To limit exposure to silica, The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) issued standards in 2018 for both construction and general industry to help protect workers and requires that employers comply with the standard. Exposure to silica in the pest control industry would primarily occur during termite treatments that require drilling into concrete, brick, mortar, or block.
Crystalline silica is a type of mineral and is most commonly found in the form of quartz. It is present in many natural materials such as sand, rock and stone as well as manmade materials such as concrete, brick, block, mortar, tile and in artificial stone. Dust containing crystalline silica can be created when using power tools to chip, cut, drill, saw and grind any of the previously mentioned natural and man-made materials. The dust created during these construction activities contains tiny particles of crystalline silica that can then be breathed into the lungs—hence the name respirable crystalline silica. Breathing in silica can lead to health issues, including silicosis, chronic obstructive pulmonary disease (COPD) and lung cancer. The silica used in pest control products does not fall within this regulation since it is not respirable crystalline silica and does not have the same health hazard.
TASKS THAT COULD EXPOSE WORKERS TO SILICA
Employees must be trained on any specific tasks that could expose them to silica. For termite treatments, that task would be using a handheld or rotary hammer drill. An employer may also implement engineering controls like using a HEPA filter on a vacuum to collect dust or having a vacuum dust collector on the drill itself. Another engineering control that could be implemented would be opening doors and windows when appropriate to increase ventilation. A respirator may be required if work practices and engineering controls do not limit exposure below the permissible exposure limit (PEL). Employers must limit employee exposure to silica on the job below the PEL established by the OSHA standard to 50 μg silica per cubic meter of air.
REQUIREMENTS FOR EMPLOYERS:
- Establish and implement a written exposure plan
- Designate a competent person to implement the written exposure plan
- Restrict housekeeping practices that expose workers to silica
- Offer medical exams every three years for workers who wear a respirator for 30 or more days a year
- Train workers on tasks and operations that may result in silica exposure
- Keep records of objective data and any measurements or medical exams
Depending on the scenario, you may not be subject to medical exams or all of the required records, but you should get training and access to the exposure control plan as well as the standard.
CHOICES FOR EMPLOYERS TO COMPLY WITH THE STANDARD
- 1) Specified Exposure Controls or
- 2) Alternative Exposure Controls
- a) Objective Data (Performance Option)
There are two options for complying with the standard, one of which is using objective data that falls under the alternative exposure control option.
SPECIFIED EXPOSURE CONTROLS
Specified exposure control methods involves following the requirements for engineering and work practice controls listed in Table 1 of the standard. Table 1 from the OSHA standard requires that if you use a handheld, rotary hammer drill then your employer should equip the drill with a dust collection system, follow the manufacturer’s instructions, and use a HEPA-filtered vacuum when cleaning holes. A respirator is not required for this type of work.
ALTERNATIVE EXPOSURE CONTROL METHODS
Alternative exposure control methods require that the employer must determine the amount of silica you are exposed to. One alternative exposure control method that OSHA allows is the performance option. This option allows no extra mitigation if industry-wide data shows that work performed in an 8 hr work shift remains below an action level of 25ug/cubic meter. NPMA solicited an environmental consulting company to collect this data and has provided this data to potentially be used by employers based on their protocols and standards. Training still has to be conducted and access to the OSHA standard must be provided.
PERFORMANCE OPTION AND NPMA SILICA STUDY
To determine the amount of respirable silica termite technicians are exposed to during conventional and exterior perimeter/ limited interior treatments, NPMA worked with Aires Environmental Consulting Company and NPMA member companies to obtain objective exposure data for workers performing slab and foundation drilling. This data can be used by pest controlemployers to claim exclusion from the standard. However, the burden remains on the employer to show that the objective data accurately characterizes employee exposure to respirable silica and is under similar workplace conditions as the conducted study.
For this study, exterior perimeter/limited interior treatments consisted of a continuous treated zone along the exterior foundation of the structure by trenching soil and drilling outdoor slabs. Localized interior treatments were made to areas only where known termite activity was observed. Conventional treatments consisted of all masonry voids being drilled and injected at, or near, ground level indoors. Conventional treatments consist of a higher percentage of indoor drilling. During the treatments, termite technicians wore sampling devices that collected silica particles in the dust and the samples were then sent to a laboratory for analysis.
Concrete drilling was conducted using a rotary hammer drill with a drill bit size ranging from ¼ to ½ inch in diameter. Clean up was performed using either broom sweep up or a standard shop vacuum fitted with a HEPA-filter. The vacuum with a HEPA filter is preferred to limit dust exposure.
RESULTS OF STUDY
Exterior Perimeter/Limited Interior Treatments < 4 hrs/day
Conventional Treatments, Indoor Drilling < 40 min
The results of the study showed that employee exposure during specific tasks performed during termiticide treatments remained below the action level (AL) of 25 µg/m3 as an 8-hour time weighted average (TWA). Based on objective data from two separate sites, TWA exposures during exterior perimeter, localized interior treatment (EP/LI) should not exceed the AL if total drilling is less than 4 hours per day. This assumes an outdoor to indoor drilling ratio of 10:1. For conventional treatments, where indoor drilling may equal outdoor drilling (50:50 ratio), the AL could be exceeded if more than 40 minutes of indoor drilling was performed.
What this means, is that if your company’s standard operating protocol is to perform Exterior Perimeter/Limited Interior termite treatments, and you drill for less than 4 hours each day, then the work should fall below the PEL and the objective data may be chosen by employers to comply with the standard. If your company performs full conventional treatments, with extensive drilling of foundations and slabs, your company may also decide to use objective data if drilling does not exceed 40 minutes of indoor drilling each day. The tasks and workplace conditions must be similar to the study and employers should be able to provide information on their standard procedures and whether they meet the specifications. If a company decides to use the objective data, then they should have a copy of the study readily available and discuss their protocols with you. The NPMA study and a template written exposure plan can be found at this website: https://npmapestworld.org/resourcecenter/safety-osha-resources-toolbox/.
WRITTEN EXPOSURE CONTROL PLAN
Regardless of which control measures are chosen, employers are required to have a written exposure control plan for tasks that may cause respirable crystalline silica exposure, as well as methods for preventing exposure, including housekeeping practices. Employers must also have a designated, competent person to implement the control plan. This person must be able to identify any silica hazards and be able to minimize those hazards. The employer must also let employees know who the competent person is and how to contact that person if they are not on site. If workers wear a respirator for 30 or more days per year, then employers have to offer medical exams every 3 years. Additional information and the standard can be found on OSHA’s website https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1153.
BY BRITTANY CAMPBELL, PHD, BCE, NPMA STAFF ENTOMOLOGIST