Suffocation Hazards in Confined Spaces

KOSHA signals warning and stresses 3 safety tips

May 31, 2011

In preparation for the summer season, the warning signals are up for operations in confined spaces such as manholes, water-purifier tanks, etc.

On May 26, a worker collapsed due to suffocation as he was entering inside a sewerage through a manhole, at a sewer system repair site in Busan. A co-worker of the collapsed worker also entered the sewerage in rescue and was suffocated as well. This accident led to a fatality and the other worker is in critical condition.

High temperature and localized heavy rains in summer, lead to the proliferation of micro-organisms thus raising the risks of accidents involving suffocations caused by oxygen deficiency.

Statistics on suffocations accidents at work show 37 fatalities in the past three years, and 48% of the deaths ? 18 deaths ? occurred from June to August.

* Suffocation accidents at work from 2008 to 2010                                                                   (unit: No. of persons)

* Monthly suffocation accidents at work from 2008 to 2010                                                  (unit: No. of persons)

The worksites where the most number of suffocation accidents occur are waste water treatment facilities with 12 deaths, followed by manholes (9 deaths), and storage tanks and chemical facilities (8 deaths).

* Suffocations accidents by worksite types from 2008 to 2010                                             (unit: No. of persons)

Confined spaces like waste water treatment facilities, manholes, and water-purifier tanks have limited access of humans and are poor ventilated. Since these confined spaces easily run out of oxygen and build up toxic gases like hydrogen sulfide, there are high risks of accidents.

Entering or working in confined spaces without the aid of ventilation or protective equipment can cause oxygen deficiency or the exposure to toxic gases leading to symptoms like unconsciousness, convulsions, and even deaths in extreme cases. Confined spaces with less than 10% of oxygen concentration can render a person unconscious upon entering the space and kill him within minutes.

Against the backdrop, Korea Occupational Safety and Health Agency (KOSHA; President: Min-Ki Noh) designated the months June through August as the emphasis period for preventing suffocation accidents in industrial sites. While raising the alarm against hazards, KOSHA set out “Three safety tips for work in confined spaces” to check workplaces’ compliances with the guidelines and extend technical support.

Three safety tips for work in confined spaces are:

Measuring oxygen and toxic gas concentrations before and during work

Ventilating confined spaces before and during work

Wearing protective equipment when conducting rescue works in confined spaces

In addition to following the tips above, it is necessary to take additional safety measures including the placement of an observer, checking the numbers of workers, and preparing safety devices.

In addition, KOSHA leases oxygen indicators, air masks, portable ventilation fans and so on to workplaces, free of charge, upon their requests. Also, if workplaces wish to purchase these devices, KOSHA provides financial assistance of 50~80% of the prices.

Further information about the lease or purchase of safety devices is available from the website at http://www.kosha.or.kr/.

“According to the weather forecast, we will experience more frequent rains and high temperature this summer. This gives us the reason to pay more attention to suffocation hazards in confined spaces,” said Director Jungsun Park of Occupational Health Department, calling for the observance of Three safety tips for work in confined spaces.

- Examples of suffocation accidents in confined spaces in 2010 -

Case #1

On September 19, 2010 in a waste water treatment tank located at an underground parking lot in Ulsan, a worker cleaning the tank collapsed due to toxic gas poisoning (hydrogen sulfide). Two other workers who went inside the tank to rescue the first worker were also poisoned by the toxic gas. All of the three workers died.

Case #2

On August 20, 2010 a worker was removing waste water inside a treatment tank. The treatment tank was being dismantled and was located in an apartment complex in Yongin, Gyeonggi-do. The worker collapsed due to hydrogen sulfide poisoning, and other four workers who had been working nearby went inside the tank in rescue. The workers succumbed to the toxic gas one by one. One of the workers died and four others fell into critical conditions.