Gas and Carbon Monoxide Awareness

Photo from the September 9, 2010, San Bruno, California, natural gas pipeline explosion. Eight people died in the blast. (Photo found on Wikimedia Commons courtesy of Brocken Inaglory.)


By Daniel P. Sheridan

As we enter into the upcoming winter months, there will be many stories of gas leaks and carbon monoxide (CO) emergencies filling the pages of our daily newspapers and on our smart phones. The fire service will be dealing with the aftermath of incidents such as house explosions and CO illnesses.

CO is measured in PPM in any given atmosphere. Occupational Safety and Health Administration regulations deem that any exposure over 35 PPM in any eight-hour period is considered mild. CO is colorless, odorless, and tasteless. The only way to measure its presence is with a meter or, unfortunately, when people start exhibiting symptoms such as headaches, dizziness, and nausea. As a young firefighter, I had been exposed numerous to CO numerous times. It is a horrible feeling; usually after a decent exposure, I would need a few days to recover. The greatest, most obvious symptom is a splitting headache.

There are now products on the market today that can help first responders avoid responding to a potentially dangerous situation. These gas sensor/CO systems are commercially available to the general public. The gas sensors can detect a gas leak such as liquefied petroleum gas or natural gas and alert you of the dangerous buildup within your home.  These gas sensors can also send a wireless signal to a small shutoff valve installed within the home that shuts off the gas to appliances.  This alerts you and begins to mitigate the problem before it can reach the lower explosive limit (LEL), making it safer for first responders.  

These gas systems adhere to European standard EN 50294, which doesn’t exist in the U.S. The CO system adheres to EN 50291, which detects the CO danger at a lower concentration of 30 parts per million (PPM) and will shut down CO producing appliances within two hours.  It may be worthwhile for chiefs to advocate for this system to be put into code in their districts.

Many people today are mildly exposed to gas and they don’t even realize it. The average CO alarm follows the UL 2034 Standard, which allows you to be exposed to up to 70 PPM for a month before it sounds.

Just in the last two months, the following three stories happened here in the U.S.:


In Putnam County, New York, a house explosion injures a young pregnant mother

9/3/14—A home on Route 301, just past Glynwood Farm, is nothing but charred remains after a fire early Sunday. As of 10 a.m., there were still wisps of smoke coming off the fireplace, the only portion of the house that was still, barely, standing. The garage had collapsed on top of a car as a result of the flames.

Read more HERE



One confirmed dead in East Brunswick, New Jersey, house explosion

9/17/14—Hours after the overnight home explosion that witnesses say rocked an East Brunswick neighborhood, the Middlesex County prosecutor’s office has confirmed that emergency teams discovered a body at the scene.

Investigators recovered the body during a search of the house at 4 Agate Road Wednesday afternoon. The man’s name is being withheld pending confirmation of his identity with his next of kin, said officials.

Read more and see photos HERE



In Cincinnati, Ohio, a Mother, daughter are saved from carbon monoxide poisoning

10/6/14—As weather in the Tri-State took its first dip to near freezing temperatures over the weekend, Cincinnati crews responded to their first home emergency involving carbon monoxide (CO).

A woman coming home to her apartment complex in the 2000 block of Stratford Avenue said she heard her downstairs neighbor calling out for help.

Read more and watch video HERE


Although gas is safe and clean, it still remains a volatile substance. Natural gas is lighter than air. Depending on the exact composition, it has a vapor density of 0.59 to 0.72, a LEL of 3.9 percent to 4.5 percent, and an upper explosive limit (UEL) of 14.5 percent to 15 percent. Its ignition temperature is 483°C to 632°C (900°F to 1,170°F). That means that if you have a leak in an appliance and the gas fills the space to these explosive levels, the results are catastrophic.

The same holds true for propane, which is heavier than air. It has a vapor density of approximately 1.5 to 2.0, a lower explosive limit (LEL) of 2.15 percent, and an upper explosive limit (UEL) of 9.6 percent. Its ignition temperature is 493°C to 604°C (920°F to 1,120°F). When the propane or the natural gas comes in contact with any type of ignition source, you will have a devastating explosion. The ignition source can be anything from a pilot light to a static charge.

As the weather gets colder, it will be more difficult for gases to migrate upward into the atmosphere and dissipate. For example, USA Today on January 16, 2014, printed, “As the use of natural gas booms in the United States, scientists are testing for pipeline leaks. They found more than 5,800 leaks under the streets of Washington, D.C., some potentially explosive.”

The State of Massachusetts thought enough of the problem to put into law a bill requiring gas companies to address the situation and repair the leaks.

The following press release was issued on July 7, 2014, on

Boston, Mass., July 6th, 2014 – Mark McDonald has waited for this day for a long time.  As the President of the New England Gas Workers Association, he wrote legislation in 2010 that would reduce the risk of natural gas pipeline explosions in Massachusetts by forcing natural gas companies to improve the state’s response and repair of gas leaks on their aging pipeline infrastructure.  Finally, after years of lobbying marked by thousands of reported gas leaks and dozens of explosions statewide, McDonald’s bill is hours away from being signed into law by Governor Deval Patrick tomorrow, July 7th at 11:15 AM at Springfield City Hall, 36 Court Street, Springfield.

To draw attention to the scope of the problem and urge Governor Patrick to sign the bill into law, McDonald and victims of former Massachusetts gas explosions have unveiled the first-ever gas leak map showing the precise location of more than 300 gas leaks in the city of Medford, Mass as of 2010.  The coalition will reveal a new map featuring a new city or town each month, showing how many hundred, in some cases thousands, of gas leaks that exist in each city.  The map will show the precise locations of some leaks that were identified as early as 1984 and haven’t been fixed since. “We’re releasing this map, city-by-city, because we want residents to know how widespread the problem is,” said McDonald.


According to NFPA 921 section & 2: It is common for fuel gases that have leaked from underground piping systems to migrate underground (some- times for great distances), enter structures, and create flam- mable atmospheres. Both lighter-than-air and heavier-than-air fuel gases can migrate through soil; follow the exterior of underground lines; and seep into sewer lines, underground electrical or telephone conduits, drain tiles, or even directly through basement and foundation walls, none of which are as gastight as water or gas lines. Such gases also tend to migrate upward, permeating the soil and dissipating harmlessly into the atmosphere. Whether the path of migration is lateral or upward is largely a matter of which path provides the least resistance to the travel of the fugitive gas, the depth at which the leak exists, the depth of any lateral buried lines that the gas might follow, and the nature of the surface of the ground. If the surface of the ground is obstructed by rain, snow, frozen earth, or paving, the gases may be forced to travel laterally. It is not uncommon for a long-existing leak to have been dissipating harmlessly into the air until the surface of the ground changes, such as by the installation of new paving or by heavy rains or freezing, and then be forced to migrate laterally and enter a structure, fueling a fire or explosion.

I have responded numerous times to assist our local utility company to gain entry into basements of houses that are effected by a gas leak in the street. Many of those times we have found houses closest to the leak with levels as high as 2%. The problem usually is greatest in the sleeping hours. The danger is when the gas accumulates in basement and people are unaware of the situation. Another possibility that may exist is if the odorant (Mercaptin) gets washed out, now we have an odorless and colorless gas entering our residences.


According to NFPA 921 section  A&B

(A) Loss of Odorant Due to Gas Migration in Soil. Gas odorants can be removed by dry, clay-type soils, and not by sand, loams, or heavily organic soils. Certain odorant components are better than others in terms of their ability to resist adsorption by clay-type soils. A large leak gives a lower contact time with the clay-type soil, and results in lower losses due to adsorption.

(B) Loss of Odorant Due to Adsorption of Odorant on Pipe Walls. All odorant components are adsorbed by pipe walls to some extent. This is particularly true of new pipe (steel or plastic). Many natural gas companies treat the gas in new sections to a heavier dose of odorant after the section is placed in service. Gas odorants can be adsorbed in gas pipe that has been in continuous service, if the flow rates of gas are lower than normal. This is a typical condition in many gas companies in the transition between winter and summer usage levels. A decrease in pressure in the system, which increases gas flow rates, easily remedies this problem. Any portion of a gas system that is subject to low flow rates is subject to increased loss of odorant due to adsorption.


Carbon Monoxide Safety Standards and Exposure Limits


When you respond to these types of emergencies, it is critical that you have in your possession a meter that measures the levels of gas in the atmosphere.

For more regarding the dangers of CO, October is Fire Prevention Month. Generally, local fire departments will encourage people to change the batteries in their smoke and CO alarms when the clocks turn back.

With the approaching heating season, we will now be hearing more about CO emergencies. CO is a result of incomplete combustion. When you turn on your heating appliances, the burner should have sufficient oxygen to produce carbon dioxide; this will appear as a blue flame. When the heating unit is clogged or dirty or not receiving enough oxygen to sustain a clean burn, a yellowish flame will be produced and CO willl result. If there is a blockage in a flue pipe or chimney, a crack or any other situation that would not allow the gases to vent out into the atmosphere willl create a buildup of CO.

It is extremely important that first responders—especially emergency medical services (EMS) crews—have in their possession CO meters when responding to any type of emergency. It is of paramount importance that when a call is received for a possible CO exposure, these meters are with the EMS personnel.


Daniel P. Sheridan is a battalion chief for the Fire Department of New York.

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