By O. A. Ileperuma
The recent disaster at a gem pit in Kuruvita brings to light those occupational hazards which can be fatal o workers involved in gem mining. In this incident five gem miners died of gas poisoning and several years back three people died when they were trying to clean the bootom of a deep water well at Piliyandala. Other disasters where people have succumbed to gas poisoning trying to clean drinking water wells have been documented.

It is important for the general public to understand the reasons for this type of deaths and get educated to advise people who will undertake similar jobs in the future. In the most recent disaster at Kuruvita, carbon monoxide emitted during the burning of kerosene used as fuel for the water pump has been blamed for these deaths. Carbon monoxide is a colourless gas with no smell but highly poisonous. It binds with haemoglobin in blood thereby depriving the body of vital oxygen necessary for normal body functions. There is a natural concentration of carbon monoxide in the range of 1-5 parts per million (ppm) in the atmosphere and at this level it does not adversely affect the human body. Higher levels of carbon monoxide are encountered inside motor cars caught up in traffic jams or those who are continuously exposed to fumes from motor vehicles. At these elevated carbon monoxide levels the symptoms experienced are headaches and nausea. Exposure to a 30 ppm concentration for about 8 hours is sufficient to cause these symptoms. If the concentration of carbon monoxide in the air we breathe reaches around 1%, then 90% of our body haemoglobin is rendered useless for carrying oxygen and severe malfunctions of the body is the result. There will be initially a general inactivity of the body which is followed by death if immediate medical attention is not available. A water pump operating deep inside a gem pit can produce these high levels of carbon monoxide enough to kill a normal healthy person.

People in the west are more accustomed to these dangers through their experiences with coal mines. During the early days of coal mining miners used to take a caged bird by the name canary ahead of them inside the mine. If the bird drops dead the miners immediately would return to the surface since the air inside the mine is not conducive for people to stay and work. The coal mines today are continuously fed with air from the top through large tubes with venting open to the underground areas. In a deep mine there can be high concentrations of carbon dioxide since it is heavier than most components of air such as nitrogen and oxygen. Methane coming from the decomposition of organic matter is another major component of underground mines. Methane itself is inert and non-toxic but we should realise that only oxygen supports respiration. As such, even if the gases are non-toxic people die of suffocation when exposed to such polluted air. As a result of high concentrations of these gases, miners working underground are deprived of fresh air to breathe. The supply of fresh air is meant to alleviate this danger. The possible cause of death of these people who go inside deep wells is most likely to be due to the deprivation of oxygen in the air they have to breathe. In addition , there is also an appreciable amount of methane inside a well or a gem pit. This gas is produced by certain types of bacteria acting on organic matter such as rotting leaves in a well.

Although methane is non-toxic, other gases such as hydrogen sulphide which is extremely poisonous are also present inside a deep water well and in gem pits.. This gas has a very characteristic smell of that of rotting eggs and is responsible for the foul smell emanating from coconut husk pits commonly found along the coastal line towns. However, this smell can be experienced only at very low concentrations (those in the parts per billion range). When the concentration reaches parts per million range, people will not smell it as it numbs the olfactory nerves and hence we do not smell it at higher levels. People start to show signs of poisoning at this stage and most countries have legal limits of exposure to hydrogen sulphide. Thus in the USA, at the 15 parts per million level the law limits exposure of a worker to 15 minutes per day. At a few thousand ppm concentration, a person will die on contact with the gas as the nerves around the heart and lungs get paralysed.. Hydrogen sulphide should be thought of similar to cyanide with respect of its poisoning ability. All these gases are produced more effectively under water logged conditions. Hydrogen sulphide gas can kill a person if exposed for a sufficient period of time even if oxygen is present at an appreciable level.

How then are we to address this problem and prevent such disasters happening in the future ? It is important for the general public to be aware of the potential dangers of working underground. In cleaning wells, specially deep ones, workmen should not be inside a well for a long time but should come to the top periodically to breath fresh air. A more professional approach of course would be to use oxygen tanks. In the case of deep gem mines, air should be pumped in order for the miners to receive fresh air continuously form the surface. There are portable monitors available to monitor the levels of methane, carbon monoxide and hydrogen sulphide. In other countries, these are regularly used to monitor the levels of gases in underground mines and other workplaces susceptible to this type of poisoning. The gem corporation has a moral obligation to educate the miners on the potential disasters of working underground and take some action to monitor the air quality in underground mines so that incidents such as what happened Kuruvita need not be repeated.