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Air Quality Issues and Blasting Adapted from Information by the U.S. Dept. of Labor’s Mine Safety and Health Administration When blasting occurs at a mine site, the detonation generates potentially harmful gases. These gases, such as carbon dioxide, carbon monoxide, oxides of nitrogen, ammonia, and sulfur dioxide, contaminate the air; and breathing the contam- inated air may injure or even kill a miner in a few minutes. It is important for miners to know the atmosphere immediately after explosives are detonated may present a health hazard. Since most gases do not have a distinct odor, taste, or color, mine management should consider using instruments to check the oxygen levels and the toxic gas con- centrations in blast areas. Here are a few of the gases all miners should be aware of: Carbon dioxide - After blasting, there is an increase in carbon dioxide which displaces the oxygen in the atmosphere. At lower concentrations, miners respond by breathing faster and deeper (more lung ven- tilation). At elevated levels, carbon dioxide causes inattentiveness, sleepiness, and an accelerated heart rate. This impairment may lead to the potential for increased accidents. Miners with preexisting heart conditions may be severely affected by the elevated heart rate. When the carbon dioxide concentration reaches 3%, the lung ventilation rate doubles; 10% concentration can only be tolerated for a few minutes by a miner at rest. High concentrations of carbon dioxide will asphyxiate a miner. Ammonia - This is a colorless, strongly alkaline gas with a strong irritating odor. As the concentration increases, the penetrating odor becomes increasingly irritating. Ammonia is absorbed by inhalation, ingestion, and probably through the skin at concentrations high enough to cause skin injury. Ammonia irritates the eye and causes tears to form. Additionally, ammonia irritates the mucous membranes in the nose and throat. Mild to moderate exposure can produce headache, salivation, burning of the throat, loss of the sense of smell, perspiration, nausea, vomiting, and chest pain. A rare allergic reaction from inhaling ammonia is hives or nettle rash. Severe exposure can cause death from suffocation or fluid in the lungs (pulmonary edema). Sulfur dioxide - This clear gas has a strong suffocating odor. When inhaled, sulfur dioxide irritates the mucous membranes of the upper respiratory tract. The rapid formation of sulfurous acid on contact with moist mucous membranes explains its prominent bio- logical effect. Chronic effects include dryness of the throat, cough, and inflammation of the mucous membranes in the nose (rhinitis). Acute overexposure may result in death by asphyxiation. Survivors may later develop bronchopneumonia with bronchiolitis obliterans. After an interval of several days, bronchopneumonia may prove fatal in some people. Long-term exposure to sulfur dioxide may result in inflammation of the nasal pas- sages and upper windpipe (nasopharyngi- tis), fatigue, altered sense of smell, chronic bronchitis, as well as shortness of breath, cough, and increased mucous secretion. Carbon monoxide - Carbon monoxide is a dangerous, colorless, odorless, taste- less gas. Known to miners as white damp or the silent killer, it poses a serious health hazard and exposure may even lead to death. When inhaled, carbon monoxide easily enters the blood stream through the lungs. It interferes with the blood's ability to deliver oxygen to the tissues because it at- taches to hemoglobin (the oxygen carrier in the blood). Usually, hemoglobin carries oxy- gen to the tissues. Hemoglobin combines more readily with carbon monoxide than with oxygen; once combined, hemoglobin cannot carry oxygen, causing a lack of oxy- gen in the blood stream despite sufficient oxygen in the ambient air. Therefore, be- cause the blood cannot deliver sufficient oxygen to the tissues, they begin to die. Blasting also reduces the oxygen con- centration in the air which is why it is impor- tant to remember blast areas must be cleared of smoke, dust, and gases before anyone is allowed to enter the area. 33 WorldWide Drilling Resource ® NOVEMBER 2015