If there is any question whether confined spaces can be hazardous places, consider the following news item.

In Xinxiang, China, a young woman accidentally dropped her new cell phone into a cesspit when she used the open-pit toilet.
Her husband jumped into the pit to find the phone – worth about the equivalent of $320 in the United States ¬– and lost consciousness.
His mother jumped in to save him, and she, too, lost consciousness.
The woman who dropped the phone then entered the pit, and fainted.
Next, the husband’s father went into the pit and became stuck. Two neighbors who responded to calls for help also jumped into the pit ¬– and fainted.
The husband and his mother died in the hospital. The man’s wife, her father-in-law and a neighbor were also injured in the incident.
According to a newspaper article, eyewitnesses said the victims were all no more than knee-deep in the pit’s contents and for no longer than five minutes (1). 

While there are numerous potential lessons here (including that no piece of equipment is worth risking ones’ life to retrieve from a hazardous confined space), the overarching theme is that confined spaces are often inherently dangerous, and in short, if you’re not properly trained, stay out of them.
Even OSHA has commented on the incident. After examining its records on accident investigations for fatal confined space incidents, the agency concluded that when there were multiple deaths, the majority of the victims in each event died trying to rescue the original entrant from a confined space (2).

This is consistent the National Institute for Occupational Safety and Health (NIOSH) finding that would-be “rescuers” accounted for more than 60 percent of the fatalities in confined spaces.

Some examples of confined spaces in workplace environments are storage tanks, sewers, manholes, tunnels, ship voids, pipelines, silos, wells, pits and trenches. Such spaces require a permit for entry. In fact, in the United States, any pit or trench with a depth equal to or greater than 4 feet is classified as a permit-required confined space.

When determining if an area constitutes a confined space by OSHA definitions, it is always best to err on the side of caution. The experience of Workplace Safety & Health Co., Inc. consultants can be employed to identify confined spaces and assess whether they should be listed as “permit-required.” In some cases, permit-required confined spaces can be reclassified to non-permit spaces if all hazards can be completely eliminated.


Sources
1. http://www.scmp.com/news/china/article/1521835/two-die-cesspit-after-woman-accidentally-drops-her-phone-while-going
2. (https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=PREAMBLES&p_id=839 )