Understanding applicable rules and regulations is one of the duties of a safety professional. However, understanding the legal implications of a safety professional's actions and those of an employer is not normally included in the education of a safety professional. This presentation will explain the relationship among statutes, regulations, violations, and civil penalties, with silica as a case study. Significant changes to OSHA regulations, enforcement priorities, rulemaking efforts, and recent court decisions of merit will be reviewed.


Silica is silica dioxide (SiO2). It occurs in both crystalline and non-crystalline forms. Non-crystalline or amorphous forms of silica do not cause occupational disease and generally are not of concern. This is in contrast to crystalline silica.

Crystalline silica is one of the most common minerals in the earth's surface and therefore, it is present in virtually all soils and rocks. Quartz is the most common crystalline form of silica. Crystalline silica is considered respirable, or breathable, when it is present as small airborne particles less than 10 micrometers in diameter. Respirable particles of crystalline silica are common to construction, mining, quarrying, stone operations, foundries, the ceramics industry and cement operations.


Silicosis is a lung disease caused by breathing respirable particles of crystalline silica. It occurs almost exclusively in workers regularly exposed to excessive levels of dust from silica-bearing materials. It is also considered the oldest known occupational lung disease. Writers from Hippocrates (5th Century B.C.) to Ramizzini (18th Century) referred to silicosis. Although it is believed that low levels of respirable silica are present in ambient air, little non-occupational exposure data exists.

EPA reviewed the available data and in a 1996 health assessment found that airborne concentrations below 5 micrograms per cubic meter of air are not expected to be a health concern. EPA concluded that crystalline silica generally does not have the potential to present significant risks to the public.

The term silicosis refers to the scarring caused by the body's reaction to silica particles in the lung. The areas of scarring can be seen on a chest X-ray and are referred to as silicotic nodules. Silicosis is diagnosed through pulmonary function tests, chest x-rays and a history of occupational exposure to silica. The disease has various stages and degrees of severity: chronic, accelerated and acute. The onset and severity of symptoms are related to the intensity of silica exposure. Coughing and breathlessness on exertion are the most common symptoms.

Acute silicosis is a rare form of silicosis disease and occurs after extraordinarily high exposure to silica over a relatively short period of time, such as sandblasting in enclosed spaces without respiratory protection. The symptoms can develop within a few weeks or as long as five years after the exposure. Damage to the lung occurs quickly and is caused by a massive outpouring of protein debris and fluid into the lung. Acute silicosis is treated with steroids, but the prognosis is generally poor.

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