDR (2016). Toxicological Profile for Hydrogen Sulfide and Carbonyl Sulfide. Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services, Public Health Service. Section 2.3 and Appendix A, Minimum Risk Level. November 2016, 298 pp.
Benson, C., Benson, A, and Hiscott, H. (2020), Olfactory, Physical, and Social Factors Contributing to Odor Complaints at Arbor Hills Landfill, Report to Arbor Hills Landfill by School of Engineering, University of Virginia, 11 December 2020.
California EPA, OEHHA (2000). Hydrogen Sulfide: Evaluation of Current California Air Quality Standard with Respect to Protection of Children. California Environmental Protection Agency, Office of Environmental Health Hazard Assessment, Air Toxicology and Epidemiology Section. Prepared for California Air Resources Board. September 1, 2000. 25 pp.
Michigan EGLE (2021). Michigan Air Toxics System, Initial Threshold Screening Level/Initial Risk Screening Level (ITSL/IRSL). Toxics Screening Level Query Results. Download of Query Results and Notes from: https://www.egle.state.mi.us/itslirsl/results. 6 pp
National Research Council (2010). Acute Exposure Guideline Levels for Selected Airborne Chemicals. Volume 9. Chapter 4. Hydrogen Sulfide. Washington, DC: The National Academies Press. .
NIOSH (2007), NIOSH Pocket Guide to Chemical Hazards, Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute of Occupational Safety and Health. DHHS (NIOSH) Publication No. 2005-149, p. 170.
OSHA (2021). Hydrogen Sulfide, Safety and Health Topics. Occupational Safety and Health Administration, U.S. Department of Labor. https://www.osha.gov/hydrogen-sulfide
USEPA (2003) Toxicological Review of Hydrogen Sulfide. EPA/635/R-03/005, US Environmental Protection Agency, Washington, DC. 74 pp.
American Conference of Governmental Industrial Hygienists (ACGIH) (2020). Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. American Conference of Governmental Industrial Hygienists, Cincinnati, OH. https://www.acgih.org/publications/publication-categories/signature-publications
|Type of Occurrence or Effect||Concentration (parts per million)||Concentration (parts per billion)||Reference|
|Awareness to the presence of H2S
|~0.008 to 0.13||8 to 130||National Research Council. 2010|
|Odor detection threshold
|~0.008||8||California OEHHA. 2000. Hydrogen Sulfide: Evaluation of current California Air Quality Standard with Respect to Protection of Children. 25 pp.|
|Odor detection||0.003 to 0.02||3 to 20||USEPA. 2003. Toxicological review of Hydrogen Sulfide. EPA/635/R-03/005. 74 pp.|
|Average ambient air concentrations||0.0007 to 0.066||0.7 to 66||National Research Council. 2010|
|No appreciable risk of adverse effects
|0.070||70||ATSDR. 1999. Toxicological Profile for Hydrogen Sulfide. Minimum Risk Level. 229 pp.|
|No observable effects
|0.072||72||Michigan EGLE. Initial Threshold Screening Level (ITSL). Toxics Screening Level Query Results.|
(8-hour exposure; AEGL-1)
|0.330||330||National Research Council. 2010|
(10-minute exposure; AEGL-1)
|0.750||750||National Research Council. 2010|
|No irritation of eyes or respiratory tract
(8-hour time-weighted exposure)
|1.0||1,000||American Conference of Governmental Industrial Hygienists (ACGIH). Threshold Limit Value (TLV)|
|Headache, dizziness (30-minute exposure)
||2||2,000||Alberta Health and Wellness. 2002. Health Effects Associated with Short-Term Exposure To Low Levels of Hydrogen Sulphide (H2S) - A Technical Review. October 2002. 86 pp.|
|No adverse effects to workers
(8-hour time-weighted exposure)
|10||10,000||OSHA; Worker Exposure Limit. 29 CFR 1926.55 Appendix A (https://www.osha.gov/hydrogen-sulfide/standards)|
|Immediately dangerous to life or health
(convulsions, respiratory failure)
|100||100,000||NIOSH. 2007. NIOSH Pocket Guide to Chemical Hazards. Publication No. 2005-149. P. 170.|
|Immediately dangerous to life
(loss of consciousness, possible death)
|>500||>500,000||ATSDR. Hydrogen Sulfide (update). July 2006.|
|Type of Occurrence or Effect||Concentration
(parts per billion)
|Notes and Sources|
|Odor detection threshold by sensitive individuals||3 - 20||California EPA, OEHHA. 2000. Hydrogen Sulfide: Evaluation of current California Air Quality Standard with Respect to Protection of Children.
USEPA. 2003. Toxicological review of Hydrogen Sulfide. EPA/635/R-03/005.
|Awareness of odor by general population||8 to 130||National Research Council. 2010.|
|No appreciable risk for 24-hour exposure||70-72||ATSDR. 2016. Toxicological Profile for Hydrogen Sulfide and Carbonyl Sulfide. Minimum Risk Level.
Michigan EGLE. 2021. Initial Threshold Screening Level (ITSL), Toxics Screening Level Query Results. See Note 1 below.
|Headache||330 - 750||8-hr exposure @ 330 ppb, 10-min exposure @ 750 ppb. AEGL-1 exposure. See Note 2 below.National Research Council. 2010.|
|Irritation of eyes or respiratory tract||> 1000||8-hour time-weighted exposure; American Conference of Governmental Industrial Hygienists (ACGIH). 2020. Threshold Limit Value (TLV)|
|Headache, dizziness||> 2000||30-minute exposure, Alberta Health and Wellness. 2002. Health Effects Associated with Short-Term Exposure to Low Levels of Hydrogen Sulfide (H2S) - A Technical Review.|
|Immediately dangerous to life or health. Convulsions, respiratory failure.||100,000||NIOSH. 2007. NIOSH Pocket Guide to Chemical Hazards. Publication No. 2005-149.|
|Immediately dangerous to life. Loss of consciousness, possible death.||>500,000||ATSDR. 2006. Hydrogen Sulfide (update).|
The State of Michigan does not have an air quality standard for H2S, but does have an Initial Threshold Screening Level (ITSL) (i.e., guideline value) of 100 micrograms per cubic meter (µg/m3) for a 24-hour averaging time. The 24-hour (averaging time) ITSL of 100 µg/m3 converts to 72 parts per billion (ppb). The ITSL is an air concentration developed by the Michigan EGLE - Air Quality Division that is without appreciable health risks. For more information, see https://www.egle.state.mi.us/itslirsl/results.asp?Chemical_Name=&CASNumber=&cmdShowAll=&cmdSubmit=&OrderBy=Chemical_Name&page=23)
 National Research Council, 2010. Acute Exposure Guideline Levels for Selected Airborne Chemicals. Volume 9. Chapter 4. Hydrogen Sulfide. Acute Exposure Guideline Levels (AEGLs) represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 hours. AEGL-1 is the airborne concentration above which the general population could experience notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure.