Silica Dust in the Construction Industry:

A Guide to Respirable Crystalline Silica and the OSHA PEL

About Silica Dust

  • Chemical Formula SiO₂
  • Silica is Quartz, and is found naturally in almost all rock, sand, soil, brick and concrete products
  • Respirable crystalline silica particles penetrate deep into the lungs causing lung disease
  • OSHA, after decades of scientific studies on respirable crystalline silica, adopted its first PEL in 1971
  • Silica exposure remains a serious threat to nearly 2 million U.S. workers, including more than 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stone cutting, rock drilling, quarry work and tunneling
Silica Particles

Silica Health Effects

Symptoms of Inhaled Silica

  • Shortness of breath
  • Loss of appetite
  • Chest pains
  • Fatigue
  • Severe cough
  • Cyanosis (bluish skin)

Silicosis: A non-reversible lung disease.

  • Acute silicosis: cough, weight loss, and fatigue presents in a few weeks or years of exposure to inhaled silica.
  • Chronic Silicosis: appears 10 to 30years after exposure, afects upperlungs and causes extensive scarring.
  • Accelerated Silicosis: occurs within10 years of high-level exposure.

Chronic obstructive pulmonary disease (COPD)

  • COPD causes obstructed airflowfrom the lungs. Airways become thick and inflamed and air sacs lose their elastic quality. Too much mucus is made and blocks airways.

How Does Silica Get Into The Lungs?

 
 

Silica Exposure in Common Construction Work Practices

What kind of work practices cause silica exposure? Below are many common work practices used today in the construction industry that create silica exposure.

  • Cutting Ceramic and Porcelain Tile
  • Cutting Concrete
  • Cutting Clay Brick
  • Cutting Concrete Pavers
  • Cutting Concrete Masonry Units (Block)
  • Cutting Natural Stone
  • Cutting Clay and Concrete Roof Tile
  • Cutting Asphalt

Each of these work practices can potentially expose workers to respirable crystalline silica at levels 10X to 200X above the OSHA PEL.

Download the iQ Air Sampling White Paper

The OSHA PEL Explained

What Contractors Need to Know About the OSHA PEL

Silica is an important topic in the construction industry with the new rule passed by OSHA, which reduced the permissible exposure limit (PEL) to 50 micrograms of respirable crystalline silica per cubic meter of air (μg/m3), averaged over an 8-hour day.

The new rule requires employers to use engineering controls to limit worker exposure, develop a written exposure control plan, and train workers on silica risks, among other requirements.

The new OSHA PEL was approved in 2016, with employers in the construction industry required to comply by June 23, 2017.

What does all this mean to the average contractor? We’ve created this silica dust resource page for contractors and industry professionals to help answer that question.

Using this page you’ll:

1) Understand OSHA PEL in simple terms
2) Know how to inexpensively test your silica exposure
3) Understand your options for controlling silica dust

What is the OSHA PEL?

‘Permissible Exposure Limit’ is the legal limit established by OSHA for worker exposure to silica. In simple terms, how much dust a worker is legally allowed to breath over an eight hour period.

The PEL is determined by three factors: Air, Dust and Time. For us to understand the PEL we need to have a better grasp of each factor.

 

AIR

The first factor in the OSHA PEL

Air Intake Factors

The first factor in calculating the PEL is air. How much air does a person breathe? The answer depends on a number of factors.

  • Height
  • Weight
  • Fitness level
  • Activity

For the construction industry we’re going to make an assumption that the average adult male employee works at a moderate activity level.

Looking at this chart, we’ll use 35 liters per minute, an activity level right between a brisk walk and mowing the lawn.

1 min = 35 liters

The Math

As a visual reference, Joel is standing in the middle of a 16.8-meter cube that represents the quantity of air inhaled in during an 8 hour workday.

1 min = 35 liters

1 hour = 2100 liters

2100 liters/hour x 8 hours = 16,800 liters per day

Or 16,800 liters ÷ 1000 liters = 16.8 m3

The average adult male working at a moderate activity level inhales 16.8 cubic meters of air over the course of an 8-hour work day.

Dust

The second factor in the OSHA PEL

How much silica dust is in the air I breathe, and what are my exposure levels?

This depends on a number of factors:

  • What type of material is being cut?
  • How much material is being removed in a cut?
  • What is the silica content of that material?

Using masonry as an example, our studies have shown up to 9 million micrograms of respirable crystalline silica can be released into the environment in a single common paver cut. That’s enough silica dust to exceed 40 years worth of exposure within the OSHA PEL.

For the average contractor, this means you should understand the exposure levels created by the common work practices on your jobs. To accurately measure your exposure levels you need to perform air monitoring tests, an easy and inexpensive process (details below).

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Air Monitoring

Air monitoring uses a battery-operated vacuum attached to an operator’s shirt collar, collecting air samples right where the operator breathes. The results will tell us the exposure level for specific work practices. Once we know exposure level, we can calculate time.
 
What does this mean to you? It means that to know where you stand, you need to do air monitoring to learn what your exposure levels are. This is an inexpensive and relatively easy process for average contractors. Once you learn your exposure levels, you can decide what options are best-suited to control silica exposure on your job sites.

For more information and an inexpensive way to get this done, please contact www.galsonlabs.com. Their typical silica cartridge test is about $35 and the vacuum to run with the cartridge is free to use if you test with galson labs.



Time

The third factor in the OSHA PEL

The Time Factor

Time is the third and final factor used to calculate the PEL. Once we know how much air is being breathed, how much dust is contained within that air, and how much of that dust is respirable silica, we still need to factor the amount of time that air and dust is being inhaled.

We can use what we’ve learned so far to determine the total maximum silica exposure for a person over an eight-hour period. Since a worker breathes 16.8m3 of air in eight hours, and the OSHA PEL is 50μg/m3, the total maximum exposure for eight hours is 840μg (16.8m3 * 50μg).


16.8m3 of air x 50μg of Silica =
840µg in 8 hours TWA

Time Weighted Average (TWA)

Using this chart, it shows that dependent upon the silica content in the breathing zone, an operator can perform a task that could be 200 micrograms or even 400 micrograms per cubic meter and still stay under an 8 hour TWA as long as the exposure in the other 6-7 hours per day is in clean air.

So you see, this allows us to go in for a limited time, 1 hours, 2 hours, 3 hours, into a dusty environment and still keep our 8 hour TWA below safe limits.

To know what your exposure levels are, you will still need to do air monitoring for tasks that might be above 50mc per cm but this still gives you many options for tasks that are required for a short duration of the day.

Know our exposure level, and use the time weighted average to work to your benefit.

Testing Your Silica Dust Exposure

If you’re cutting at an exposure level of 200ug/m3 , you can cut for two hours and still be within the OSHA PEL. In this case your total exposure is 840ug.

 

Education and Silica Dust Solutions

Silica dust is a major problem affecting the construction industry. One thing we know is it won’t go away by ignoring it.

With the new OSHA rule being enforced June 2017, contractors will have two choices: a) address the problem proactively through education and informed decisions, or b) wait until the problem comes to you in the form of a citation, lawsuit, or serious health issues.

What can you do about it? Start with education.

Silica Education

The fact is a majority of those affected by the silica dust problem know very little about it, or even that there is a problem. That’s why the solution must start with education. Use this page and the resources linked below to educate yourself and your workers about silica.

  • Know the Hazard

    Understand the hazard and risks associated with silica exposure.

  • Know the Standards

    Understand the OSHA PEL and what it means to you, your business and your workers.

  • Know Your Exposure

    Understand how to use air monitoring to measure silica exposure levels and understand the results.

  • Know Your Options

    Understand your options, including tools, work practices and educational resources for controlling silica exposure on your job sites.

 

iQ Power Tools and the War on Silica Dust

iQ Power Tools manufactures the world’s first and only power tools with integrated dust collection technology for the concrete, masonry, hardscape and tile industries. As contractors for over 30 years, we dealt with dust problems and breathed the dust ourselves for years.

Our goal is to see the construction industry 100% dust free. We aim to achieve that goal through education and the development of professional tools and technology to eliminate silica dust from job sites.

Know the standard. Know your exposure. Know your options.

And take action.

Resources

About This Page

We make professional tools for contractors to reduce the risk of silica exposure to their workers and make more money on their jobs. The information presented here has been compiled through decades of experience in the construction industry, first-hand research on job sites and years as front-line construction workers.

Silica Expert: Joel Guth, President, iQ Power Tools

  • Journeyman Mason, 25 year mason contractor in three states
  • Founding member of Masonry Industry Training Association (MITA)
  • 10 year Board Member, Mason Contractors Association of California (MCAC/CCMCA)
  • Represented mason contractors association to help rewrite the Cal-OSHA Silica Dust standard
  • Testified during the OSHA public hearings in March 2014

We welcome an ongoing dialogue about silica dust. If you’d like to talk dust with iQ, please contact us here.