Preparing for the OSHA Silica Regulation
On September 23, 2017, OSHA began enforcement of its proposed rule outlining a permissible exposure level (PEL) for silica dust on construction sites.
The proposed permissible exposure level (PEL) for silica dust is now set at 50 micrograms of respirable crystalline silica per cubic meter of air (50 µg/m3) over an eight-hour day. Meaning construction sites must reduce crystalline silica dust by 80 percent when compared to the past standard of 250 micrograms per cubic meter of air (250 µg/m3).
Respirable silica dust includes particles with diameters of less than 10 micrometers and is usually produced during the process of milling asphalt and concrete paved surfaces. Crystalline silica dust is a known carcinogen and can cause silicosis, an irreversible occupational respiratory disease, which is often progressive and potentially fatal.
As a member of the Silica/Asphalt Milling Machine Partnership—made up of the National Asphalt Pavement Association (NAPA), milling-machine manufacturers, contractors, academia, and the National Institute for Occupational Safety and Health (NIOSH) — Roadtec, Inc, an Astec Industries company has proactively been working over the past decade to address the best way to protect workers against the exposure of silica in the asphalt industry.
This silica partnership was formed to recognize OSHA’s status on regulation, assess existing data, and determine what actions, controls, and guidance was needed. The partnership’s aim was to consider new controls and best practices in agreeing upon appropriate implementation of procedures.
“Collecting additional data was necessary to fill gaps,” said James Bevill, Roadtec’s Engineering Manager of Development, “We had to understand and evaluate where silica exposures occurred in the milling process and existing controls, and verify machine designs in relation to dust suppression.”
Based on initial testing, actual silica exposure measurements for operators were difficult to obtain in a consistent and comparable manner so that data could be accurately collected for each machine design. Therefore, the decision was made to measure respirable dust levels around the machine as a substitute for silica exposure to operators.
In 2002 at closed airport in Marquette, Michigan, the average respirable dust concentrations were measured on four different milling machines. Based on the findings, optimized water systems significantly lowered respirable dust.
Because optimized water systems alone did not reduce exposure levels to the required amount, the silica partnership also investigated vacuum systems as a way to reduce exposure. Respirable dust and silica concentrations were measured during these tests. Tests proved that vacuum systems delivered best results in combination with optimized water systems to meet OSHA’s permissible exposure limit (PEL) for respirable crystalline silica.
In order to comply with OSHA’s new rules, employers must ensure any employee silica dust exposure is below the permissible exposure level (PEL). Exposure assessments or employee monitoring are usually conducted to verify compliance and are usually done at the employer’s expense, which can be quite expensive and lead to potential liability costs.
However, employers can be exempt from parts of the rule if OSHA-specified controls are used. For example, half lane and larger milling machines, with both vacuum and optimized water systems can cut at any depth without the need for an employee exposure assessment. This means Roadtec’s RX-600e, RX-700e, and RX-900e are exempt because they have these two key systems as standard features.
“According to Roadtec’s Product Manager, Kyle Hammon, “The Roadtec RX-600e was the first cold planer in the industry to be manufactured with both the optimized spray system and vacuum system as key standard components. The dust extraction system improves operator comfort and safety by removing dust and debris from the milling operation through a hydraulic fan at the primary conveyor. The dust is then ejected at the end of the secondary conveyor into the dump truck, away from the operator. The optimized water system consists of two independent spray bars positioned at the front and rear of the cutter housing to provide increased tool life and dust control. Also, two spray nozzles are located at the ends of the primary conveyor for additional dust control. “
“We have taken the industry’s standards and refined them to our own measures, better than the exposure limits laid out by OSHA,” said James Bevill, “Because Roadtec was an original Silica Partnership member, we were proactive in implementing the optimized water and vacuum systems in our equipment. We made them standard components in 2015, before anyone else in the industry, all in the name of safety”
Kyle Hammon concluded, “Assess the status of your fleet. Older equipment will have to be allocated carefully to comply with the OSHA regulation. The range of applications will become smaller for older models unless they are retrofit. Retrofit kits are available to add the dust system and optimized water to older tier 3 Roadtec milling machines.”
You can find the complete OSHA rule at: https://www.osha.gov/silica
You can also find more information here: https://roadtec.com/silica/