The following article was written by Russell Warn and published in ISHN magazine (ishn.com), December 2016. Roco comments have been added to the article and are noted in red.

Working in confined spaces presents a unique and dangerous challenge in combatting the unseen – oxygen deficiency, poisonous or explosive gases, and other hazardous substances are among the most frequent causes of accidents associated with work in confined spaces and containers.

From 2005-2009, the Bureau of Labor Statistics reported nearly two deaths per week, or roughly 96 per year, could be attributed to confined space, with about 61 percent occurring during construction repair or cleaning activities.

With conditions subject to change in a moment’s notice, taking steps to protect against life-threatening dangers should always be a top priority in confined spaces. Performing a thorough clearance measurement is a demanding — yet crucial — task that dictates the safety environment, and should not be taken lightly. To help guide you along your road to enhanced safety, outlined below are several best practices based on frequently asked questions.

When should I perform a clearance measurement?

Conduct clearance measurements immediately before operations begin. Environmental factors such as temperature and air flow can change the atmosphere, causing readings to fluctuate. One shift’s measurement taken at 7 a.m. is not representative of the conditions when work operations commence for another shift at 4 p.m. New clearance measurements must be taken immediately to account for the nine hours of changing temperatures and ventilation patterns, depicting the accurate readings of present conditions.

Roco Comment: In addition to pre-entry clearance measurements, entry into permit spaces during construction activities requires "continuous atmospheric monitoring" unless the entry employer can demonstrate that equipment for continuous monitoring is not commercially available or periodic monitoring is sufficient. Ref. 1926.1203 (e)(2)(vi), 1926.1204 (e)1)(ii), and 1926.1204 (e)(2). Additionally, Roco believes that for "ALL" permit entry operations, it is advisable to provide continuous atmospheric monitoring no matter what the industry activity entails.

What’s the importance of zero-point adjustment?

When performing clearance measurements, it’s crucial to determine the reference point of the gas detector by calibrating the zero-point. The zero-point ensures that the indicated values correspond to the actual existing gas concentrations. In order to determine that the actual zero-point has been found, calibrate equipment in an environment where the hazardous substance is not present, such as fresh air environments. With every scientific test, no matter the field, a control group, which serves as a starting point of reference, permits for the comparison of results to show any contrasting changes. The zero-point calibration acts as such, allowing workers to identify the presence, or lack thereof, of different gas concentrations.

Where do I measure/take the sample?

When it comes to measuring samples, there are four things to keep in mind: the physical properties of gases, and the type and shape, temperature and ventilation patterns of the confined space.

Know the differences between light and heavy gases. Clearance measurement experts must have a strong working knowledge of hazardous substances’ properties, as they play a role in where measurements should be taken. For example, if a sample is pulled from the top of the confined space and hydrogen sulfide (H2S) is detected, the sample may not be entirely reliable. H2S has a molar mass of 34 g/mol, which is significantly heavier than that of air (29 g/mol). As a result, H2S sinks to the bottom of a space, where its concentration would be greatest. Identifying a presence at the top of the confined space says immediate danger and appropriate actions should be taken.

Light gases quickly mix with air and rise to the top. As a result, any measurements in open atmospheres should be performed close to the leak, and increases in concentration should appear in the highest points of the confined space. Heavy gases, on the other hand, should sink and flow like liquids, pass obstacles or stick to them. They barely mix with air like light gases do, so their samples should always be taken at the lowest points of the confined space.

Determine the type/shape of the confined space: In an ideal scenario, each confined space area would be in an “even” or level position. This isn’t always the case, and a container may be placed on an inclined surface, making the highest point in the corner positioned toward the top of the inclined surface. Thus, entry may be nearer to where the heavy gases have accumulated.

Take tabs on temperatures. All matter is made up of atoms and molecules that are constantly moving. When heat is added to a substance, such as a gas, the molecules and atoms vibrate faster. As the gas molecules begin to move faster, the speed of diffusion increases. If the sun has been shining on a tank for hours, there’s a good chance the clearance measurement taken at dawn no longer reflects the current readings due to the increase in diffusion.

Vet the ventilation. Air currents change the position and concentration of air clouds, and often times, the way a confined space is ventilated can affect readings. Containers cannot always be separated from pipelines, or there may be leaks in the tanks that must be accounted.

Roco Comment: Not only is it required by certain OSHA provisions like alternate entry procedures, but Roco highly recommends monitoring the atmosphere prior to initiating ventilation. This is intended to provide a reasonable assessment of the potential atmosphere change should the ventilation equipment fail. The rate for a potential hazard to re-develop will be based on factors such as the effectiveness of isolation, any residual product within the space, temperature, humidity and passive ventilation which are among just some of the factors.

How do I safely conduct the measurement for an accurate reading?

People often question why they can’t just use the carrying strap of their device to lower the device into the confined space for a reading. Although this seems like a simple fix, it’s not a safe or recommended way to conduct the measurement. Lowering the device into the container this way not only obscures the way the display is read, but it may not audibly alarm. If the measured value is slightly below the threshold value and the alarm does not sound, a worker would not be notified of the dangerous concentrations lurking below. Not only this, but measurements may be inaccurate since the measured gases, due to their molar masses, may be concentrated at a higher or lower point within the container. Clearance measurements should be conducted on-site and on-the-ground of the confined space for accurate, safe readings.

Roco Comment: The points made in the preceding paragraph are certainly valid. The best solution that we can offer is to use remote sampling probes or tubes to actively draw (pump) samples from the stratified levels of the space while the direct reading instrument is in a position outside the space to observe the real time readings. To expound upon the point the author makes, if the pre-set threshold for the alarms are not enough to trigger the alarm indicating the presence of a hazardous atmosphere, and the individual performing the assessment relies instead on rapidly pulling the monitor from the space in the hope that they are able to read the display before the values change, is a very dangerous way of approaching this procedure. Depending on the sampling rate of the monitor, the hazardous gas(s) may have cleared from the monitor in the time it takes to withdraw it from the space, and it is very likely that the instrument will display a normal atmosphere by the time it is back within view. Additionally, for areas within the space that cannot be remotely assessed by remote sampling prior to entry, the only safe recourse is to limit entry to the areas that have been assessed and to take a monitor into the space to continuously assess the unreachable regions before venturing further.

What do I need to document during clearance measurement protocols?

Just as it’s important to remain thorough in clearance measurements procedures, it’s equally as important to remain thorough in the general housekeeping protocols surrounding samples. This includes documenting:

• • The container number
• • The measuring point of the container, and whether there was more than one measuring point
• • At which time was the clearance performed
• • Under what condition was the measurement performed
• • Measured hazardous substances
• • Name of person performing measurement
• • Equipment used for clearance

Safety, regardless of job title or responsibility, should be everyone’s top priority. When working in the midst of poisonous and explosive hazards, performing clearance measurements correctly and carefully means not only keeping one’s self safe, but keeping the working environment safe, as well.

About the Author:
Russell Warn is the product support manager for gas detection products at Dräger. He has been in the safety industry for more than 29 years, with most of this time dedicated to gas detection product and application support.

By Josh (JC) Hill, Roco Technical Equipment Manager & Chief Instructor

As mentioned in our original story, the alarming statistic of confined space fatalities still proves to be accurate – approximately 60% of fatalities in multi-casualty incidents are the “would be rescuers.” In January, it happened once again. Four construction workers had entered a drainage manhole to determine why the newly paved road was settling in that location.

Upon entering the space, which is believed to have been done without initial monitoring or ventilation, the worker collapsed. As is seen much too often, a second worker entered the space to assist the downed worker and was rendered unconscious. A third worker entered the space and again succumbed to the atmosphere.

The 911 system was activated and responders from the Key Largo VFD arrived at the scene and prepared to enter the space to perform rescue. Initial reports state that a volunteer firefighter donned an SCBA for respiratory protection and attempted to enter the manhole. He found the space to be too confining and removed his SCBA to make entry. He was in the space for approximately 20 seconds prior to being overtaken by the atmosphere. Note: It is our understanding that proper monitoring of the confined space had still not occurred at the time of the firefighter’s entry to attempt rescue.

Another firefighter then entered the space and recovered the first firefighter from the deadly space. Medical attention was provided until he was airlifted to Jackson Memorial Hospital’s Ryder Trauma Center. The Miami-Dade County Haz-Mat Team was also called to the scene.

After proper monitoring of the space, it was determined that rescue was no longer a viable option and that the scene would be transitioned to recovery efforts. The testing of atmospheric conditions showed the space contained significant levels of hydrogen sulfide and methane gas with decreased levels of oxygen.

Although original reports did not give indication of toxic gases, the signs surrounding the events make it obvious that the potential was there. To have several workers enter a space like this and rendered unconscious in short periods of time is a classic scenario involving atmospheric hazards. This combined with several statements from neighbors that the area smelled of “rotten eggs” for months provide significant clues to atmosphere being a significant contributing factor to the emergency.

So, why do these confined spaces incidents continue to occur across the nation with emergency responders?

When you break it down, the reasons are fairly simplistic and very alarming. Most citizens have a misconception of fire departments and emergency responders. Most often, it is assumed that if you call the fire department, whether in a large municipality or small township, the personnel responding will be qualified and equipped to perform any task needed.

Fact is the vast majority of fire departments are trained and equipped to perform basic first aid and life support along with standard firefighting operations.

Funding has and will continue to be the major handicapping factor that limits the capabilities of these agencies. Unfortunately, it usually takes a catastrophic event before funding is provided.

Also, unless dedicated specialty teams are established, it is practically impossible for agencies to train each individual to a proficient level for technical rescue and hazardous material response and have them maintain this level without regular, on-going training. It is also unrealistic for departments to outfit each individual responding unit with all of the necessary equipment to respond to every conceivable scenario.

As we all know, emergency responders are built around running towards the danger when human life is at risk. This attitude is what separates them from the average population and makes them successful at protecting life and property.

However, when not properly trained to react and respond to these types of uncommon hazards, the results are often as unfortunate as what we witnessed in Key Largo.

So, how can we change these alarming statistics for emergency responders?

First of all, it is critical that responders understand the unseen hazards they could be exposed to during these types of hazardous confined space operations. It is imperative that all personnel – from the newest rookie to the incident commander – understand what they are facing. Emergency responders must be able to recognize when they are not adequately trained or equipped for an event or hazard. They must understand that their lives are on the line in these hazardous environments.

Firefighters, from the smallest volunteer departments to the largest municipalities, must be trained to recognize the signs of hazardous environments and understand that they would be putting themselves in grave danger if they proceed with rescue attempts. Supervisory personnel should receive additional training that provides the knowledge to understand their full capabilities when facing scenarios they are not properly trained and equipped to safely handle. To stand-down is the wisest decision to protect their personnel from severe injury or death when the chances of successfully performing rescue have little to no chance for success.

It’s a difficult choice – risk vs. reward. But it’s a critical decision that emergency responders must make every day. Their personal safety must come first – it must be a viable rescue before they put themselves in harm’s way.

KEY LARGO, Fla. - Three workers in the Florida Keys died Monday morning (Jan 16) after they were overcome by fumes, authorities said. Miami-Dade Fire Rescue officials said they responded to reports of three people down. The victims were working at a road project.

A representative said a worker went inside a drainage manhole to see why the newly-paved Long Key Road was settling at that location. She said the worker got trapped inside the manhole and three other workers, a volunteer firefighter with Key Largo Volunteer Fire Department and two Monroe County Sheriff's Office deputies tried to help get him out.

The two workers who collapsed and the firefighter, who also collapsed after going underground, were pulled from the hole, authorities said. The two workers were pronounced dead at the scene. It took authorities several hours to recover the body of the third worker. The firefighter and deputies were taken to Mariners Hospital in Tavernier.

The firefighter, identified by relatives as Leonardo Moreno, was then airlifted to Jackson Memorial Hospital's Ryder Trauma Center, where he is listed in critical condition.

"A firefighter had an air pack on," Monroe County Sheriff Ramsey said. "He found the hole too small, so he elected to take his air pack off and go inside the hole to attempt the rescue."

The deputies are being treated for non-life-threatening ailments. A fourth worker for the contractor was treated at the scene.

Cause of deaths will be determined by the Monroe County medical examiner.

A woman who lives near the manhole told Local 10 News that the area has smelled of rotten eggs for the past couple of months.

The contracted workers were in a 15-foot hole and it's believed that a build-up of hydrogen sulfide and methane is to blame for the deaths.

"There's no sign of any pre-venting going in, and obviously going into a contained environment where there is gases can be deadly, as we unfortunately found out today," Ramsey said.

Records show that the contractor was fined for an incident at a manhole in Collier County in 2002. In that case, OSHA said workers were exposed to hazardous conditions.

UPDATE: We are glad to report that the firefighter involved in this incident has been taken off the ventilator and is breathing on his own with no neurological deficits shown so far. This information is according to the latest update on his gofundme page https://www.gofundme.com/leomoreno

SOURCES: WPLG Local10.com and Firefighter Nation.

By Pat Furr, Safety Officer & VPP Coordinator for Roco Rescue, Inc.

Oxygen-Depleted Atmospheric Hazards in Confined Spaces

It will take your breath away! This is a phrase often used to describe tremendous beauty, or exhilaration. However, in an oxygen-depleted environment, this phrase has a much more ominous meaning. The emotion it elicits is hardly pleasant and joyful. Confusion, panic, impending doom, and okay... maybe even euphoria, which has been reported in near drowning cases, but the euphoria is a late onset emotion once the brain is deprived of oxygen. Suffice to say, having your breath taken away in an oxygen-depleted environment is never a good thing!

In my prior career with USAF Pararescue, I underwent regularly scheduled physiological training in an altitude chamber; otherwise, known as a hypobaric chamber. This was used to train me to recognize the onset of hypoxia (low physiologic oxygen content) and the symptoms that are particular to me. The symptoms of hypoxia differ from person to person and mine were pretty subtle. A loss of peripheral vision and color acuity, a slight warming of the sides of my neck and face, but other than those symptoms, I didn’t have any dramatic, obvious clues that I was in trouble. On at least two occasions, I had to be told by the chamber operator to don my oxygen mask. Once I did, the return to normalcy was profound! I was then able to jot down my symptoms as I remembered them. As I was undergoing my slide into hypoxia, I was given basic written tests to perform such as simple addition problems, connecting the dots, finishing incomplete squares and circles. In every case, I thought that I was doing really well on my assignment; that is until my oxygen mask was returned and I reviewed my work. FAIL!!! This exercise was intended to demonstrate to me the insidious nature of hypoxia and the unrecognized affects it has on coordination and judgment.

My experiences in the altitude chamber were educational and potentially lifesaving if I were ever exposed to a low oxygen environment. By having experienced my subtle symptoms multiple times, perhaps I would recognize them in a lower than normal oxygen environment and be able to take action to rescue myself. However, the environment that I was exposed to was probably in the range of 12% oxygen by volume give or take. In lower concentrations, say below 10%, the onset of impaired judgment would be so rapid that I would have little chance to recognize and react on my own behalf. In extremely low concentrations of 0-8%, there is little chance for anyone to take self-rescue actions. More than likely, the individual will pass out after only one or two gasping breaths. And, most importantly, my experiences were in a controlled environment with highly trained observers and emergency personnel standing by. This is not always the case during confined space entry operations.

How do we end up with depleted oxygen concentrations in confined spaces? 

There are several ways, but I am going to address two broad categories of occurrence: (a) planned, and (b) unplanned. Planned low oxygen concentrations may be unavoidable when doing entries that require an inert gas environment, such as certain types of welding or when doing work in a flammable or explosive atmosphere. By removing the oxygen, one of the three elements of flame is eliminated. There will remain fuel and possibly a source of ignition, but by removing the oxygen, there is no potential for fire in nearly every instance. Even during planned oxygen depleted operations, things have a potential to go wrong. Equipment failure is one possible cause. Faulty supplied air breathing systems can be the culprit. It may be as simple as a failed “O” ring, a faulty diverter valve, a lost connection on an airline respirator system, and many other links of equipment. Or, it could be human error – such as not tending airlines and causing the mask to be dislodged or pulled completely off; failure to change out bottles on the SAR cart; exceeding the safe time and egress requirements if using backpack SCBA; or again, any number of human failures. So you can see that even during planned low O2 entries, the potential for an incident is quite high. That is why OSHA 1910.134 has such stringent requirements for entry into an atmospheric IDLH environment.

It is the unplanned depleted oxygen environments that seem to cause the most incidents, however. Within unplanned low O2 entries, I would like to further categorize them into two separate areas.

1. Unplanned...in that the atmospheric hazard was thought to be controlled, but the potential for the hazard to appear was realized, and indeed created the low oxygen hazard. This could be due to improper isolation techniques or equipment failure.
2. Unplanned and unanticipated...this is the one that really seems to be causing problems. It may happen in permit-required confined spaces and also in non-permit required confined spaces. Upon evaluation, the entry team may have identified the space as non-permit required and assumed there was no need to perform pre-entry atmospheric monitoring. In several incidents, unbeknownst to the entry team, a prior entry team introduced an inert gas into the space for their particular work activities and failed in two ways. The team did not ventilate the space to remove the inert gas and test it afterwards; and, more importantly, the prior entry team failed to communicate the presence of the inert gas to any potential follow-on entrants. Or it may be that the information regarding the inert gas was communicated, but that information was lost in the shuffle. It may have never made it to the follow-on entry team – or that team may have failed to properly process the information. As you can imagine, this type situation has not only led to the demise of the unaware follow-on entrant, but also to several would-be rescuers that attempted rescue without any clue that the oxygen concentration was at a lethal level.

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So what is the solution? 

Although this simple step will not “guarantee” a safe entry operation, I know for a fact that by simply employing an atmospheric monitor to test for oxygen will save many lives. And, don’t limit the use of atmospheric monitors for entries into known or potentially low O2 atmospheres! That is an OSHA minimum, so why not exceed that minimum requirement and get into the habit of testing the oxygen concentration for ALL entries? And, not just for permit-required spaces, include non-permit spaces as well. You just never know. Also when monitoring, don’t forget to test the various levels of the space and all breathing zones. Various gases tend to stratify, some being heavier than air, and some lighter, while others are nearly equal and will diffuse universally. Maintain your monitors, calibrate them and bump test them as required by the manufacturer and use them regularly. They are easy to use and relatively inexpensive. They have saved many lives and will continue to do so, if used properly.

Be safe out there and monitor, monitor, monitor!

Although this article has focused on low oxygen atmospheres, we do not mean to minimize the potential for other hazardous atmospheres, such as toxic or flammable. It is just our experience that of all the hazardous atmospheres, it seems that low oxygen is the one that crops up more often and continues to claim a disproportionate number of entrants AND would-be rescuers.

Readings are 20.9/0/0/0…so it must be safe for entry, right? Not necessarily!

After completing an interesting confined space standby job for Roco, I wanted to caution rescuers about the possibilities of atmospheric hazards within a confined space – despite what the atmospheric monitor says!

For this particular job, the atmosphere in the workspace never varied on the 4-gas monitor readings. The readings were consistently 20.9% for O2; 0 for LEL; 0 for H2S; and 0 for CO. However, this entry required the use of air-purifying respirators even though there were no visible signs of anything unusual – no odor, no product warning signs, no indication that there may be an inhalation hazard in the space.

This particular space was located at a public water facility. It was a 70-ft. deep concrete metering pit with six consecutive 12-ft x10-ft levels. It had concrete floors and walls with a vertical ladder that accessed each level. Although the space was not designed to store any product, in this case, we still had an atmospheric hazard.

The purpose of the entry was for remediation of mercury contamination on the concrete surface. The gross cleanup of liquid mercury had been performed years prior, but further action was required to eliminate vapor hazards still present in the lower chambers.

During the first phases of the entry, vapor levels that exceeded 40,000 ng/m3 (nano-grams per cubic meter) were detected. The more frequently updated ACGIH Threshold Limit Value is only 25,000 ng/m3. The work environment in this space routinely approached twice this level, even though there were no visible signs of liquid mercury. The source of the toxic atmospheric hazard was invisible and odorless – mercury vaporizing from the concrete surfaces.

Mercury is only one example of a toxicant that can produce a hazardous atmosphere in confined spaces that will not be indicated on a typical 4-gas meter or atmospheric monitor. Many rescuers assume that their 4-gas meter will detect all atmospheric conditions that may present a risk to their health or safety, but this is just not true. There are a wide variety of agents or toxicants besides mercury that will not be detected and whose presence may require other controls or the use of respiratory protection. This mistake could be deadly, or leave rescuers with chronic health issues.

In this scenario, for example, if you were an off-site rescuer responding to the above described space in an emergency situation. Without someone on site to inform you of the possible hazard, you would have no indication that any hazards were present. Many times as municipal rescuers we respond to, shall we say, shady locations where unauthorized storage or illegal dumping of hazardous products has taken place; there are no SDS, placards, or signage. Personnel on scene may not know, or may not want to relay vital information about a space of any products within the space.

Rescuers Beware: It's important to play the role of “detective” when planning or preparing to make a confined space entry.

Oftentimes, there are placards or signs on tanks or storage containers to start the investigation into what hazards may be present – and SDS for additional information. However, as rescuers, we often fall into a state of “false security” with our 4-gas meter readings.

While much of our training may include “Go/No Go” scenarios for rescue teams, the use of respiratory protection is usually based on one of the “Big 4” readings on our atmospheric monitors. Unfortunately, this may only serve to reinforce the notion that a 4-gas monitor will always provide the “complete” information of what may be going on inside a confined space. We get dependent on these monitors to tell us if it’s safe to enter without respiratory protection – and there may be much more to the story!

OSHA’s Respiratory Standard [1910.134 (d)(1)(III)] specifies "Where the employer cannot identify or reasonably estimate the employee exposure, the employer shall consider the atmosphere to be IDLH.” 

In the above statement, if you substitute Team Leader for “employer” and “Rescue Team” for employee, you may find that you cannot “identify or reasonably estimate the employee exposure.” Therefore, rescuers would need to use SCBA/SAR and other PPE until you can completely identify what hazards are in the space even though typical monitoring devices are telling us that all is well.

While your standard 4-gas meter is an important screening tool – it is NOT a "catch all" for every atmospheric hazard.

Remember that NIOSH statistics indicate that 40%-60% of confined space entry fatalities are (would-be) rescuers, including both dedicated on-site standby teams and off-site professional rescuers (municipalities) who attempt to perform confined space rescues.

But let’s take this a step further. If you ask most rescuers at what O2 level does an atmosphere become dangerous, they will say below 19.5%. I know from my initial hazmat/confined space training on 4-gas monitors included oxygen displacement. It was so elegantly described to me as “if your monitor shows a decrease in oxygen, it is telling you that something else has pushed out that percentage of oxygen and replaced it with some other agent.” Now, it would be up to you to figure out what else is in the air.

For example, normal breathing air is 20.9%. To get a reading of 19.5% means that about 1.4% of “something else” has displaced the oxygen. Then, depending on what that “something else” is, could require the use of respiratory protection. Hey, wait, the good news keeps coming, and I am getting in way over my head on this science stuff, but my high school chemistry teacher should still be proud. Ambient air is made up of about 79% nitrogen and other gases and 21% oxygen. So, using fingers and toes mathematics, that equals about a 4:1 ratio of nitrogen to oxygen.

In other words, if we have a 1% displacement of oxygen from the breathing air, it will be accompanied by about a 4% displacement of nitrogen (both gases displace at about the same rate). Therefore, instead of it being about a 1.4% percent of an unknown product in our breathing air, it could be as much as 5.6% or more! And, depending on what that product is, it could already be at its IDLH level.

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Project Scientist Spencer Pizzani of Weston Solutions provides this insight.