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Silica is one of the main materials in granite and quartz products and when very fine particles are breathed in, they may lead to adverse health effects. Cutting, grinding and polishing granite and quartz surfacing materials may create small particles of silica with a potential that it may be inhaled by workers. When silica and other dusts get into the lungs our bodies can’t effectively remove it, so it remains in the lungs and can cause scar tissue to form leading to silicosis or lung cancer. Smoking may add also to the damage caused by breathing in silica dust.

OSHA AND SILICA

When there’s a hazard to employees, the federal Occupational Safety and Health Administration (OSHA) isn’t going to be far behind. OSHA has established Permissible Exposure Limits (PEL) in 29 CFR 1926.55 and 1910.1000 not only for silica exposure, but also for marble, limestone and calcium carbonate dust (see Figure 1). It’s highly recommended you hire someone to conduct sampling to measure what your workers are exposed to. There are a number of companies that work as consultants to take samples, analyze the results and make recommendations.

The PEL for marble, limestone, calcium carbonate dusts and most other particles not otherwise regulated (PNOR) is 15 mg/m3 total dust and 5 mg/m3 respirable fraction. OSHA has separated it into two different quantities to differentiate between the sizes of particles inhaled. The total dust is the total amount of material that can be inhaled by the employee and can enter the lungs. The respirable fraction is the amount of material that can be inhaled and will not only get into the lungs, but is small enough to make it down into the alveoli of the lungs, which are the very small sacks where the oxygen is absorbed into the blood stream and wastes gasses are expelled. The body’ filtration system can only handle so much before the system gets overloaded. The farther a particle can travel into the lungs, the harder it will be for your body to get rid of it. OSHA understands this principle and basically says if the smaller particles can get down into the lungs, it could create a greater possibility that the worker may be harmed. OSHA will then establish a lower PEL for that material.

In analyzing silica samples, the sampler and lab will look at the percentage of crystalline silica in the sample and the total and respirable amount of dust present. They then plug that percentage into an OSHA formula, which results in significantly lower numbers. Remember these are the federal OSHA levels and your state may have more stringent levels. Check www.osha.gov or your state government to determine what regulations cover you.

There has been a resurgence in OHSA involvement with Crystalline Silica issues. In January, OHSA announced a National Emphasis Program (NEP) for Crystalline Silica. This allows OSHA to target specific health hazards to employees in certain industries, stonework is one of those industries. As a result, OSHA can conduct targeted inspections and establish outreach programs to help educate employers of the dangers of silica exposure. Fabricators should be familiar with and in compliance with the standards associated with silica exposures because now they are under the microscope.