A national review of hydrogen sulphide exposure, limits and controls in the water industry

Abstract

Australia will adopt revised Workplace Exposure Limits (WEL) for airborne contaminants from the 1st of December 2026 following a 2021 review of over 700 chemicals. Safe Work Australia (SWA) will decide whether to include reduced hydrogen sulphide (H₂S) limits by mid-2025 as part of a Regulatory Impact Assessment for nine chemicals. In 2024, the Water Services Association of Australia (WSAA) gathered its working group comprised of Australian water utilities, regional councils, and Stantec to review the proposed changes and provide input into this decision. This paper details the outcomes of this 2024 review to support an understanding of the levels of exposure within the water industry; the effectiveness and cost of controls; and the adaptations required should the limits change. The resulting recommendation was for a reduction to an alternate H₂S limit which is evidence based, internationally consistent, and practical given compliance with the lower limit proposed by SWA has significant impacts including costs to the Australian water industry estimated at $1.24B.

Introduction

Airborne contaminants that pose a risk with workplace exposure exist within the water sector from chemicals used within water treatment, discharged into the wastewater network, and naturally forming within the wastewater itself. H₂S is the most prevalent airborne contaminant in wastewater systems as it occurs naturally in wastewater under anaerobic (septic) conditions. Workplace H₂S exposure is currently (2025) regulated within Australia to an 8-hour Time Weighted Average (TWA) of 10 parts per million (ppm) and a 15-minute Short Term Exposure Limit (STEL) of 15 ppm. Most international jurisdictions regulate exposure to a relatively lower limit of a TWA of 5 ppm and a STEL of 10 ppm. SWA’s draft revision considered limits of a TWA of 1 ppm and a STEL of 5 ppm based on recommendations by the American Conference of Governmental Industrial Hygienists (ACGIH). 

It is yet to be determined which H₂S values will be adopted for Australia from 2026 and whether an alternative timeline will be considered as the values currently published in 2025 are unchanged pending completion of a regulatory impact assessment as per the timeline in Figure 1. The control of H₂S is common practice within the water industry through a variety of engineering, isolation, administrative, and personal protective methods. However, the impracticality and impacts of applying these controls to the proposed levels was flagged by WSAA in 2021. This paper reports a 2024 study that was undertaken and submitted to provide this input into the ongoing regulatory impact assessment and improve the water industry’s understanding of its current exposure and available controls.

Figure 1: Timeline for Workplace Exposure Limit Review as of March 2025

Toxicology and health effect

Stantec reviewed SWA’s statement of basis for the proposed lower H₂S WELs and their established methodology (SWA, 2018b) to consider their technical approach. An independent review of the toxicological and health effects literature basis for SWA’s proposal to reduce the WELs for H₂S was previously conducted by Stantec in 2021 and updated in 2024. In addition to the key studies referenced by SWA, publicly available reports and studies relevant to exposures in occupational settings were identified. A representative listing was compiled of the exposure limits currently published by other international peer jurisdictions.

Review of the Safe Work Australia Basis

The rationale provided by SWA generally follows the Workplace Exposure Standards methodology outlined in SWA (2018b). In developing their proposed H₂S WELs, SWA relied on four primary sources: the American Council of Governmental Industrial Hygienists (ACGIH 2010), Deutsche Forschungsgemeinschaft (DFG 2013), Scientific Committee on Occupational Exposure Limits of the European Commission (SCOEL 2007) and Dutch Expert Committee on Occupational Safety of the Health Council of the Netherlands (DECOS/HCOTN 2006). The standards listed by the primary sources all post-date the existing SWA standards which were set in 1991, and thus meet the criterion of being more recent than the existing SWA WELs. Since the standards published by the primary sources do not align, SWA methodology suggests using a weight-of-evidence approach and consideration of secondary sources to recommend WELs. SWA adopted the Threshold Limit Values (TLVs) originally derived in 2010 and included in ACGIH (2018) with a technical rationale that has some weaknesses that is explained in this paper. SWA makes the following statement of basis to support their proposal to reduce the WELs for H₂S from the current 8-hour TWA of 10 ppm and STEL of 15 ppm down to an 8-hour TWA of 1 ppm and a STEL of 5 ppm.

“A TWA of 1 ppm (1.4 mg/m3) is recommended to protect for irritation effects and central nervous system (CNS) impairment in exposed workers.”

“A STEL of 5 ppm (7 mg/m3) is recommended to protect for acute irritation effects and CNS impairment in exposed workers.”

SWA also states “The critical effects of exposure are irritation of the eyes and upper respiratory tract and ‘knockdown effect’ at high concentrations”; and “The dose-response curve appears to start at 5 ppm based on evidence in humans and rats (ACGIH 2018).” It would be assumed that a critical effect could also be a “potential negative impact”, which SWA defines as “any adverse health effects that workers might experience due to exposure to hazardous substances or conditions in the workplace. This includes both immediate and long-term health issues such as respiratory problems, skin conditions, and occupational lung diseases.” The Australian Institute of Occupational Hygienists (AIOH, 2021) provided the following comment on SWA’s proposed WES for H₂S- “A TWA of between 1 to 5 ppm and a STEL of between 5 to 10 ppm should be sufficiently protective of health and irritation for the majority of workers.”

SWA indicates that eye irritation (acute irritation) is the critical effect for the proposed STEL of 5 ppm based on ACGIH (2018) statements that effects on the cornea and conjunctiva have been reported at H₂S concentrations ranging from approximately 5 to 50 ppm with serious effects occurring at H₂S levels of 50 ppm or higher with concurrent exposures to other irritants. However, in their TLV Recommendation summary, ACGIH states that “a TLV-TWA of 1 ppm should be sufficient to protect against all unwanted effects of hydrogen sulfide.” No specific health effect or point of departure is referenced, which is where a safe level is determined on a dose-response curve. ACGIH appears to recommend a STEL of 5 ppm “because hydrogen sulfide is extremely malodorous.” Other than odour irritation, no data or studies were referenced by either ACGIH or SWA documenting “potential negative impacts” at H₂S exposure levels below 5 ppm.

The toxicology and health effects studies reviewed by Stantec in 2021 and 2024 do not provide evidence of adverse effects on the CNS, or serious irreversible effects on the eyes or nasal mucosa at exposure levels of 5 ppm or lower; and temporary and reversible sensory responses to odour irritation alone would not meet the SWA criteria for a “potential negative impact” as the basis for setting WELs.

In the occupationally relevant exposure range, there is a paucity of human data to identify a point of departure where odour annoyance transitions to serious non-fatal adverse health effects. However, a weight of evidence evaluation of adverse biological effects plausibly related to H₂S interference with cellular energetics (Goyak & Lewis, 2021) suggests that nasal lesions were associated with H2S exposures of 30 ppm and higher in mice and rats exposed for 90 days (not analogous to exposures in the water industry).

This new information identified by Stantec does not support SWA’s proposal to adopt the ACGIH recommended TWA of 1 ppm, and STEL of 5 ppm based on the low end of the dose-response range for H₂S currently available in the scientific literature. SWA’s reliance on the recommendations of ACGIH (2018) is a questionable basis for the proposed change because ACGIH itself did not provide a technically rigorous explanation for its recommendations, and no evidence is provided that the proposed TWA of 1 ppm and STEL of 5 ppm would be measurably more protective than exposure limits published by a majority of international peer jurisdictions.

Review of International Jurisdictions

The values listed in Table 1 represent the range of H₂S WELs published by international jurisdictions and professional organisations. Twenty of the 28 nations have adopted WELs consistent with the European Union (TWA = 5 ppm; STEL = 10 ppm). Singapore, South Africa, and South Korea have higher WELs (TWA = 10 ppm; STEL = 15 ppm). The People’s Republic of China does not list a TWA value but does list a STEL = 7 ppm. The Netherlands lists a TWA = 1.6 ppm but does not list a STEL value. In the USA, OSHA (enforceable by law) currently lists no TWA value and a Ceiling Limit of 20 ppm. National Institute of Occupational Safety and Health (NIOSH) does not list a recommended TWA, but the Ceiling Limit Value of 10 ppm is consistent with recommendations of the European Union. The 2024 literature review identified evidence to support adoption of a TWA of 5 ppm and STEL of 10 ppm consistent with most jurisdictions, however this did not extend to the ACGIH recommendation for a TWA of 1 ppm and STEL of 5 ppm.

WorkSafe New Zealand (WSNZ) decided in December 2024 to permanently adopt its previously interim limits of a TWA of 5 ppm and a STEL of 10 ppm which are now published in the 15th edition of its Standards (WSNZ, 2025). These interim limits were due to be replaced by the lower ACGIH limits, however stakeholder engagement and re-review of the WEL documentation are attributed to adopting the interim limits as long term limits. These limits are now based on the European Union Scientific Committee on Occupational Exposure Limits (SCOEL) recommendations. 

As of 2025, most representative international jurisdictions have adopted an 8-hour TWA of 5 ppm and a STEL of 10 ppm, consistent with recommendations of the other primary sources and derived from a common toxicology and health effects database. SWA referenced four primary sources (ACGIH, DFG, SCOEL, and HCOTN), but defaulted to the recommendations of ACGIH. The SWA proposal did not include a technical critique of the ACGIH documentation or discussion of information from the other primary sources or secondary data sources, demonstrating that an 8-hour TWA of 1 ppm would be more protective of worker health than Australia’s current TWA of 10 ppm, or more protective than the TWA of 5 ppm currently listed by most international peer jurisdictions. 

Table 1: International Workplace Exposure Limits for Hydrogen Sulphide – Updated September 2024

NV: no value.
IDLH: Immediately Dangerous to Life or Health.
IOELV: Indicative Occupational Exposure Limit Value
a. Source: https://ilv.ifa.dguv.de/substances 
b. ACGIH – 2022 TLVs® and BEIs® - Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati: American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limits for H2S, TWA – 1 ppm; STEL – 5 ppm. The ACGIH recommended WELs were first published in 2010.
c. Canadian Centre for Occupational Health and Safety (CCOHS). 2023. Chemical Profiles – Hydrogen Sulfide. Fact Sheet Last Revised 2023-02-10.
d. ECHA Chemicals Database, Substance Info Card – Hydrogen Sulphide. Last Updated June 7, 2024.
3. The Japan Society for Occupational Health (JSOH). 2022. Recommendation of occupational exposure limits (2022–2023). Environ Occup Health Practice 2022; 4 Occupational Health Practice doi:10.1539/eohp. ROEL2022. May 25, 2022.
f. South Africa. 2021. Department Of Employment and Labour. Regulations For Hazardous Chemical Agents, 2021. Table 3, page 22.

Measurability

To assess the measurability of the proposed limits, it was first necessary to gain an understanding of the levels of H₂S found in the water industry. To this end, Stantec solicited responses from Australian water agencies by means of a survey. Eleven water agencies provided responses in relation to their current understanding of H₂S exposure, with five providing personal exposure monitoring data, the majority of which was recently conducted in response to SWA’s proposed limits. The capabilities of available sampling methods, including real time monitoring using instrumentation and air sample collection, were then assessed to determine whether they could be used to reliably verify compliance with the proposed WEL changes for H₂S at the levels found within the water industry.

Exposure Monitoring Data

Five water agencies provided personal exposure monitoring data gathered from a combination of personal gas monitors (PGM) and air sample collection methods (NIOSH Method 6013) summarised in Table 2. The TWA concentrations of H₂S tend to be relatively low with the highest set 95th percentile (95%ile) at 1.07 ppm. STEL concentrations ranged from 0.0 (not detectable) to 3.36 ppm. Peak values between sets varied from 20.2 to 55 ppm with one extreme peak of 183.9 ppm reported by a PGM.

Table 2: Summary of Exposure Monitoring Results

* Results reported as “0” or “0.0” with no detection threshold specified
95%ile – 95th Percentile calculated
Max – Maximum concentration measured
Min - Minimum concentration measured

An H₂S study conducted by Austigard et al. (Austigard, Smedbold, & Svendsen, 2022) surveyed 59 workers from 2015-2021, totalling 40,000 work hours, across a variety of sewage treatment plants (STP), sewage pumping stations (SPS) and water distribution sites in Norway. Figure 2 reproduced from Austigard’s study shows that a low TWA for H₂S such as 0.001 ppm can have a much higher maximum exposure such as 10 ppm. This finding correlates with data from Australian water agencies, which is depicted in Figure 3, showing both TWA and peak exposure values from Table 2.

Accurate and reliable measurements of H₂S are key considerations in establishing compliance with the proposed TWA, STEL, and IDLH values. Based on the results of exposure monitoring in industry, the selected method(s) of assessment must be capable of measuring variable concentrations, most notably peak values, while also verifying that the exposure levels remain below the TWA.

Figure 2: Maximum H2S level against the TWA level for STPs (Austigard, Smedbold, & Svendsen, 2022)

Figure 3: Maximum H2S level against the TWA level for provided by Australian survey respondents

Real-Time Monitoring

Personal gas monitors (PGMs) serve as the standard method of monitoring H₂S in the water industry. Currently available PGMs used by Australian water agencies include the Ventis MX4 manufactured by Industrial Scientific and the X-am 2500 manufactured by Dräger. The Ventis MX4 has a reported accuracy of 5% across the measurement range (0-500 ppm) (IS, 2020).The X-am 2500 has a reported accuracy of 5% across the measured value but a detection limit of 0.4 ppm (Dräger, 2024). 

The electrochemical sensor technology used by the PGMs allow them to monitor H₂S concentrations in real time, where dangerously elevated levels can be detected immediately. The PGMs are limited, however, in their sensitivity at the low levels that are typically measured in the industry. 

To verify compliance with the proposed TWA of 1 ppm for H₂S, the PGM must be able to measure concentrations as low as 0.5 ppm (50% of the WEL, called the “action level”) or an even more aggressive target of 0.01 ppm (1% of the WEL) in accordance with the exposure management strategy described by the American Industrial Hygiene Association (AIHA, 2015). However, studies have shown that electrochemical sensor technology has limited accuracy below 5 ppm of H₂S (Hemingway, Walsh, Hardwick, & Wilcox, 2012). 

A key feature of PGMs is the alarm function, where alarms provide both audible and visual alerts when H₂S concentrations exceed the preset alarm limit (typically set at the action level). The alarm serves as a practical way to notify workers to exit the work area before the TWA is reached. However, PGMs will tend to alarm frequently when peak values are common in the work environment. Workers risk becoming conditioned to disregard the alarms as a result, effectively eliminating their value and purpose.

Other issues compromise the results on the lower end of the PGM measurement range. Cross-interference may occur with other gases present in the work environment (e.g., chlorine), where the working electrode within the electrochemical sensor is not selective in its response. Equipment drift may also occur, which is a measurement error caused by the gradual shift in measured values over time. When the TWA is particularly low, as is the case for H₂S, the impact of equipment drift is magnified, reducing the reliability of data collected. Extremes of temperature and humidity will also impact the accuracy and performance of the PGM.

Air Sampling Collection

Discrete air samples that are collected in the worker breathing zone and analysed using validated sampling and analytical methods are known to provide highly accurate and reliable results. It is important to note that there is a time lag between sample collection and the receipt of laboratory data, where decisions in real time cannot be made.

Air samples to assess the TWA for H₂S are collected using one of two available methods:
National Institute of Occupational Safety and Health (NIOSH) Method 6013 (NIOSH 6013)
Occupational Safety and Health Administration (OSHA) Method 1008 (OSHA 1008)

NIOSH 6013 specifies a Limit of Detection (LOD) of 11 micrograms (μg) per sample. Based on the maximum air volumes collected over an 8-hour shift (TWA) and 15-minute interval (STEL), the LOD for H₂S concentration is calculated to be 0.2 ppm and 0.35 ppm, respectively. These results are below the action levels for the proposed TWA and STEL of 1 ppm and 5 ppm, respectively. However, NIOSH 6013 further describes a working range of 0.6 to 14 ppm in reliably assessing worker exposure, which at its low end is slightly above the action level for the proposed TWA.

NIOSH 6013 is limited by the positive interference of sulphur dioxide (SO₂) in the environment when sampling for H₂S. This limitation may be mitigated by sampling for SO₂ at the same time to evaluate its presence. Sampling methods for SO₂ may include the use of PGMs or sample collection methodology (e.g., NIOSH 6004). 

Alternatively, OSHA 1008, which uses a modified version of NIOSH 6013 to eliminate the interferences of common compounds such as SO₂, may be selected as the sample collection method. OSHA 1008 specifies a “Reliable Quantitation Limit” of 0.520 ppm for TWA concentrations, which is marginally above the action level for the proposed TWA of 1 ppm. The method also specifies Reliable Quantitation Limits of 0.831 ppm for Ceiling concentrations and 1.25 ppm for Peak concentrations (noting Ceiling standards may be exceeded for specified periods, whilst Peak standards must never be exceeded), noting there is no specific reference to a STEL sampling interval.

Both NIOSH 6013 and OSHA 1008 may be used to assess compliance with the proposed TWA for H2S, however there are additional costs to consider by way of ruling out the presence of SO₂ when using NIOSH 6013.

Measurability Discussion

The results of exposure monitoring conducted by five respondents to our industry survey of Australian water agencies indicate that TWA concentrations of H₂S tend to be relatively low compared to the current and proposed WELs. However, the frequency of elevated peak values found in industry data are of concern, particularly with alarm levels set to or below the TWA, which may lead to workers becoming conditioned to disregard these alarms when they frequently go off. This information demonstrates the need for exposure monitoring methods that are capable of measuring variable concentrations, most notably peak values, while also being able to reliably verify that the exposure levels remain below the TWA. 

PGMs are typically used in industry to measure H₂S in real time, which captures the variability and peaks in concentrations. PGMs are challenged by issues of sensitivity at low concentrations, cross-interferences with other gases, and equipment drift (Hemingway, Walsh, Hardwick, & Wilcox, 2012). TWA concentrations are therefore difficult to accurately and reliably determine using this technology. 

Air sample collection methods (i.e., NIOSH 6013 or OSHA 1008) are capable of providing accurate and reliable TWA results. However, these methods are limited in their accuracy below the action level and inability to discern variable and peak concentrations. There is also a significant time lag between sampling and the receipt of analytical results. 

Given the limitations associated with available exposure monitoring methods, it would be difficult to demonstrate compliance with the proposed TWA limits, particularly in a manner that allow water agencies to action the results in a meaningful way.

Controls and associated cost

Controls and associated costs were developed based on Stantec’s experience in the sector, industry consultation, and a review of the controls considered by SWA in a broader impact assessment (SWA, 2018a). The Australian water industry applies a wide range of controls to mitigate exposure to H₂S as it naturally occurs in sewage and must additionally be controlled to mitigate asset corrosion and odour nuisance. A list of applicable controls was developed, including administrative, protective (Figure 4 left), engineering and isolation (Figure 4 right), and average unit costs were estimated for each control applicable in achieving the proposed WEL. The unit costs were produced using stochastic methods suitable for a Level 5 estimate (-50%/+100%) following the Office of Impact Analysis (OIA) Cost Benefit Analysis Guidance (OIA, 2023) and Regulatory Burden Measurement Framework (OIA, 2024). The application of each control was then determined based on an additional need to comply with the proposed WEL with reference to the available industry data provided within the survey. The methodology is outlined in Figure 4 with examples in Figure 5.

Figure 4: Methodology for Determining Control Unit Costs for Australian Water Industry

Figure 5: A typical Chemical Dosing Unit (Left) and major sewage treatment plant (STP) Odour Control Unit (Right)

Cost Results

Table 3 outlines the resulting control unit costs and unit application determined for the Australian water industry to comply with SWA’s proposed WELs. Controls identified in the review but not adopted in the cost estimate include eliminating sulphur, wastewater aeration/dilution, robotics, and broader confined space classification. It should be noted that the engineering and isolation controls were based only on the marginal additional controls needed to comply with the proposed WELs, and not applied to every STP and SPS. 

Table 3: Control Unit Costs

EP: Equivalent Population, based on servicing 85% of the Australian population of 26M.
STP: Sewage Treatment Plant
SPS: Sewage Pumping Station
Cost methodology detailed in Figure 4.
* Unit Applications are estimated based on: 
Exposure monitoring data and associated studies from Large Regional A which covered the most representative list of employees and infrastructure. 
Low and High-risk thresholds for control application were determined based off the prevalence of current controls.
27,700 Australian Water Industry full time equivalent employees; 82% of which having activities onsite reflected by the exposure monitoring.
720 STPs and 10,549 SPSs in Australia from published industry data and survey responses. 
** Apparent discrepancy in the percentage difference is due to rounded figures and not actual. 

Table 4 presents the annualised costs as a net present value with a discount rate of 7% over the default 10-year period as prescribed in the OIA Cost Benefit Analysis Guidance (OIA, 2023). The upfront (infrastructure) costs have been linearly distributed over the 10-year period. This estimate uses available data for the average utility applying a minimum level of control and is consequently high-level and not comprehensive, as it is for the sole purpose of informing the consultation period. 

Table 4: Annualised Cost Impact of Additional Controls

Control Discussion

The proposed change to H₂S exposure limits is estimated to have a cost impact of over $1.24B over a 10-year period to expand the use of existing monitoring, respiratory protection, and H₂S control infrastructure. A significantly higher estimate was produced based on industry submissions in the order of $6-7B (WSAA, 2022). The lower cost is based on a significant reliance on lower order administrative and protective controls which is not the current practice within the water sector. However, engineering and isolating controls to action levels below the TWA of 1 ppm are not considered practical due to large number of disperse assets. The $1.24B scenario and increased reliance on low order controls is considered a more realistic outcome of the proposed change. Non-cost themes of timeline, labour, measurability and impacts to small councils and large infrastructure programs were additionally raised as part of the survey and consultation.

The peak exposures identified earlier suggest there could be a health benefit in applying additional controls as although brief, exposures above 10 ppm are associated with negative effects beyond odour irrigation. Broader use of PGMs would be recommended for this however, as discussed earlier they could not be relied upon for compliance if the TWA was as low as 1 ppm. Adopting the evidence backed limits of a TWA of 5 ppm and STEL of 10 ppm would allow the use of PGMs to be expanded and at a lower alarm level. Any further infrastructure controls needed to comply would be targeted and consistent with most of the international water sector who already operate under these limits. This is considered an effective way to reduce the health risk that could be posed by these peak exposures.

SWA have considered preliminary costing which was submitted for their October 2024 Consultation Paper (SWA, 2024). The consultation paper references the water industry data provided with an adopted cost of $997M, an overall industry cost at $1,298M, and an overall industry benefit of $7M associated with the H₂S change. The benefit costing is caveated as limited in scope as it is based on a reduction in direct costs associated with worker’s compensation, and states the following:

“No health benefits were quantifiable for hydrogen sulphide. This is because no estimates of the current burden of disease attributable to workplace exposure to hydrogen sulphide were identified through research or stakeholder engagement. However, this does not mean that the introduction of the proposed WEL for hydrogen sulphide would not result in benefits to workers and the community.”

Conclusion

SWA have advised that a decision regarding hydrogen sulphide exposure limits will occur mid-2025, which during consultation were to either retain the current limits or adopt those proposed. The 2024 review did not identify evidence that the lower limits proposed would be more protective than the more commonly adopted TWA of 5 ppm and STEL of 10 ppm. A recommendation was made for a reduction to these limits, instead of the proposed or current limits, on the following basis:

• Consistency with the majority of international jurisdictions (Table 1).
• Addresses the acute irritation affects proposed by SWA, reduces the likelihood of peak exposures, and is considered equally protective of health and irritation by the Australian Institute of Occupational Hygienists (AIOH, 2021).
• Aligns with the evidence from secondary data sources sufficient to make a recommendation with good confidence as per Stage 2 – Part 3 of the SWA Methodology (SWA, 2018b).
• Measurable to a meaningful level using real-time and air sample collection methods (NIOSH).
• Avoids significant impact on the Australian water industry, as current controls with respect to infrastructure, equipment, and practices would follow international jurisdictions with these limits. 

Acknowledgements

We would like to acknowledge the efforts of the survey respondents and the broader water industry for providing access, data, and insight into this topic.

Abbreviations

ACGIH     American Council of Governmental Industrial Hygienists
AIHA       American Industrial Hygiene Association
AIOH       Australian Institute of Occupational Hygienists
CNS         Central Nervous System
DFG         Deutsche Forschungsgemeinschaft
EP            Equivalent Population
HCOTN    Health Council of the Netherlands
H₂S          Hydrogen sulphide
IDLH        Immediately Dangerous to Life or Health
LOD          Limit of Detection
NIOSH     National Institute for Occupational Safety and Health
OIA          Office of Impact Analysis
OSHA       Occupational Safety and Health Administration
PGM         Personal Gas Monitor
ppm         Parts per million
SCOEL    (European Union) Scientific Committee on Occupational Exposure Limits
SO₂          Sulphur Dioxide
SPS          Sewage Pump Station
STEL        Short Term Exposure Limit
STP          Sewage Treatment Plant
SWA         Safe Work Australia
TLV          Threshold Limit Value
TWA         Time Weighted Average
WEL         Workplace Exposure Limit (formerly WES,  Workplace Exposure Standards)
WSAA      Water Services Association of Australia
WSNZ      Work Safe New Zealand

The Authors

Dominic Gibbs
Dominic is a senior engineer in Stantec’s Water Team with 9 years’ experience in the sector. With Stantec Dominic has completed dozens of infrastructure projects across Australia and New Zealand in wastewater and air quality. Dominic also has 5 years’ experience in Utility Wastewater operations and infrastructure planning teams.

Deborah L Gray 
Deborah is a Principal Toxicologist in Stantec’s Columbus, Ohio USA office. She has over 40 years of experience in public health and occupational toxicology and risk assessment.

Pamela Sears 
Pamela is a Senior Industrial Hygienist in Stantec’s Dartmouth, Nova Scotia, Canada office. She has over 30 years of experience in the practice of industrial hygiene. Her work as a consultant has provided a wealth of work opportunities to explore and assess a wide diversity of workplaces.

Dr Ari Shammay 
Ari is Stantec’s Australian and New Zealand Practice Lead for Odour, Septicity and Air Quality. Ari has been working with hazardous gases for over 15 years across Australia, New Zealand, Europe, the Middle East and the United State of America. Ari completed his PhD in foul air mitigation across sewer networks around Australia.

James Goode
James is the Utility Performance Manager at the Water Services Association of Australia. James has over 20 years’ experience in the water industry in both irrigation and urban water. James has worked in various roles throughout his career including design, construction, and asset management in both water and sewage. James’ current role has a focus on facilitating asset management excellence to deliver improved customer service within the water sector. James also had contributed to various areas advocacy work for the sector to ensure the best community outcome. 

References