District steam pipe geyser or underground electrical vault manhole explosion: carbon monoxide push and asbestos mud fallout¶

Walking down a dense urban street in New York City, Boston, Philadelphia, San Francisco, Toronto, London, or Paris when a 135-kilogram (300-pound) cast-iron manhole cover suddenly chatters, belches thick yellow-gray acrid smoke, or launches 15 meters (50 feet) into the air on a column of fire, or hearing a deafening jet-engine roar as a high-pressure district steam main (1,000 to 1,400 kPa / 150 to 200 psi at 200 degrees Celsius / 400 degrees Fahrenheit) erupts through the asphalt into a 10-story geyser of scalding mud and rock, is a dual-hazard urban infrastructure emergency. Most pedestrians and apartment residents assume that once they cross the street away from a smoking manhole or steam crater, they are out of danger. In reality, the two deadliest threats from an underground utility blast travel invisibly inside adjacent buildings and across entire city blocks.

First, during an underground electrical cable or transformer vault fire ("Manhole Event"), intense electrical arcing inside oxygen-starved underground conduits thermally decomposes (pyrolyzes) paper-insulated lead-covered (PILC) and synthetic rubber/polyethylene cable jackets into massive volumes of flammable, lethal Carbon Monoxide (CO, often exceeding 10,000 to 50,000 parts per million), Hydrogen (H2), Methane (CH4), and Acetylene (C2H2). When the cast-iron manhole cover stays seated or explodes, underground gas pressure forces this odorless, colorless 10,000+ ppm Carbon Monoxide straight through unsealed basement service-conduit sleeves into adjacent apartments and storefronts, triggering indoor CO alarms and causing rapid unconsciousness even in buildings that still have electricity. Second, during an urban district steam main rupture ("Water Hammer Blast") on legacy pipe networks installed prior to 1980, the supersonic steam jet pulverizes historical Chrysotile and Amosite Asbestos thermal pipe insulation and rains wet gray asbestos-laden mud and slurry across multiple blocks. If you witness a smoking, chattering, or exploding manhole or a roaring steam geyser, evacuate upwind at least 30 to 100 meters (100 to 330 feet) and call your local emergency number (911 in the United States and Canada, 112 across the European Union, 999 in the United Kingdom; see emergency numbers) immediately. For related urban utility emergencies, see district steam pipe explosion, manhole fire, and underground vault blast, stray voltage on metal streetlights, sidewalk manhole covers, and dog-walking shocks, and natural gas odorant mercaptan fade, odorless underground gas migration into basements, and explosive limits.

Do this now¶

1. Clear the street and sidewalk immediately: move at least 30 meters (100 feet) upwind from a smoking/flashing electrical manhole, or 100 meters (330 feet) upwind from an erupting district steam geyser. Never walk over a smoking, humming, or vibrating manhole cover or sidewalk vault grate, and never drive a car over a smoking manhole (the hot vehicle exhaust or catalytic converter can ignite the hydrogen/carbon-monoxide gas plume pouring out of the vent holes, blowing the 135-kg / 300-lb cover straight through the floorboard of your car).
2. If you live or work in a building on the same block as a smoking or exploding electrical manhole, evacuate the basement and ground floor immediately and check for Carbon Monoxide (CO) migration. Underground electrical duct banks connect directly into the basement electrical point-of-entry (POE) walls of every building on the block. Pyrolysis of burning underground cable insulation generates 10,000+ ppm of odorless Carbon Monoxide that migrates into basements without any smell of smoke. If your indoor CO detector sounds, or if anyone in the building feels a sudden throbbing headache, dizziness, or nausea during a street manhole fire, evacuate the entire building into fresh air and tell arriving firefighters: "We have a smoking manhole on the street and suspect underground Carbon Monoxide migration into our basement."
3. If caught near a high-pressure district steam pipe rupture, run upwind out of the falling mud and condensation cloud to prevent 200 C (400 F) inhalation airway scalds. High-pressure municipal steam (175 to 200 degrees Celsius / 350 to 400 degrees Fahrenheit) causes instantaneous full-thickness (third-degree) skin burns and lethal laryngeal edema if superheated vapor is inhaled. Do not shelter inside a lobby directly facing the rupture if the glass windows are being pelted by rocks or boiling slurry; exit through a rear service door or move to an upper floor on the far side of the building and shut off all building HVAC outside-air intakes.
4. Treat all gray mud, dust, and fibrous debris from an urban steam pipe explosion as presumed friable Chrysotile Asbestos until tested by municipal environmental agencies. If wet gray slurry, dust, or white/gray fibrous material from a steam blast lands on your hair, skin, coat, or shoes, do NOT walk into your apartment or car wearing those clothes and never brush dry dust off with your hands. Strip off your outer clothing and shoes outside, seal them inside double plastic trash bags moistened with a mist of water (wet-bagging), and shower thoroughly with lukewarm water and soap, washing your hair first.
5. Avoid all wet pavement, metal sidewalk vault grates, and streetlights near a steaming or smoking manhole (Stray Voltage / Step Potential). Steam condensation and firefighter hose runoff flood underground 120/208-volt secondary networks and 13,800-volt primary feeders, energizing metal sidewalk grates, cast-iron covers, and wet concrete. Walk on dry center asphalt well clear of metal covers, keep dogs lifted off wet sidewalks, and shuffle with both feet together if you feel any tingling in your legs.
6. Never re-enter a building after a manhole fire or steam blast until the Fire Department and Utility Crew verify 0 ppm Carbon Monoxide in the basement AND certify whether the facade/sidewalk is free of asbestos. Even after a manhole fire goes out on the street, pockets of 500 to 2,000 ppm Carbon Monoxide remain trapped inside basement utility rooms, elevator shafts, and wall cavities for hours until firefighters ventilate with positive-pressure fans and plug the underground conduit ducts.

Decision tree: underground manhole fire vs. district steam pipe geyser¶

flowchart TD
    A["Underground street utility emergency in dense urban area"] --> B{"Is it an Electrical Manhole Event OR a High-Pressure Steam Rupture?"}
    B -->|"1. Electrical Manhole: Black/yellow acrid smoke, tar odor, chattering cover, blue/orange sparks"| C["Evacuate 30+ meters (100+ ft) upwind; do NOT drive or walk over any manhole covers"]
    B -->|"2. District Steam Rupture: Deafening white vapor jet, flying asphalt/mud, boiling street water"| D["Run 100+ meters (330+ ft) upwind out of vapor/mud plume; avoid glass windows facing crater"]
    C --> E{"Are you inside a building on the same street block?"}
    E -->|"Yes"| F["Evacuate basement & 1st floor immediately: 10,000+ ppm Carbon Monoxide pushes through cable ducts"]
    E -->|"No: Outdoors"| G["Call 911 Fire Dispatch & Electric Utility; stay off wet metal grates and streetlights"]
    F --> H{"Is the indoor CO alarm sounding OR do occupants feel headache/nausea?"}
    H -->|"Yes"| I["Evacuate entire building to fresh air and alert Fire Dept HazMat for basement CO readings"]
    H -->|"No"| J["Keep basement door closed, open upper windows on clean-air side, wait for FDNY/Fire CO clearance"]
    D --> K{"Did gray mud, dust, or fibrous debris from the steam blast land on you?"}
    K -->|"Yes: Potential Chrysotile Asbestos fallout"| L["Do NOT dry-brush or wear inside: Strip shoes/outerwear outside, wet-bag in double plastic, and shower"]
    K -->|"No"| M["Shut off building HVAC intakes, seal windows with tape, and await DEP/EPA asbestos test results"]

Hazard 1: Underground Electrical Vault Fires, Manhole Explosions, and the Basement Carbon Monoxide Push¶

In cities with dense underground electrical grids (network distribution systems), hundreds of high-amperage secondary mains (120/208 V or 277/480 V carrying 1,000 to 4,000 amps) and high-voltage primary feeders (4,160 V to 34,500 V) run side-by-side through narrow clay, PVC, or steel duct banks 1 to 3 meters (3 to 10 feet) beneath the street.

How a winter road-salt thaw or summer heatwave triggers a manhole blast and indoor CO poisoning¶

+-----------------------------------------------------------------------------+
|   HOW UNDERGROUND CABLE PYROLYSIS PUSHES 10,000+ PPM CO INTO BASEMENTS      |
+-----------------------------------------------------------------------------+
|                                                                             |
|  [STREET SURFACE]        (Cast-Iron Manhole Cover: 60 to 135 kg / 300 lb)   |
|  ===================[=======]=============================================  |
|                     | Vents |                                               |
|   +-----------------+-------+-----------------+                             |
|   |       UNDERGROUND ELECTRICAL VAULT        |                             |
|   |  1. Road salt / heat causes 13.8kV or     |     [APARTMENT BUILDING]    |
|   |     120/208V cable insulation to arc.     |     +-------------------+   |
|   |  2. Anaerobic pyrolysis of XLPE / PILC    |     | 1st Floor Living  |   |
|   |     cable jacket generates:               |     | (CO rises up      |   |
|   |     * Carbon Monoxide (CO: 10,000+ ppm)   |     |  stairwell/pipes) |   |
|   |     * Hydrogen (H2) & Methane (CH4)       |     +-------------------+   |
|   |  3. Vault pressure forces odorless CO     |     | BASEMENT WALL     |   |
|   |     down the conduit duct bank: ================> [Unsealed Conduit |   |
|   |                                           |     |  Service Sleeve]  |   |
|   +-------------------------------------------+     +-------------------+   |
+-----------------------------------------------------------------------------+

1. Why the Lights Stay On inside Your Building While the Cable Burns (Secondary Network Grid):
2. Unlike suburban radial power lines that trip a breaker the instant a wire shorts out, downtown urban secondary network grids tie dozens of underground transformers together in a parallel mesh designed to burn clear a short circuit ("burn-off") so skyscrapers, hospitals, and subways do not lose power. As a result, a faulted 120/208-volt cable bundle inside a street manhole can arc and cook at 1,000 degrees Celsius (1,800 degrees Fahrenheit) for 30 to 90 minutes while your apartment lights remain completely on.
3. Why CO Migrates Into Basements Before You Smell Smoke:
4. As the underground cable jacket decomposes inside the sealed conduit, the sticky black soot and heavy tars condense on the cold walls of the underground pipe, filtering out the visible smoke and burnt-plastic odor while allowing pure, odorless, colorless Carbon Monoxide (CO) gas under high pressure to shoot straight through the conduit sleeve into your building's basement.
5. Fire departments in New York (FDNY), Boston (BFD), and Toronto routinely measure 1,000 to 15,000 ppm of Carbon Monoxide inside the basements of rowhouses and apartment buildings 50 meters (165 feet) down the block from a smoking manhole, well above the 1,200 ppm NIOSH Immediately Dangerous to Life or Health (IDLH) threshold where 3 to 5 breaths cause confusion and collapse.

Hazard 2: High-Pressure District Steam Main Ruptures (Water Hammer) and Asbestos Fallout¶

Dozens of major cities operate underground District Steam Systems (such as Con Edison's 170-kilometer / 105-mile Manhattan steam network, along with district steam grids in Boston, Philadelphia, Baltimore, St. Louis, Denver, Indianapolis, Seattle, Paris [CPCU], and Munich) that pipe superheated steam at 1,000 to 1,400 kPa (150 to 200 psi) and 175 to 205 degrees Celsius (350 to 400 degrees Fahrenheit) beneath the streets to heat skyscrapers, sterilize hospitals, and drive steam-turbine air conditioning chillers.

Why heavy rainstorms trigger violent "Condensation-Induced Water Hammer" explosions¶

1. The Physics of a Steam Main Water Hammer (Condensation Shockwave):
2. High-pressure steam pipes must remain completely dry on the outside and drain internal liquid condensate continuously through steam traps.
3. When a torrential summer thunderstorm, water-main break, or clogged street sewer floods an underground steam manhole with cold rainwater, the cold water submerges the exterior of the 200-degree-Celsius (400-degree-Fahrenheit) steel steam pipe. Inside the pipe, a pocket of superheated steam suddenly cools and collapses back into liquid water (condenses), creating an instantaneous vacuum void inside the pipe.
4. Multi-ton slugs of boiling condensate water inside the main are sucked into that vacuum void at 100+ meters per second (225+ mph), slamming into pipe elbows or cast-iron valves like a hydraulic battering ram (Condensation-Induced Water Hammer). When the pipe wall shatters, 1,400 kPa (200 psi) superheated water flashes instantly into 1,600 times its volume in steam, blowing a 6-to-12-meter (20-to-40-foot) crater through the street asphalt and launching cobbles, manhole covers, and cars into the air.
5. The Chrysotile and Amosite Asbestos Mud Hazard:
6. Underground steam mains installed between the 1900s and 1979 were wrapped in thick thermal insulation blocks and insulating cement ("mud") containing 15 to 85 percent Chrysotile (white) and Amosite (brown) Asbestos.
7. While wet mud on the ground is non-airborne so long as it remains saturated with water, the moment the gray steam-blast slurry dries on pavement, car roofs, window ledges, or your shoes and coat, walking on it or brushing it releases millions of microscopic friable asbestos fibers into the air.

Comparison table: Underground Electrical Manhole Blast vs. District Steam Main Rupture vs. Natural Gas Main Leak¶

Step-by-step Asbestos Mud Decontamination Protocol after a Steam Pipe Explosion¶

If you were walking within 1 to 3 city blocks of a district steam pipe rupture (or if your apartment window was open toward the plume) and gray mud, dusty droplets, or fibrous debris landed on you or your property, follow the U.S. EPA / NYC DEP Emergency Asbestos Incident Protocol:

1. If You Are Directly Coated in Wet Mud or Dust Outside (Emergency Fire Department Decon Shower):
2. Do not get into a taxi, subway car, or your apartment building. Walk immediately to the Fire Department HazMat Decontamination Tents set up at the outer perimeter of the hot zone. Firefighters will have you bag your contaminated garments and valuables, walk through a warm-water decontamination shower, and put on a disposable Tyvek suit and hospital scrubs.
3. If You Already Walked Home Before Realizing the Mud May Contain Asbestos:
4. Stop in the entryway outside your apartment door (or on a hard tile surface just inside the door, never walk onto carpets or rugs).
5. Use a spray bottle of water or a wet paper towel to lightly mist your shoes and outer coat/clothing so dry dust cannot puff into the air as you undress (wet suppression).
6. Remove your shoes and all outer clothing (peeling garments inside-out rather than pulling a dusty shirt dry over your face), place them immediately into a heavy-duty plastic trash bag, seal the bag with duct tape, place that bag inside a second sealed plastic bag, and label it "HOLD FOR UTILITY ASBESTOS TESTING."
7. Wipe the entryway floor with wet disposable paper towels (never sweep with a dry broom and never use a household vacuum cleaner, as even a consumer vacuum without a certified sealed DOP-tested industrial HEPA filter blows microscopic 0.1-to-5-micron asbestos fibers straight through the exhaust into your room air).
8. Step straight into the shower and wash your hair and skin thoroughly with soap and warm water.
9. What Happens to Your Bagged Clothes, Car, and Apartment (Utility Liability):
10. Immediately after a steam blast, environmental scientists from the Municipal Department of Environmental Protection (DEP), State EPA, and the Steam Utility collect dozens of bulk mud and surface-wipe samples across the blast zone for Polarized Light Microscopy (PLM) and Transmission Electron Microscopy (TEM) testing (which takes 12 to 24 hours).
11. If tests come back Negative (0% Asbestos, modern fiberglass/mineral-wool pipe section): You can safely wash your bagged clothes and resume normal activity.
12. If tests come back Positive (>= 1% Chrysotile or Amosite Asbestos): The steam utility is 100 percent legally and financially responsible for hiring licensed Asbestos Abatement Contractors to wet-wash and HEPA-vacuum every street, building facade, window AC unit, and apartment interior in the fallout zone, reimburse you for all discarded clothing, carpets, and air-conditioner filters, and pay for your hotel and meals until an independent air monitor certifies clearance under the AHERA TEM standard (< 70 structures/mm2).

Regional emergency numbers and urban underground infrastructure agencies¶

• United States and Canada:
• Emergency Dispatch: Dial 911 immediately for any smoking, sparking, or chattering manhole cover, underground vault explosion, or high-pressure steam geyser.
• New York City (Largest Underground Steam & Network Grid in the World): Call 911 (FDNY & NYC OEM), Con Edison 24-Hour Steam & Electric Emergency at 1-800-75-CONED (1-800-752-6633), and check 311 / nyc.gov/dep (NYC Department of Environmental Protection) for real-time asbestos sampling boundaries after a steam main rupture.
• Boston, Philadelphia, Baltimore, Denver, & Seattle: Call 911 plus Vicinity Energy (operates district steam in Boston, Philadelphia, and Baltimore) or Enwave (Seattle, Chicago, Toronto) and your local electric utility (Eversource, PECO, BGE, Xcel, ComEd, Toronto Hydro).
• Federal Asbestos & HazMat Reporting: U.S. EPA National Response Center (NRC) at 1-800-424-8802 (mandatory reporting for releases of >= 1 pound / 0.45 kg of friable asbestos under CERCLA 40 CFR Part 302).
• United Kingdom:
• Emergency Dispatch: Dial 999 for any pavement link-box explosion, smoking manhole, or district heating rupture, and dial 105 to reach the regional Electricity Distribution Network Operator (UK Power Networks in London).
• London Pavement Vaults & Asbestos: Regulated by the Health and Safety Executive (HSE) under the Electricity Safety, Quality and Continuity Regulations 2002 and Control of Asbestos Regulations 2012.
• European Union:
• Emergency Dispatch: Dial 112 across all EU member states.
• Paris (CPCU High-Pressure Steam Network & Enedis Vaults): Paris operates one of Europe's largest high-pressure underground steam grids (Compagnie Parisienne de Chauffage Urbain / CPCU). Call 18 or 112 (Sapeurs-Pompiers de Paris) and CPCU Urgence Vapeur (01 44 68 68 20) or Enedis (09 72 67 50 75).
• Germany & Northern Europe: Call 112 (Feuerwehr) for underground cable vault (Kabelschachtbrand) or district heating (Fernwärmeleitungsbruch, typically superheated pressurized water at 110 to 140 C) ruptures.
• Australia, New Zealand, and Asia:
• Australia & NZ: Dial 000 (Ausgrid 13 13 88 in Sydney CBD / CitiPower 13 12 80 in Melbourne CBD) or 111 (Vector in Auckland CBD) for underground pit/vault fires.
• Singapore, Hong Kong, & Tokyo: Dial 995 (SP Group 1800-778-8888 in Singapore), 999 (CLP / HK Electric in Hong Kong), or 119 (TEPCO in Tokyo).

Frequently asked questions¶

Why did my apartment's Carbon Monoxide (CO) detector go off when there is no gas stove or furnace in my apartment, just a smoking manhole outside on the street?¶

Your `CO` detector just saved your life. When an underground electrical cable catches fire inside a street manhole or conduit bank, the burning rubber, polyethylene, and oil-impregnated paper insulation undergoes oxygen-starved thermal decomposition (pyrolysis), generating massive concentrations of pure, odorless Carbon Monoxide (`10,000 to 50,000+ ppm`). Because underground electrical conduits run directly from the street manhole into your building's basement service box, the high pressure inside the burning vault pushes that Carbon Monoxide straight into your basement and up through elevator shafts, stairwells, and radiator pipe chases, while the earth and conduit walls filter out the visible smoke and smell. Evacuate the building immediately, call `911`, and tell firefighters there is an active underground electrical fault pushing `CO` into your building.

How can I tell the difference between harmless winter condensation rising from a manhole and a dangerous underground cable fire or steam main leak?¶

Check four things from a safe distance on the sidewalk: (1) Color and Density: Harmless winter vapor (cold rainwater hitting a warm pipe) is thin,wispy, translucent white mist that disappears within `1 meter` (`3 feet`) of the grate; an electrical manhole fire produces thick, opaque gray, black, or yellowish-brown smoke, while a steam main rupture shoots a roaring, pressurized white jet several meters into the air. (2) Odor: An electrical cable fire smells strongly of burnt tar, melting plastic, or acrid rubber. (3) Sound: A failing electrical vault or steam pipe emits a loud `120-Hz` hum, crackling, banging, or a high-pressure hiss/roar. (4) Cover Movement: If the cast-iron cover is vibrating, chattering, or bubbling boiling water around its rim, evacuate `30+ meters` (`100+ feet`) and call `911` immediately.

If a steam pipe explodes on my block and coats my parked car in gray mud, can I drive my car away or take it through a car wash?¶

No, never open the doors, turn on the air conditioning, drive, or take a mud-splattered car inside a commercial car wash after an urban steam pipe explosion until environmental authorities (`DEP` / `EPA`) confirm whether the mud contains asbestos. If the ruptured steam main was insulated with pre-1980 Chrysotile or Amosite Asbestos, opening the car door drops dry fibers onto your seats, turning on the dashboard blower sucks asbestos dust into the cabin air filter and evaporator core, and driving the car spreads regulated hazardous waste outside the hot zone. Leave the car parked inside the cordon: if tests confirm asbestos, the steam utility's licensed abatement contractors must decontaminate your vehicle (and replace the cabin filter or total-loss the interior if windows were open) at the utility's expense.

Why do manhole explosions happen most often at the end of a winter snowstorm or during a July heatwave?¶

Underground electrical grids suffer two seasonal stress peaks: (1) The Late-Winter "Road Salt Thaw" (`February-March`): When cities spread tons of sodium chloride road salt on snow, the melting salty slush pours through manhole vent holes into underground vaults and coats aging cable splices. Saltwater is a powerful electrical conductor that corrodes lead sheaths and triggers violent electrical tracking and arcing across deteriorated insulation, causing a surge of "manhole seasons" every late winter. (2) The July Heatwave Peak: When millions of air conditioners run simultaneously while hot asphalt bakes the ground above, underground copper cables reach `90+ degrees Celsius` (`195+ degrees Fahrenheit`), causing thermal expansion, joint failure, and insulation pyrolysis.

If my apartment windows were closed during a steam pipe explosion outside, could asbestos dust still get inside my apartment?¶

If your windows were tightly closed and you did not run a window air conditioner on the "Fresh Air / Vent" setting or track mud inside on your shoes, the interior of your apartment is usually well protected because the initial steam-blast fallout is wet, heavy slurry that settles onto exterior ledges and sidewalks. However, do NOT open your windows, do NOT touch or clean your exterior window sills, and do NOT turn on a window air-conditioning unit until the municipal `DEP`/`EPA` announces whether the blast contained asbestos. If asbestos is confirmed, the utility's abatement crew must wet-wipe your exterior window frames and either decontaminate or replace your window AC unit at zero cost to you.

Who pays for my hotel room, ruined clothes, and business interruption if a utility manhole fire or steam pipe blast forces a multi-day evacuation?¶

First, during an active asbestos or structural evacuation ordered by the city after a district steam pipe rupture, utilities (such as Con Edison in New York) set up an Emergency Claims & Relocation Center at a nearby hotel or school to provide immediate hotel vouchers, per-diem meal allowances, and replacement clothing allowances for displaced residents. Second, check your **Renters Insurance (`HO-4`), Condo Insurance (`HO-6`), or Homeowners Policy (`HO-3`)** under the **"Loss of Use / Additional Living Expenses (`ALE`) - Civil Authority Prohibits Use"** clause: whenever a Fire Department or municipal agency orders mandatory evacuation of your street due to physical damage at a neighboring utility premise, your policy's `ALE` coverage reimburses your hotel, restaurant meals, and pet boarding immediately while your insurer subrogates against the utility.

Related guides¶

• District steam pipe explosion, manhole fire, and underground vault blast
• Stray voltage on metal streetlights, sidewalk manhole covers, and dog-walking shocks
• Natural gas odorant mercaptan fade, odorless underground gas migration into basements, and explosive limits
• Pad-mounted green transformer box in yard buzzing, leaking mineral oil, or exploding
• Emergency numbers by country

Sources and official guidance¶

• U.S. Occupational Safety and Health Administration (OSHA) & Institute of Electrical and Electronics Engineers (IEEE): 29 CFR § 1910.269(e) (Enclosed Spaces / Underground Electrical Vaults and Manholes) and IEEE Working Group on Secondary Network Vaults and Manhole Events (Pyrolysis of PILC/XLPE Cable Insulation, Carbon Monoxide Generation, and Vented Manhole Cover Mitigation).
• U.S. Environmental Protection Agency (EPA) & New York City Department of Environmental Protection (NYC DEP): CERCLA Hazardous Substance Release Reporting (40 CFR Part 302, 1-lb Reportable Quantity for Friable Asbestos), NESHAP Asbestos Standard (40 CFR Part 61 Subpart M), and NYC DEP Title 15 Chapter 1 (Emergency Asbestos Incident Assessment, Wet-Decontamination, and AHERA < 70 s/mm2 TEM Air Clearance Protocols).
• Fire Department of the City of New York (FDNY) & National Fire Protection Association (NFPA): FDNY Underground Electrical Manhole / Transformer Vault Fire and Basement Carbon Monoxide Migration Tactical Operating Procedures and High-Pressure District Steam Main Rupture Response.
• National Institute for Occupational Safety and Health (NIOSH / CDC, United States): Immediately Dangerous to Life or Health (IDLH) Concentration Profiles for Carbon Monoxide (1,200 ppm) and Asbestos Fiber Decontamination.
• Health and Safety Executive (HSE, United Kingdom): HSG47 (Avoiding Danger from Underground Services), ESQCR 2002 (Underground Link Box and Pavement Vault Explosions), and Control of Asbestos Regulations 2012.