--- title: "Oil, Gas & Petrochemical Site Monitoring | Aethair" description: "Monitoring for upstream, midstream, and refining operations: fence-line VOC and speciated BTEX (benzene), hydrogen sulfide around sour-gas facilities,…" url: https://aethair.io/solutions/oil-gas/ --- Aethair solutions # Oil & Gas / Petrochemical Fence-line VOC, H₂S, and methane leak detection Monitoring for upstream, midstream, and refining operations: fence-line VOC and speciated BTEX (benzene), hydrogen sulfide around sour-gas facilities, methane leak detection, and combustible-gas (LEL) safety, typically paired with wind data for plume direction. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Build a Configuration](https://aethair.io/build/?params=voc,h2s,ch4,wind_speed,wind_direction\&solution=oil-gas) At a glance 4 core parameters [VOC (Total)](https://aethair.io/parameters/voc/) [Hydrogen Sulfide (H₂S)](https://aethair.io/parameters/h2s/) [Methane (CH₄)](https://aethair.io/parameters/ch4/) [Combustible (LEL)](https://aethair.io/parameters/lel/) 3 devices cover it - **Aethair PRO** Aethair MultiGas+ · Aethair H₂S - **Thiamis** R.M. Young Weather Stations 6 standards set limits - [OSHA OSHA Permissible Exposure Limits (PEL)](https://aethair.io/resources/osha-air-quality-standards-compliance/) - [ACGIH ACGIH Threshold Limit Values (TLV)](https://aethair.io/standards/acgih_tlv/) - [EPA EPA Petroleum Refinery Sector Rule: fenceline benzene (40 CFR 63.658)](https://aethair.io/standards/epa_refinery_fenceline/) - [EPA EPA Hazardous Organic NESHAP (HON): fenceline monitoring (40 CFR 63.184)](https://aethair.io/standards/epa_hon_fenceline/) - [AQMD SCAQMD Rule 1180: refinery fenceline and community air monitoring](https://aethair.io/standards/scaqmd_1180/) - [OSHA OSHA Benzene Standard (29 CFR 1910.1028)](https://aethair.io/standards/osha_benzene/) Why it matters ## Why Oil, Gas, and Petrochemical Sites Monitor Air Refineries, gas plants, tank farms, and petrochemical works handle volatile, flammable, and toxic substances at scale, and the same emissions that threaten worker safety also draw regulatory and community scrutiny at the fence line. Leaks of hydrocarbon vapor represent lost product, an explosion risk, and a health hazard, while sour operations release hydrogen sulfide that is dangerous at low concentrations. Fence-line and process-area monitoring exists to protect people on site, to give early warning of a release before it becomes an incident, and to demonstrate to regulators and neighbors that emissions are being controlled. Methane is a growing focus in its own right (as a safety hazard, a lost commodity, and a potent greenhouse gas), and operators are increasingly expected to find and fix leaks quickly across sprawling facilities. What to measure ## What to Measure and the Limits That Apply The core panel covers the main program. Other parameters are added for a specific site or requirement. Every limit below is the published value from the standard that sets it. At the fence line, **total VOCs** capture the overall hydrocarbon burden, while **benzene and the wider BTEX group** are the specific carcinogenic components that draw the tightest scrutiny. **Hydrogen sulfide (H₂S)** is the priority around sour gas and crude because it is acutely toxic at low levels. **Methane (CH₄)** is tracked for leak detection, and **combustible-gas (LEL)** measurement guards against a flammable atmosphere building toward its lower explosive limit. **Wind speed and direction** are indispensable throughout: plume direction determines whether a reading points back to a source on site and where a release is heading. Sites may add **SO₂, NO₂, and CO** from combustion and flaring. VOC (Total) Gases & VOCs [**730 ppb** *1-hour, information-based threshold* · SCAQMD 1180](https://aethair.io/standards/scaqmd_1180/ "total VOCs as non-methane hydrocarbons") Fugitive VOC emissions are the signature air-quality concern of oil and gas operations, from wellheads and tank batteries to refineries, and they include hazardous species such as benzene. Fence-line VOC monitoring, typically with photoionization detectors and wind data, detects leaks and process releases, quantifies community exposure, and provides the evidence behind leak-detection-and-repair and regulatory programs. - **SCAQMD 1180** 730 ppb: total VOCs as non-methane hydrocarbons [VOC (Total): sensors, units, and every standard](https://aethair.io/parameters/voc/) Hydrogen Sulfide (H₂S) Gases & VOCs [**1 ppm** *8-hour TWA* · ACGIH TLV](https://aethair.io/standards/acgih_tlv/) [**30 ppb** *1-hour, notification threshold* · SCAQMD 1180](https://aethair.io/standards/scaqmd_1180/) [**20 ppm** *Ceiling* · OSHA PEL](https://aethair.io/resources/osha-air-quality-standards-compliance/) [**5 ppm** *STEL* · ACGIH TLV](https://aethair.io/standards/acgih_tlv/) Hydrogen sulfide is the defining acute hazard of sour oil and gas operations, toxic at low concentrations and treacherous because it quickly deadens the sense of smell. Continuous H₂S monitoring around wellheads, separators, tanks, and sour-gas facilities (in the breathing zone and at the fence line with wind data) is a primary life-safety control and a standard element of upstream and midstream gas safety. [Hydrogen Sulfide (H₂S): sensors, units, and every standard](https://aethair.io/parameters/h2s/) Methane (CH₄) Gases & VOCs Methane is both the principal product and the principal fugitive-emission problem of oil and gas operations, leaking from wells, valves, compressors, and tanks across the supply chain. Continuous methane monitoring at the fence line and around equipment, with wind data, underpins leak detection and repair, safety against explosive build-up, and the emissions reporting that increasingly shapes the sector. [Methane (CH₄): sensors, units, and every standard](https://aethair.io/parameters/ch4/) Combustible (LEL) Gases & VOCs Flammable hydrocarbon vapors make combustible-gas monitoring essential across oil and gas operations, where a leak building toward the lower explosive limit turns a routine area into an explosion risk. Measuring % LEL around wellheads, tanks, separators, and process equipment, with alarms at a small fraction of the limit, forces ventilation and work stoppage long before any atmosphere can ignite. [Combustible (LEL): sensors, units, and every standard](https://aethair.io/parameters/lel/) BTEX / speciated VOC Often added · Gases & VOCs [**9 µg/m³** *Annual average Δc, fenceline* · Refinery Sector Rule](https://aethair.io/standards/epa_refinery_fenceline/ "benzene; Δc is the highest minus the lowest 14-day fenceline sample, averaged over 26 periods; above it, root cause analysis and corrective action") [**9 µg/m³** *Annual average Δc, fenceline* · EPA HON](https://aethair.io/standards/epa_hon_fenceline/ "benzene; the rule also sets 1,3-butadiene 3, vinyl chloride 3, ethylene dichloride 4, chloroprene 0.8, and ethylene oxide 0.2 µg/m³") [**1 ppm** *8-hour TWA (PEL)* · OSHA benzene](https://aethair.io/standards/osha_benzene/ "benzene") [**8 ppb** *1-hour, notification threshold* · SCAQMD 1180](https://aethair.io/standards/scaqmd_1180/ "benzene; toluene 1,300 ppb and xylenes 5,000 ppb") [**5 ppm** *STEL* · OSHA benzene](https://aethair.io/standards/osha_benzene/ "benzene, 15-minute") [**0.5 ppm** *Action level* · OSHA benzene](https://aethair.io/standards/osha_benzene/ "benzene, 8-hour TWA") Speciated volatile organics (benzene, toluene, ethylbenzene, xylenes, and chlorinated VOCs) from gas chromatography. - **Refinery Sector Rule** 9 µg/m³: benzene; Δc is the highest minus the lowest 14-day fenceline sample, averaged over 26 periods; above it, root cause analysis and corrective action - **EPA HON** 9 µg/m³: benzene; the rule also sets 1,3-butadiene 3, vinyl chloride 3, ethylene dichloride 4, chloroprene 0.8, and ethylene oxide 0.2 µg/m³ - **OSHA benzene** 1 ppm: benzene - **SCAQMD 1180** 8 ppb: benzene; toluene 1,300 ppb and xylenes 5,000 ppb - **OSHA benzene** 5 ppm: benzene, 15-minute - **OSHA benzene** 0.5 ppm: benzene, 8-hour TWA [BTEX / speciated VOC: sensors, units, and every standard](https://aethair.io/parameters/btex/) Sulfur Dioxide (SO₂) Often added · Gases & VOCs [**5 ppm** *8-hour TWA* · OSHA PEL](https://aethair.io/resources/osha-air-quality-standards-compliance/) [**75 ppb** *1-hour, notification threshold* · SCAQMD 1180](https://aethair.io/standards/scaqmd_1180/) [**0.25 ppm** *STEL* · ACGIH TLV](https://aethair.io/standards/acgih_tlv/) Sulfur dioxide: a criteria pollutant from fossil-fuel combustion that irritates the respiratory system. [Sulfur Dioxide (SO₂): sensors, units, and every standard](https://aethair.io/parameters/so2/) Nitrogen Dioxide (NO₂) Often added · Gases & VOCs [**0.2 ppm** *8-hour TWA* · ACGIH TLV](https://aethair.io/standards/acgih_tlv/) [**5 ppm** *Ceiling* · OSHA PEL](https://aethair.io/resources/osha-air-quality-standards-compliance/) Nitrogen dioxide: a criteria pollutant, respiratory irritant, and marker of traffic combustion. [Nitrogen Dioxide (NO₂): sensors, units, and every standard](https://aethair.io/parameters/no2/) Carbon Monoxide (CO) Often added · Gases & VOCs [**50 ppm** *8-hour TWA* · OSHA PEL](https://aethair.io/resources/osha-air-quality-standards-compliance/) [**25 ppm** *8-hour TWA* · ACGIH TLV](https://aethair.io/standards/acgih_tlv/) Carbon monoxide: a toxic, odorless combustion gas that binds to hemoglobin. [Carbon Monoxide (CO): sensors, units, and every standard](https://aethair.io/parameters/co/) Wind Speed Often added · Meteorology Horizontal wind speed. [Wind Speed: sensors, units, and every standard](https://aethair.io/parameters/wind_speed/) Wind Direction Often added · Meteorology Horizontal wind direction (0–360°). [Wind Direction: sensors, units, and every standard](https://aethair.io/parameters/wind_direction/) Hydrogen Fluoride (HF) Often added · Gases & VOCs [**3 ppm** *8-hour TWA* · OSHA PEL](https://aethair.io/resources/osha-air-quality-standards-compliance/ "Table Z-2") [**289 ppb** *1-hour, notification threshold* · SCAQMD 1180](https://aethair.io/standards/scaqmd_1180/) Hydrogen fluoride (HF), a highly toxic and corrosive gas from aluminum smelting, glass etching, and refining. - **OSHA PEL** 3 ppm: Table Z-2 [Hydrogen Fluoride (HF): sensors, units, and every standard](https://aethair.io/parameters/hf/) **Methods and guidance:** [BAAQMD Regulation 12, Rule 15: petroleum refining emissions tracking](https://aethair.io/standards/baaqmd_12_15/) [EPA Method 325A/B: passive sorbent-tube sampling of fenceline VOCs](https://aethair.io/standards/epa_method_325/) [EPA Method 327: canister sampling of ethylene oxide and vinyl chloride](https://aethair.io/standards/epa_method_327/) ![Aethair PRO gas sensor cartridges, each labelled with its gas and color band.](https://aethair.io/images/products/pro/aethair-pro-gas-sensors.webp) The setup ## How a Monitoring Setup Works An Aethair PRO carries gas sensor cartridges for VOCs, H₂S, methane, and combustion gases. It works as a fence-line node for the common hazards, logging continuously and alerting when a concentration rises. Its VOC and methane reading comes from a metal-oxide (MOS) cartridge. This is a sensitive but non-selective indicator that something has changed, rather than a PID or speciated measurement, so any rise it flags is confirmed with a PID or a benzene analyzer. Neither Aethair PRO nor Thiamis lists a hazardous-location rating on its spec sheet, so both go at the fence line and in unclassified areas; inside a classified zone, use certified fixed detection. Speciated benzene and BTEX, or a certified lower-explosive-limit combustible-gas detector, are specialist measurements: a Thiamis gateway connects those professional analyzers and brings their data into the same dashboards and alarms. A weather station on the Thiamis supplies the wind speed and direction that make every gas reading interpretable for plume tracking and source attribution. Nodes are placed around the perimeter and near likely release points, concentrated on the downwind boundary toward the nearest receptors. The recommended configuration below combines a multi-gas node with wind. Use the configurator to add benzene, LEL, or other gases for your site. [Customize this configuration](https://aethair.io/build/?params=voc,h2s,ch4,wind_speed,wind_direction\&solution=oil-gas) Which monitor ## The Monitors in This Configuration The configuration above is built from these monitors. Every reading lands in the same Environet account, with the same alerts and reports. ### [Aethair PRO](https://aethair.io/products/pro/) [Industrial monitor for indoor and outdoor sites. Built-in sensors cover the essentials, and hot-swappable gas sensor cartridges and a differential-pressure option add more.](https://aethair.io/products/pro/) [19 swappable cartridges (H₂S, SO₂, NO₂, CO, O₃, CH₄ and more) in 2 gas sockets, 1 MultiSense socket, and 1 expansion socket](https://aethair.io/products/pro/) [See Aethair PRO](https://aethair.io/products/pro/) ### [Thiamis](https://aethair.io/products/thiamis/) [A gateway that connects the third-party instruments you choose to the Aethair Platform.](https://aethair.io/products/thiamis/) [RS-232, RS-485, SDI-12, and USB · 224 device models from 35 integrations](https://aethair.io/products/thiamis/) [See Thiamis](https://aethair.io/products/thiamis/) What you get ## Readings, Alerts, and the Report That Proves It Every reading goes to the Aethair platform. Here is what a monitoring program gets from it. ### [Live data and alerts](https://aethair.io/platform/environet/) Every reading in Environet as it happens, with alerts by email, SMS, or webhook at the thresholds you set. ### [Compliance reports](https://aethair.io/platform/reports/) Scheduled or on-demand reports against the standards above or your own limits, as PDF or a secure link. ### [Dashboards and AI analysis](https://aethair.io/platform/dashboards/) Live displays for a site or the public, and Noesis answering questions about the data in plain language. ### [Your data, through the API](https://docs.environet.io/) Live and historical readings as JSON or CSV through the Environet API (OpenAPI 3.2), for a building management system, an ERP, or your own applications. The data is yours. [See a sample report](https://aethair.io/docs/aethair-hq-first-floor-report-example.pdf) Article Library ## Reading for Oil & Gas / Petrochemical ### [OSHA Air Quality Standards 2026: PELs & 29 CFR 1910.1000](https://aethair.io/resources/osha-air-quality-standards-compliance/) OSHA air quality standards for indoor and outdoor work: permissible exposure limits, Table Z-1, 29 CFR 1910.1000, and the heat and wildfire smoke triggers. ### [Industrial Perimeter Air Quality Monitoring: Action Levels](https://aethair.io/resources/perimeter-air-quality-monitoring-guide/) What industrial perimeter monitoring requires at fenceline and construction sites: DER-10 CAMP action levels, EPA fenceline rules, and continuous records. ### [Fenceline Air Quality Monitoring: Equipment and Approaches](https://aethair.io/resources/fenceline-air-quality-monitoring/) Compare fenceline air quality monitoring approaches: standalone stations, pelican-case kits, and connected 4G sensor networks. [All articles](https://aethair.io/resources/) Related solutions ## Related Solutions ### [Occupational Safety & Industrial Hygiene](https://aethair.io/solutions/occupational-safety/) Worker exposure, confined space, and heat stress ### [Landfill, Biogas & Odor](https://aethair.io/solutions/landfill-biogas/) Methane, H₂S, and odor complaint response ### [Cabin Air Quality](https://aethair.io/solutions/cabin-air/) Respirable dust, gases, and blast monitoring [All solutions](https://aethair.io/solutions/) Questions ## Oil & Gas / Petrochemical FAQ Why monitor benzene separately from total VOCs? Total VOCs give a useful overall measure of hydrocarbon vapor, but benzene is a specific carcinogen regulated far more tightly than the mixture as a whole. Quantifying it needs a speciated measurement that a general VOC reading cannot provide, which is why fence-line programs single out benzene and the wider BTEX group. What makes wind data essential on an oil and gas site? Wind speed and direction determine whether a gas reading can be traced back to a source on the site and predict where a plume will travel. A concentration spike coinciding with wind from a process unit points to an on-site release; without wind, a fence-line reading is difficult to attribute or act on. What is the difference between LEL and gas concentration monitoring? Concentration monitoring tracks a specific gas for health or emissions purposes, often at low levels. Lower-explosive-limit (LEL) monitoring instead measures how close a combustible atmosphere is to the point where it could ignite, a safety function. The two are complementary, and flammable environments need both. What limits apply at a refinery fence line? US petroleum refineries run fence-line benzene monitoring under 40 CFR 63.658: passive samplers around the boundary, with a corrective-action level of 9 µg/m³ for the annual rolling average of the difference between the highest and lowest reading. The worker limits on this page (OSHA PEL, ACGIH TLV) apply in the breathing zone, not at the fence. The Aethair PRO and Thiamis spec sheets list CE and FCC and no hazardous-location rating, so place them outside classified areas, at the fence line and site boundary. What is the best monitoring setup for oil and gas? An Aethair PRO multi-gas node covering VOCs, H₂S, methane, and combustion gases, paired with a Thiamis-connected weather station for plume direction, and Thiamis-connected benzene/BTEX and LEL instruments where those hazards apply. Site nodes around the perimeter and process areas, and use the configurator to build the configuration.