Hazmat 101 News - May 2009

On the 16th of March 2009, at a farm in Warns (a small village in north Netherlands), a twenty-three year old man entered a manure spreader tank to remove an obstruction. He immediately collapsed as a result of hydrogen sulfide poisoning. His father immediately dialed 112 (the emergency telephone number in the Netherlands) and then made a desperate attempt to save his son. As soon as he entered the tank, he too fell unconscious. A neighbor lifted the farmer up with a hook, bringing him closer to fresh air, but he was unable to get him through the narrow entrance of the tank without risking his own life. Firefighters arrived at the scene and got the father and the son out. The son died in the ambulance on the way to hospital. Doctors kept the father asleep for two days to give his stricken brain time to recover. He was able to attend the funeral of his son. He managed to do that on foot, which was a miracle on itself, as some victims with severe hydrogen sulfide poisoning spend the rest of their lives in a wheelchair or even live in a vegetative state.

Hydrogen sulfide is a dangerous gas. In very low concentrations, starting at about 0.005 ppm, most humans can detect its characteristic odor, described as resembling "a rotten egg." At a concentration of 100 ppm, the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, together with awareness of danger. At several hundreds of ppm, the gas is deadly within minutes. At a concentration above 1,000 ppm, one breath of the gas is enough to make a healthy person fall down unconscious.

The media mistakenly often blame ammonia or methane as the cause of death in manure-related accidents. Ammonia, however, is released in much lower concentrations than hydrogen sulfide (depending on the acidity of the manure), and it is also much less deadly than hydrogen sulfide. Moreover, unlike hydrogen sulfide, it is lighter than air, making it dissipate within seconds. Methane can be released at high concentrations (not ppm but percentages in air). It can cause death by displacing oxygen--for which you need a lot--or through fire or explosion--which requires an ignition source.

Jetty after measuring the H2S concentration in foaming manure and having determined it to be safe. It is important to wear breathing apparatus when you take measurements.

Why did I write this article for emergency responders? Not because hydrogen sulfide can be released from manure pits or silos. Fire departments in rural areas already know about this risk and firefighters in urban areas will not likely encounter manure. However, hydrogen sulfide can also be produced in places where it is least expected. As a result, people, including emergency responders, can be taken by surprise.

Hydrogen sulfide can be produced at any location where biological or organic material breaks down in the absence of oxygen. At biogas installations, in crude oil, gas wells, compost, septic tanks, sewers and waste water treatment plants.

On 31 March 2009, 10,000 cubic meters of biogas escaped from the new water treatment plant in Amsterdam West. The environmental service blamed the company for the fire and explosion risk caused by the escaped methane. Luckily, no one got hurt in this incident, but it might have ended very differently, as proved the incident on a Canadian mushroom farm on 5 September 2008. Here, three men died and three got critically injured when a biogas pipeline ruptured inside the building where some of them were working. The men who worked inside died immediately. Others who ran to their rescue were reportedly in critical condition. Hydrogen sulfide was the cause.

Accidents in which hydrogen sulfide is involved happen much more often than most people think. Most of them take place in silence. People do not speak about them, mostly out of shame, especially when only animals are victims, or if a human victim quickly recovers in fresh air. Most people involved know the risks, but do not always take them seriously.

Recently another type of hydrogen sulfide incident has become more and more common in Japan but has now also emerged in the USA. Hydrogen sulfide suicide. The suicide candidate locks him- or herself up in a small room (bathroom, toilet, car) and then mixes two chemicals, leading to the uncontrolled release of hydrogen sulfide. If the suicide candidate does it "neatly", the door or a window has a warning sign on it so that potential rescuers are warned. If not, the vicinity will often notice it by the protruding stench and relatives or emergency workers fall ill or even die in an attempt to save the victim. Many people have ended in hospital because the hydrogen sulfide spread through the ventilation system.

Incident procedure
Because the chance for firefighters to encounter a hydrogen sulfide incident seems likely, it is wise to check the incident area for the presence of hydrogen sulfide. Although Draeger tubes can be used, a better choice is the use four cell meters to measure flammable gas, oxygen, carbon monoxide, and hydrogen sulfide because these instruments can provide continuous readings.

Mixer ready to start mixing manure

As hydrogen sulfide is a poisonous gas, an incident with this gas automatically is a hazmat incident. However, rescuers do not need to wear hazmat suits. Normal firefighter gear with a breathing apparatus is adequate. It is very important to use the right method of decontamination afterwards. Decontamination with water with or without detergent is useless, as the gas does not react with skin moisture and remains in the clothes when these are flushed from the outside. The right way to decontaminate is by ventilation! The breathing apparatus needs to be kept on while blowing high volume of air into and onto the clothes. During the decontamination, the clothes need to be kept open or pulled out, which is a challenge while keeping the breathing apparatus on, but it is really necessary. The clothes need to be checked for traces of the gas before the ventilation is stopped. If a firefighter takes off is breathing apparatus too soon, he may get intoxicated, too. This happened to a group of experienced firefighters in Rhadereistedt, Germany on 8 November 2005. After they removed four hydrogen sulfide victims out of a biogas building, gas fumes escaping from their clothes made them fall ill. The four rescued victims died. Two of them were declared dead on the spot, the other two later died in hospital. A fifth victim survived the ordeal. He had entered the building after the hydrogen sulfide cloud had escaped from a waste silo. He barely managed to get out of the building himself and had collapsed after having warned the emergency services. For a while his life was in danger too.

I want to end with a request. Last year, I started an accident register on manure gas accidents which have lead to either sick or dead people and livestock or to explosions and/or fire because of ignition of manure gasses. The registered accidents are only the tip of the manure gas ice berg. Often when I give lectures on this subject in rural areas and ask local volunteer fire fighters who are also farmers, if they personally have any experience with manure gas incidents, they deny this, but their eyes tell a different story. I hope that readers of this article who know of such incidents, are willing to report them to me with as many details as possible (date, place, description of what happened, any measurement info available, amount and state of the victims, both human and animals). Privacy related info like the victim's names is not relevant for my register. And of course anyone who is interested in my register can ask for a copy.

Hazmat 101 News - May 2009

Emergency Responders Beware: Hydrogen Sulfide is Deadly--When its Smell Disappears, the Danger is Biggest!