Respirable Crystalline Silica
Breathe Safer

Workers who are exposed to respirable crystalline silica dust are at increased risk of developing serious silica-related diseases. Learn more here about protecting workers from exposure to this serious hazard.

VIEW OSHA TABLE 1: Exposure Control

This reference guide deals only with the standards for respirable silica for the construction industry.


Crystalline silica, is a common mineral found in many naturally occurring and man-made materials used at construction sites. Materials like sand, concrete, brick, block, stone and mortar contain crystalline silica.*

Respirable crystalline silica are very small particles typically at least 100 times smaller than ordinary sand found on beaches or playgrounds. Crystalline silica is generated by high-energy operations like cutting, sawing, grinding, drilling and crushing stone, rock, concrete, brick, block and mortar, or when abrasive blasting with sand. Inhaling crystalline silica particles has been shown to create an increased risk of developing serious illnesses or diseases such as lung cancer, silicosis, and chronic obstructive pulmonary disorder.** Each exposure to silica adds to the lung damage.


Silicosis is a disabling, and sometimes fatal lung disease. When a worker inhales crystalline silica, the lungs react by developing hard nodules and scarring around the trapped silica particles. If the nodules become too large, breathing becomes difficult and death can result. There is no cure for this disease.

* Amorphous silica, such as silica gel, is not crystalline silica.

** For more information please refer to 29 CFR 1926.1153, Appendix B (Medical Surveillance Guidelines) and the Occupational Exposure to Respirable Crystalline Silica Final Rule, 81 Fed. Reg. 16286 (Mar. 25, 2016)

Roadmap for Meeting the Requirements of the Respirable Crystalline Silica IN CONSTRUCTION REGULATION 29 CFR 1926.1153

1. Determine if the silica standard applies to your employees. Could employees be exposed to respirable crystalline silica at or above 25 μg/m3 as an 8-hour time weighted average under any foreseeable conditions, including the failure of engineering controls, while performing construction activities?

NO: No further action is required under the silica standard.

YES: Choose to comply with the standard using either the:
- Specified exposure control methods in Table 1, or
- The alternative methods of compliance

2. Determine what additional requirements you must meet under the standard, based on the compliance method you are following.

Requirement If Fully and Properly Implementing Table 1 If Following Alternative Exposure Controls
Permissable Exposure Limit (PEL) No Yes
Exposure Assessment No Yes
Methods of Compliance No Yes
Respiratory Protection Yes, if respirator use is required by Table 1 Yes
Housekeeping Yes Yes
Written Exposure Control Plan Yes Yes
Medical surveillance Yes, for employees who must wear a respirator under the silica standard for 30 or more days a year.
Communication of Hazards Yes Yes
Recordkeeping Yes, for any employees who are getting medical examinations Yes


The silica standard for construction provides a flexible approach for construction employers to achieve compliance. The standard includes Table 1, which lists 18 common tasks using various types of tools or equipment found at construction sites. For each employee engaged in a task in Table 1, employers who choose to follow the Table for that task are required to fully and properly implement the engineering controls, work practices, and respiratory protection specified in Table 1. Employers who comply with the controls of Table 1 are not required to conduct exposure assessments or comply with a Permissable Exposure Limit (PEL) for those employees.

Employees engaged in the Table 1 task means the equipment operator; helpers, laborers and other employees who are assisting with the task; or any other employee responsible for completing the task. For example, an employee operating a walk-behind saw and another employee helping the operator guide the saw are both engaged in the task. An employee operating a jackhammer would be engaged in the task, but another employee directing traffic near the employee jackhammering would not be engaged in the task. When Table 1 requires respiratory protection, employers must provide respirators to all employees engaged in the task. Employers must describe procedures for restricting access of employees not engaged in the task as part of its Written Exposure Control Plan.

Several entries in Table 1 have requirements for the use of respiratory protection with a minimum “assigned protection factor” (APF). Paragraph (d)(3)(i)(A) of the Respiratory Protection standard (29 CFR 1910.134) includes a table that can be used to determine the type or class of respirator that will provide employees with a particular APF, and it can help employers determine the type of respirator that would meet the required minimum APF specified by Table 1. Employers have the flexibility to provide a more protective respirator to those employees who request one or require the employees to use a more protective respirator. See section on Determining Task Duration and Requirements for Respirator Use for information on how to measure task duration to determine respiratory protection requirements for employees doing one or more Table 1 task.


Respirator requirements in Table 1 are divided by task duration:
- “Less than or equal to four hours/shift” and,
- “Greater than four hours/shift”.

Each of the following scenarios is considered a “shift” for purposes of determining the maximum amount of time that an employee may spend on Table 1 tasks without respiratory protection:
- A standard 8-hour work period;
- A day with a break between work periods (e.g., four hours on, two hours off, four hours on);
- Work periods longer than eight hours;
- Double shifts within a single day;
- A work period spanning two calendar days (e.g., 8 p.m. until 4 a.m.).

Task duration time starts when the operator begins using the tool, and continues to be counted until he or she completes the task. This time includes intermittent breaks in tool usage and clean-up. However, tasks that are performed multiple times per day, during distinct time periods, should be counted as separate tasks, and times should be combined.

The requirement to provide respirators is based on the anticipated duration of the task. Employers must make a good-faith judgment.

Examples of Determining Task Durations

1. Tasks with intermittent breaks. An employee cuts and places bricks, one at a time, for four hours consecutively and then spends 30 minutes cleaning up the saw and emptying slurry or dust collectors. All four hours spent cutting and laying bricks along with the 30 minutes for clean-up count for a total task duration of four and a half hours.

2. Tasks with distinct time periods. An employee cuts multiple bricks for 15 minutes, lays bricks for two hours before returning to cut more bricks for another 30 minutes. The total task duration is 45 minutes of the task’s anticipated duration over the work shift, whether performed continuously or intermittently, based on previous experience and all other available information.

Examples of Respiratory Protection Requirements for Single Tasks in Table 1

1. An employer anticipates that it will take an employee 3 hours to cut concrete walls using a handheld power saw (outdoors). No respiratory protection is required.

2. An employer anticipates that it will take an employee 5 hours to demolish an asphalt road using a jackhammer (outdoors). The employer must provide a respirator with an APF of 10 and ensure that the employee wears it for the entire duration of the task.

3. An employer anticipates that it will take an employee 3 hours to grind a concrete floor (indoors) and, therefore, determines that respiratory protection is not required under Table 1. However, at two hours, the employer determines that it will take more than 4 hours to complete the task. The employer must provide a respirator with an APF of 10 at that time and ensure that the employee wears it for the remaining duration of the task.

Examples of Respiratory Protection Requirements for Employees who do more than one Table 1 Task

1. An employer anticipates that an employee will use a handheld grinder on a concrete wall outdoors for 3 hours and then use a chipping hammer outdoors for 2 hours (total Table 1 task duration of 5 hours per shift). The employer looks in the “> 4 hour/shift” column for each task to determine that no respiratory protection is required during use of the handheld grinder outdoors, but a respirator with an APF of 10 is required during use of the chipping hammer outdoors.

2. An employer anticipates that an employee will use a stationary masonry saw to cut bricks for 1 hour and use a handheld power saw to cut concrete indoors for 1 hour over the course of a shift (total Table 1 task duration of two hours per shift). The employer looks in the “≤ 4 hour/shift” column for each task to determine that no respiratory protection is required during use of the stationary masonry saw, but a respirator with an APF of 10 is required during use of the handheld power saw indoors.

3. An employer anticipates that an employee will drive a half-lane milling machine for 4 hours and then operate a walk-behind milling machine equipped with an integrated water delivery system for 4 hours (total Table 1 task duration of 8 hours). The employer looks in the “> 4 hour/shift” column for each task to determine that no respiratory protection is required for either task.


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