Not Just Dust: What Employers and Workers Need to Know about Silica

If you work in construction, general industry, maritime, and occupational health and safety, chances are you have been hearing a lot about respirable crystalline silica recently. In June 2016, OSHA issued its final rule on the harmful substance. The final rule is comprised of two new standards, one for construction and one for general industry and maritime, to be phased in over a five-year period.


So what is respirable crystalline silica, and why is it such a big deal? Respirable crystalline silica is a common mineral found in sand, stone and artificial stone. When workers cut, drill, or grind materials containing crystalline silica, or use industrial sand, they can be exposed to very small silica dust particles, known as respirable particles – small enough to enter the human respiratory system!


The respirable particles can travel deep into an exposed worker’s lungs, potentially causing a number of serious, and sometimes deadly, lung diseases. The most common disease caused by such exposures is silicosis, a chronic disease that involves scarring of the lungs and is often times deadly. A known carcinogen, crystalline silica exposure also causes lung cancer in addition to other debilitating respiratory diseases including chronic obstructive pulmonary disease, and kidney disease. In most cases, these diseases occur after years of exposure to respirable crystalline silica.

OSHA estimates that 2.3 million workers are exposed to silica dust, including 2 million in the construction industry. OSHA projects that the new crystalline silica standards will prevent 642 deaths per year, at minor cost to employers. The net monetary benefits of the new standards are projected to be $7.6 billion annually based on reduced mortality and morbidity related to exposure to crystalline silica (OSHA 2016).


With OSHA’s final rule now in place, employers across the country are working to meet the new requirements to protect their employees. OSHA released the final rule as two separate standards – one for construction and one for general industry and maritime.

OSHA’s final rule establishes a new Permissible Exposure Limit (PEL) for respirable crystalline silica of 50 μg/m3 (micrograms per cubic meter of air), as an eight-hour time-weighted average (TWA) through the use of engineering controls, or if such controls are not effective, the use of respirators. It also establishes an action level of  25 μg/m3 – the level at which medical surveillance, increased industrial hygiene monitoring, or biological monitoring are required.

Silica01Prior to the new crystalline silica rule, there was no universal PEL for all industries and types of crystalline silica. The new rule simplifies exposure limits across all industries and sets a uniform PEL for all workers. The new PEL is roughly 50 percent of the previous PEL for general industry, and roughly 20 percent of the previous PEL for construction and shipyards.

The National Institute for Occupational Safety and Health (NIOSH) first recommended this exposure limit to OSHA over 40 years ago, and the American Public Health Association has also recommended that OSHA adopt this PEL. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an even lower exposure limit of 25μg/m3 of air, averaged over an eight-hour day. OSHA considers a PEL of 50 μg/m3 to be the lowest level that can reasonably be achieved through use of engineering controls and work practices in most affected operations, and while there is still significant risk at the new PEL, it will substantially reduce risk in relation to the old standards.

Other key features of the new rule include requirements for employers to:

  • Measure workers’ exposures to respirable crystalline silica if such exposures may reach or exceed levels of 25 μg/m3 as an eight-hour TWA.
  • Limit workers’ access to areas where they may be exposed to respirable crystalline silica
  • Offer medical exams, including chest x-rays and lung function tests, every three years to workers exposed to crystalline silica at or above the level of 25 μg/m3 as an eight-hour TWA for 30 or more days in a year or to construction workers required to wear respirators for 30 or more days in a year
  • Train workers to limit exposures to respirable crystalline silica
  • Maintain records of workers’ exposure to respirable crystalline silica and employer-provided medical exams

The new standard for construction provides and exemption from the requirement to measure worker exposure for employers who follow the engineering controls and work practices laid out in Table 1 of the new standard. Table 1 details dust control methods for 18 common construction tasks where silica exposure can occur. NIOSH research has shown that by adhering to the work practices and engineering controls laid out in Table 1, worker exposures will be held below the PEL, thus eliminating the need for exposure surveillance. Such an exemption is not present in the standard for general industry and maritime, as it is harder to standardize engineering controls and best practices for such broad workplaces. However, employers in these industries are still required to implement engineering controls and work practices specific to the tasks and equipment used in their workplaces.

Screen Shot 2018-09-26 at 3.48.04 PM
Example of a control detailed in the new standard.

This exemption for the construction industry allows employers to spend less time and money on exposure monitoring, and instead more rapidly and efficiently implement engineering controls and work practices that offer much higher levels of protection. Common engineering controls include applying water at the point where dust is made, and local exhaust ventilation that captures contaminated air at or near the point where it is released.

But, why can’t workers just wear respirators all the time, you ask? In short, respirators are not as protective as engineering controls, and they aren’t always as practical. Respirators need to be fitted to each worker and periodically re-fitted, and require regular maintenance – if a filter or other part is not replaced or maintained properly, workers will continue to be exposed. Respirators must also be worn properly by workers to be effective, and can be burdensome and impractical to wear when performing certain tasks or in hot conditions. In addition, they cannot be used by individuals with certain medical conditions. Respirators should only be used as a “last line” of control, as is encouraged by Table 1 of new silica standard for construction.

Construction worker cutting concrete plate for fence fundation using a cut-off saw.

For employers in Washington State, the rule compliance dates determined by the Washington State Department of Labor and Industries are just around the corner. Construction industry employers in Washington State must comply with all obligations of the rule by October 1, 2018, while all other industries must comply with their obligations by July 1, 2019, with a few exceptions. Employers have until June 23, 2020 to comply with medical surveillance requirements for employees exposed to the Action Level for thirty or more days per year, giving employers ample time to implement controls that bring exposures below the Action Level. For hydraulic and fracturing operations in the oil and gas industry, employers have until July 1, 2022 to comply with the engineering control requirements, since it is a newer industry with less background research having been done on processes and equipment.

Complying with the new rule will save lives—check out the many resources available to help employers and workers reduce silica exposures in the workplace:

The Heartbeat of Health and Safety: OSHA’s New Silica Standard for Construction

OSHA Fact Sheet for Employers in General Industry and Maritime 

OSHA Fact Sheet for Employers in Construction

OSHA FAQs for the New Silica Rule

ASSP Silica Resource Guide for Contractors *NEW*

Silica Hazards Online Course from the Washington State Department of Labor and Industries 

OSHA Crystalline Silica Website 

CPWR “Work Safely with Silica” Website 

Controlling Silica Dust in Construction OSHA Video

Controlling Silica Dust in Construction OSHA Fact Sheets (Task Specific)

Washington State Department of Labor and Industries Silica Website 

2016 Silica Consortium “Understanding the new OSHA standards for Silica dust in the construction industry” White Paper

Tackling Silica Exposures in the Workplace – ERC Trainee Interns at Local Foundry

Oregon OSHA Silica Web Page


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Powered by

Up ↑

%d bloggers like this: