The use of silica sand as a blasting media is banned in many country’s around the world, prominently Australia. Unfortunatly for the un-suspecting blasters silica sand is still sometimes used in the United States of America. A large number of research and hazard studies have been conducted that show the dangers and health implications of using silica sand.
For normal abrasive blasting it is never safe, not even when you are wearing an approved respirator. The only exception maybe in a fully contained blast and vacuum system where all possible precautions have been taken to minimise any possibe chance of exposure to personnel.
Blasting with silica sands, such as beach sand, river sand, and any other crystalline silica sand may cause serious injury or be fatal. Crystalline silica is recognized world-wide as a Class 1 Carcinogen. The silica sand type abrasive media when used in abrasive blasting, typically fractures into fine particles and becomes airborne. When workers inhale the crystalline silica, the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles [Silicosis and Silicate Disease Committee 1988]. This fibrotic condition of the lung is called silicosis.
Types of silicosis
A worker may develop any of three types of silicosis, depending on the airborne concentration of crystalline silica.
Typically occurs after 10 or more years of exposure to crystalline silica at relatively low concentrations.
Results from exposure to high concentrations of crystalline silica and develops 5 to 10 years after the initial exposure.
Where exposure concentrations to silica sand particles are the highest and can cause symptoms to develop within a few weeks to 4 or 5 years after the initial exposure [Peters 1986; Ziskind et al. 1976].
Silicosis, especially the acute form, is characterized by shortness of breath, fever, and cyanosis (bluish skin); it may often be misdiagnosed as pulmonary oedema (fluid in the lungs), pneumonia, or tuberculosis. When a contined use of silica sand as a blasting media, the life expectancy of blasting operators and other exposed personnel is reduced by one day for every day of exposure.
There are documented cases where blasting operators and other personnel families have been inadvertently exposed to silica dust after comming into contact with contaminated clothing and other objects. Blasting operators offten believe that due to the fact that they wear a blast helmet while blasting it will prevent them from exposure and keeps them safe. However, dust particles lying around after blasting can be swept up by the wind, distrubed during clean-up after blasting and present just as much of a danger as when blasting was taking place.
A lot of people have asked what is the difference between lying on the beach and being exposed to this silica sand? The answer is quite simple – in a blasting application the silica sand is blasted at 400mph and pulverized into dust which makes its way into your lungs and breathing passages.
Many health departments state that if silica sand is to be used, the blast room should be completely swept clean before the door is opened, to stop dust entering other workplaces. Any workers in the vicinity should also wear supplied air respirators and all blasters should shower and leave contaminated clothing at the workplace [Centers for Disease Control and Prevention].
The current OSHA permissible exposure limit (PEL) for respirable dust containing crystalline silica (quartz) for the industry is measured by millions of particles per cubic foot (mppcf). The NIOSH 1974 recommended exposure limit (REL) for respirable crystalline silica is 0.05 mg/m3 as a TWA for up to 10 hours/day during a 40-hour workweek.
Crystalline silica inhaled in the form of quartz or cristobalite from occupational sources is carcinogenic (cancer causing) to humans (Group 1).
-The International Agency for Research on Cancer, Silicosis: a slow death
… the most severe worker exposures to crystalline silica results from sandblasting.
-The U.S. Department of Labor, Occupational Safety & Health Administration
… the use of crystalline silica was banned for most blast-cleaning operations in Great Britain in 1950 (Factories Act of 1949) and in other European countries in 1966. In 1974, NIOSH recommended that silica sand be prohibited for use as an abrasive blasting material and that less hazardous materials be substituted for silica sand during abrasive blasting.
-National Institute for Occupational Safety and Health(NIOSH)
California, Louisiana, Ohio, Utah, the Port of Houston, and the U.S. Navy have banned sandblast products with more than 1% silica.