• Silos like these present hazardous confined spaces at some workplaces.silo image by Jorge Chaves from Fotolia.com
  
  Many industrial facilities have what OSHA defines as "confined spaces" on site. These spaces, like vats or storage containers, present specific hazards and may have to be entered by employees to do work. If employees are careless, confined space entry by an untrained person can result in serious injury or death. That's why OSHA has specific standards for confined spaces and workers who enter them.
  
  

Definition

• OSHA regulation 29CFR 1910.146 defines a confined space as a place that is "(1) Large enough and so configured that an employee can bodily enter and perform assigned work; and (2) Has limited means for entry and exit (for example tanks, vessels, silos, storage bins, hoppers, vaults and pits are spaces that may have limited means of entry.); and (3) Is not designed for continuous occupancy." For these confined spaces, OSHA requires they be entry by permit only. OSHA differentiates between permit-required confined spaces and non-permit-required confined spaces. Non-permit confined spaces are those that do not contain or "with the respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious physical harm."
  
  

Hazards

• Because they are confined, these spaces present certain atmospheric hazards. For example, a storage bin with poor ventilation might present the danger of a low oxygen atmosphere. Certain chemicals may leave vaporous residue which can be harmful to employees and silos present the possibility of engulfment. Some chemicals or processes that take place in storage bins may actually produce oxygen, resulting in an oxygen-enriched environment. Such an environment is volatile and is a dangerous place for welding or any operation which may cause sparks.
  
  

Precautions

• To protect workers in these situations, OSHA requires confined spaces be entered only by properly trained personnel and rescue personnel be available. Some facilities have their own on-site confined rescue teams. These facilities are often located in rural areas where fire and EMS departments lack the skills and equipment necessary to deal with confined space rescues and response times are inadequate. The precautions OSHA requires for confined space entry are that there must be a permit system in place and there must be an attendant present whenever someone enters a confined space to do work. The permit is an internal document created by the company. The permit will note who is going to enter what, how long the entry will take and what work is to be done.
  
  

Attendants

• OSHA requires that any time someone enters a permit-required confined space, an attendant must be present. The attendant, sometimes called a "hole watch," does not enter the space himself, but is there to monitor conditions in the confined space and to intervene in the event of an emergency. The attendant's job is to monitor the confined space's atmosphere, usually with an oxygen meter. The attendant will notify the entrant(s) if atmospheric readings are not at desirable levels and all entrants must exit the confined space. Furthermore, the attendant must have ready access to a two-way radio, telephone or other means of calling for help in case of emergency. The attendant may not enter the confined space, but may perform a non-entry rescue such as using an entrant's retrieval line to remove him or her from the space.