Silica

Silica in Indiana Silica Sand (primarily Quartz) Cement Limestone Gypsum Road & farm dust Breathing is a process of inhaling and exhaling that allows oxygen and carbon dioxide to be exchanged. When we breathe, we not only take air into our lungs, but also small, nearly microscopic particles. Most of these particles will be exhaled or removed in other ways (coughing, sneezing, mucus, etc.). However, a small fraction of these particles will remain in the body. What stays is determined by the size of the particle. That’s right, when it comes to respirable hazards (dust, silica, dpm) size does matter.

Silica Content Limestone ½ -20% Sandstone 50-100% Granite 20-70% Shale 5-20% Slate 15-40% Most of the rock mined by Rogers has very low percentages of silica, usually falling between 1 - 10%, however in places like Arkansas silica content can be as high as 80 - 90%.

Limestone & Sand MSHA Sampling has found up to 20% Average of .5 - 5% crystalline silica Highest in east, lowest toward west & south Breathing is a process of inhaling and exhaling that allows oxygen and carbon dioxide to be exchanged. When we breathe, we not only take air into our lungs, but also small, nearly microscopic particles. Most of these particles will be exhaled or removed in other ways (coughing, sneezing, mucus, etc.). However, a small fraction of these particles will remain in the body. What stays is determined by the size of the particle. That’s right, when it comes to respirable hazards (dust, silica, dpm) size does matter.

Dust Sources Quarry – drilling, blasting, hauling Plant – conveyors, crushers, screens Stockpiles Roads Breathing is a process of inhaling and exhaling that allows oxygen and carbon dioxide to be exchanged. When we breathe, we not only take air into our lungs, but also small, nearly microscopic particles. Most of these particles will be exhaled or removed in other ways (coughing, sneezing, mucus, etc.). However, a small fraction of these particles will remain in the body. What stays is determined by the size of the particle. That’s right, when it comes to respirable hazards (dust, silica, dpm) size does matter.

Respirable Dust Less than 10 microns in diameter What’s a micron 1/24,000th of inch Human hair 40-150 microns in diameter In order for dust to be hazardous to our health, it must be very small, less than 10 microns in diameter. A micron is very small indeed, 1/24,000th of an inch. To give you a reference, a human hair is 40 - 150 microns in diameter. To give you a better idea, look at this next picture.

Breathing Inhale/exhale Oxygen/CO2 exchange Air & particulates Breathing is a process of inhaling and exhaling that allows oxygen and carbon dioxide to be exchanged. When we breathe, we not only take air into our lungs, but also small, nearly microscopic particles. Most of these particles will be exhaled or removed in other ways (coughing, sneezing, mucus, etc.). However, a small fraction of these particles will remain in the body. What stays is determined by the size of the particle. That’s right, when it comes to respirable hazards (dust, silica, dpm) size does matter.

Breathing Small fraction of inhaled particles are deposited Remainder exhaled or removed Size determines what stays Breathing is a process of inhaling and exhaling that allows oxygen and carbon dioxide to be exchanged. When we breathe, we not only take air into our lungs, but also small, nearly microscopic particles. Most of these particles will be exhaled or removed in other ways (coughing, sneezing, mucus, etc.). However, a small fraction of these particles will remain in the body. What stays is determined by the size of the particle. That’s right, when it comes to respirable hazards (dust, silica, dpm) size does matter.

Mucociliary Escalator Covered with cilia Hair-like Lash back & forth Move trapped particles up Swallow or spit The mucus in our windpipe and lungs surrounds the tiny particles. Coating them and lubricating them, making them easier for the cilia to move. Cilia are tiny hair like particles that are constantly moving, forcing the dust particles back up our respiratory system…toward our mouths. An easy way to imagine this is to picture an escalator, its steps always moving up. Transporting our unwanted “guests” back out of our body. When the mucus covered dust reaches our mouths, we remove it by either swallowing it or spitting it out.

Cilia

Respiratory System Gas Exchange Supply Oxygen Remove Carbon Dioxide Nose or Mouth Windpipe Mucous & Cilia Alveolar Region To better understand why dust is harmful to our health we need a basic understanding of how our respiratory system works. The purpose of our respiratory system is supply our body with needed oxygen and to rid our body of harmful carbon dioxide. The four main parts of our body used in this process are our nose, mouth, windpipe, and lungs. All of these have defense systems built in to keep unwanted particles from damaging our lungs. Our noses are filled with tiny hairs and mucus that capture larger dust particles and prevent them from entering our windpipes. Our windpipe and lungs contain mucus and cilia to capture smaller dust particles that get past our mouths and noses.

Bronchial Tree Tree branches Divided into smaller & smaller branches Bronchioles When our windpipe reaches our lungs, it divides into two tubes one entering each lung. These tubes continue dividing and branching into smaller tubes that resemble the branches of a tree.

Branch At the end of each bronchial tube are a cluster of alveoli. This is where oxygen/carbon dioxide exchange occurs..

Business End of Lungs Alveolar clusters & sacs 150-400 microns in diameter - These tiny clusters are truly the business end of our lungs. Everything else simply guides the air we breathe here and acts as a defense to keep harmful substances from reaching this point. - If harmful particles, such as silica, get to this point they can block oxygen/carbon dioxide exchange points.

Business End of Lungs Walls contain capillaries Oxygen/CO exchange - These tiny clusters are truly the business end of our lungs. Everything else simply guides the air we breathe here and acts as a defense to keep harmful substances from reaching this point. - If harmful particles, such as silica, get to this point they can block oxygen/carbon dioxide exchange points.

Fate of Dust Macrophage cells Act like Pacmen Engulf dust - But, our bodies aren’t ready to give up just yet, we have yet another defense. Macrophage cells. These cells surround small particles of respirable dust that make it past the mucus membranes and the cilia. The trapped particles are then transported to nearby lymph glands. Silica is surrounded by these cells but cannot dissolve them and the cells are destroyed and leave scar tissue which will not function to exchange oxygen.

3 Types of Silicosis Chronic Accelerated Acute - Unfortunately, macrophages are built to attack bacteria and the silica that they engulf kills the cell. As the dead cells accumulate they form large knots of scar tissue. Which then limit the lungs’ ability to stretch, limiting the amount of air that can be breathed in. - This condition is known as silicosis. The most common form of silicosis is Chronic. Chronic silicosis develops after years of being exposed to silica levels above the Permissible Exposure Levels established by Regulatory Agencies. - The signs and symptoms of silicosis include frequent dry coughs, shortness of breath, wheezing, and increased fatigue. These symptoms become worse as the disease progresses. -There is no cure and no effective treatment for silicosis and so the only alternative is prevention. - The silver lining to this very serious cloud is that the disease rarely occurs in people whose occupational exposure is below the established Permissible Exposure Levels.

Smoking Compounds respiratory problems Paralyzes cilia “Reduced ability of the lungs to work properly - a process accelerated by smoking - increases the risk of death from all causes.” University Science News 8/22/01 Most of us know that smoking is bad for us and few of us are surprised that smoking is linked to lung cancer and many long-term lung diseases such as emphysema and bronchitis. While smoking does not increase the frequency of silicosis cases, it does damage air ways and lung function which can make the symptoms of silicosis more severe. One of our bodies best defenses against foreign particles like silica are the cilia that line our windpipe and move the particles back up and out of the respiratory system. Smoking paralyzes the cilia and compromises this defense…allowing more and larger particles to enter our lungs.