Water Well Journal
Issue link: http://read.dmtmag.com/i/752472
S ilica dust is hazardous when small particles are inhaled. These dust particles can penetrate deep into the lungs and cause disabling—sometimes fatal—lung diseases, including silicosis and lung cancer as well as kidney disease. Silicosis was listed as the underlying or a contributing cause of death on more than 1100 death certificates from 2005 through 2014 in the United States (Centers for Disease Con- trol and Prevention, 2016). Most deaths from silicosis, however, go undiagnosed and unreported. Likewise, the number of silicosis deaths do not include additional deaths from other silica-related diseases such as COPD (chronic obstructive pulmonary disease), lung cancer, and kidney disease. While the number of silicosis cases has declined over the past several decades, more workers died from silicosis in 2014 than in fires or being caught in or crushed by collapsing materials like trench and structure collapses (Bureau of Labor Statistics, 2014). According to the Occupational Safety and Health Adminis- tration, about 2.3 million people in the United States are ex- posed to silica at work. To address occupational exposure to respirable crystalline silica that can be inhaled or breathed in, OSHA has promulgated new silica standards that significantly reduce the amount of silica dust workers can be exposed to on the job. Understanding the major provisions of OSHA's new Silica Rule is the first step towards compliance and protecting the health of workers. What Is Silica? Silica is a compound composed of silicon and oxygen (SiO 2 ) and exists in crystalline and amorphous (having no distinct form or shape) states, both in the natural environment and as produced during manufacturing or other processes. Quartz is the most common form of crystalline silica and accounts for almost 12% by volume of the earth's crust. Quartz accounts for the overwhelming majority of naturally found silica and is present in varying amounts in almost every type of mineral. Thus, quartz is the most prevalent form of crystalline silica found in the workplace. Cristobalite is a relatively rare form of crystalline silica— associated with volcanic activity. Cristobalite can be created during some processes conducted in the workplace. Quartz converts to cristobalite at a temperature around 2700°F. Around 3100°F, cristobalite loses its crystalline structure and becomes an amorphous fused silica. Note that OSHA's new silica standard applies to exposure to respirable crystalline silica, not amorphous silica. Industry Uses There are more than 30 major industries and operations where exposures to crystalline silica can occur. They include diverse workplaces such as foundries, dental laboratories, concrete products, and paint and coating manufacturing. Crys- talline silica exposure also applies to construction activities including drilling, grinding, and using heavy equipment dur- ing demolition activities involving materials containing silica. Exposures to crystalline silica dust occur in common work- place operations involving the following types of operations: • Earth drilling (operations involving disturbance of the earth's crust) • Cutting, sawing, drilling, and crushing concrete, brick, rock, and stone (construction tasks) • Operations using sand products (hydraulic fracturing, glass manufacturing, sandblasting). Sand and gravel are used in road building and concrete construction. Sand with greater than 98% silica is used in the manufacture of glass and ceramics. Silica sand is used to form molds for metal castings in foundries and abrasive blasting operations. Silica is also used as a filler in plastics, rubber, and paint, and as an abrasive in soaps and scouring cleansers. In hydraulic fracturing for oil and gas recovery, silica sand is used to filter impurities from municipal water and sewage treatment plants. It is also used to manufacture artificial stone products used as bathroom and kitchen countertops—where the silica content in those products can exceed 85%. Major Provisions of OSHA's New Silica Rule OSHA promulgated two separate standards that address oc- cupational exposure to respirable crystalline silica. The one applies to exposures in general industry (29 CFR 1910.1053). The other applies to exposures in the construction industry (29 CFR 1926.1153). The two standards are similar with some differences to ac- count for the different work activities, anticipated exposures, and other conditions. The major provisions of OSHA's Silica Rule and the differences between the two standards are sum- marized here. SAFETY MATTERS OSHA'S NEW SILICA RULE Understanding the rule and having a plan can keep workers safe. SAFETY continues on page 42 JEROME E. SPEAR waterwelljournal.com 40 December 2016 WWJ