A hazardous atmosphere in a permit-required confined space is an atmosphere that may expose employees to the risk of death, incapacitation, and impairment of ability to self-rescue, serious injury or acute illness due to:
- An Atmospheric concentration of oxygen that is less than 19.5%
- Flammable gases, vapors or mists in excess of 10% of their LFL within the environment
- an airborne combustible dust at a concentration of oxygen above 23.5%
- An airborne concentration of a substance that exceeds the dose or exposure limit specified by an OSHA requirement
- Any other atmospheric condition recognized as immediately dangerous to life or health
Case Study (Flammable Gas Explosion)
Engulfment by Material
As defined by OSHA in 1910.146(b), engulfment means the surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system or that can exert enough force on the body to cause death by strangulation, constriction, or crushing.
- Solid Material:
Engulfment in loose, granular materials is a very common type of confined spaze hazard that can turn a confined space into one that is permit required. Perhaps the most common situation that occurs deals with scenarios where some type of material (grain, sawdust, sand, coal etc) is being unloaded from a silo, bin, hopper or tanks and becomes lodged, requiring work by the person unloading to attempt to restart the flow of materials. In its study , "Worker Deaths in Confined Spaces" NIOSH describes a number of different scenarios where workers were unloading loose materials that suddenly stopped flowing, causing the person, often a solitary worker, to attempt to remedy the issue by climbing into the object that was being unloaded only to be engulfed when the materials ultimately became dislodged due to their weight or their prodding once inside.
Similar situations have also been known to occur where a victim has entered a confined space where a liquid is present and one of two scenarios plays out. Either the person is initially overcome by the atmosphere, passing out and becoming submerged within the liquid inside, or a mistake is made during the work process that allows the quick entry of a liquid into the space, not allowing the worker to escape in time.
Internal Configuration is the simple design of the space with inwardly converging walls. Here, the issue is not always that the worker becomes trapped in any material (although it is commonly tied in to the incident), but rather that the worker enters a space where walking is difficult due to sloping walls which converge in such a manner that a real potential exists for the worker to slide downward into a tight space from which they are unable to extricate themselves.
This problem is often compounded by the type of work that is being completed, such as painting or cleaning with a slick material that causes the worker to initially slide downward to a point where they simply become stuck. The problem then becomes exacerbated as they attempt to free themselves, instead only becoming more firmly wedged inside to the point where escape becomes impossible and breathing limited due to the tight constriction of the space on the body. Often, the potential here is suffocation as the worker slowly loses strength and becomes less able to breathe due to the tight spot.
Outside of confined spaces, falls represent the number one cause of death on construction sites and for many years in the early to mid parts of the beginning of the 21st century the second leading cause overall in all of industry, behind only automobile incidents. Thus, when coupled with a confined space hazard, the risks of a fall cannot be overestimated.
- Same Level Falls
- Falls to a Lower Level
Case Study: Fall Hazard
The potential for objects to be dropped from above must always be considered when working in any location, including inside confined spaces. Because of the tight confines and access hatches in vertical entries, tools can be dropped that strike the unaware worker below, causing major injury.
According to “A Guide to Safety in Confined Spaces,” “Noise problems are usually intensified in confined spaces because the interior tends to cause sound to reverberate and, thus, expose the worker to higher sound levels than those found in an open environment. This intensified noise increases the risk of hearing damage to workers, which could result in temporary or permanent loss of hearing. Noise in a confined space that may not be intense enough to cause hearing damage may still disrupt verbal communication with the emergency standby person on the exterior of the confined space. If the workers inside are not able to hear commands or danger signals due to excessive noise, the probability of severe accidents can increase.”
Although the potential for electrical hazards exists elsewhere outside of confined spaces, the fact that these locations often restrict the worker’s ability to stay away from the hazard and the general conditions, which are often dark and damp, lead to the risk of the worker making contact with an exposed electrical wire and providing a relatively unimpeded path to ground through their body, leading to such possibilities as heart and breathing stoppage as well as severe burns due to the inability to let go of the exposed conductor.
Incidents that occur due to electrical hazards often involve such things as:
- Exposed energized electrical parts (on electrical tools being used or on fixed equipment inside the space)
- Open lighting parts (such as broken light bulbs or exposed conductors for light bulbs that have not been installed);
- Damaged insulation on power cords
In some cases, accidental contact is made in a situation where the worker is not an electrician and is unaware of the hazards in the area in which they work. In others, electricians themselves have died because of cutting corners. For example, NIOSH details a case in an underground transformer vault where a sump pump failed but the electricity was never turned off to it, thus resulting in an electrically charged hip-deep water hazard for the victim. And although he was initially protected while wearing rubber hip waiters into the space, he accidently made contact between a metal part which had become energized due to the risen water level in the space and another metal component, giving the electricity a path through him to ground. Then, as rescuers attempted to perform a rescue, each one noted as they entered the water without protection (rubber hip waiters), an electrical shock, resulting in their retreat and a delayed rescue attempt. In another situation, the victim failed to use an amp probe to test whether or not the conductors that he was working on were live, thus making contact when he cut through a circuit conductor to make a splice.
Changing the workplace to eliminate the hazard. Ex. putting the lights in a crane bay on hoists so that the lights can be lowered and changed at ground level versus having to climb or use a lift to get to the lights. Another example would be substituting a toxic solvent with a non-toxic solvent therefore eliminating the hazard.
Physically changing the space to control a hazard. An example would be to add a ventilation hood at the point of exposure to welding fumes so that worker exposure is reduced and the overall work area exposure is reduced. Also a guard rail installed protecting workers in a fall hazardous area from exposure to a fall hazard would be another example.
Restricting access or implementing a procedure to reduce the employee exposure to a hazard. Restricting access to a crane ladder would only allow workers trained and authorized to access the hazardous area. Increasing the frequency of breaks and hydration for workers in a hot work area to reduce the chance of heat related incidents would also be a form of administrative controls.
When the higher order safety controls are not able to be used then the worker must be protected from the hazards in the work area by wearing protective equipment as protection from the work are hazards.