Silica Dust Compliance for General Industry Q&A

The silica dust compliance deadline for general industry is coming up fast. To help companies meet this deadline, we recently hosted a webinar entitled “Silica Dust: Practicing Proactive Housekeeping for General Industry Compliance” (watch the full recording here). The webinar generated an excellent discussion about the new standard and what companies need to do to comply. Below is an edited version of the Q&A.

Topic: Silica dust rule and compliance

Where can I get a copy of the new rule?

Check out OSHA’s Silica Dust Rule page.

Is there a requirement for how often a facility needs to test for silica?

How often monitoring must be done depends on the results of initial monitoring and, thereafter, any required further monitoring, as follows:

• If the initial monitoring indicates that employee exposures are below the action level, no further monitoring is required.
• If the most recent exposure monitoring reveals employee exposures at or above the action level but at or below the PEL, the employer must repeat monitoring within 6 months of the most recent monitoring.
• If the most recent exposure monitoring reveals employee exposures above the PEL, the employer must repeat monitoring within 3 months of the most recent monitoring.
• When two non-initial monitoring results taken consecutively, at least 7 days apart but within 6 months of each other, are below the action level, employers may stop monitoring for employees represented by those results, as long as no changes occur that could reasonably be expected to result in new or additional exposures at or above the action level.

How do you measure silica levels? Can you hire someone to do this?

Yes, you can. Employers must ensure that their silica samples are analyzed by laboratories that meet the qualifications and use methods specified in Appendix A of the standard.

What is the best equipment to use for sampling the air?

See Appendix A of the silica dust standard for more information.

Do you have an example of a written exposure control plan?

See pages 11 to 13 of the Small Entity Compliance Guide for more information and a sample written exposure control plan.

When must employers comply with the medical surveillance requirements of the standard?

Employers are required to offer medical examinations to employees exposed above the PEL for 30 or more days a year beginning on June 23, 2018. Employers are required to offer medical examinations to employees exposed at or above the action level for 30 or more days a year beginning on June 23, 2020.

In regards to medical examinations for 30 days of exposure, what constitutes/qualifies as a day of exposure?  

See previous question for triggers for medical surveillance and pages 15 to 22 of the Small Entity Compliance Guide for more information.

Please explain what it means that the processing of sorptive clay is exempt.

OSHA 1910.1053, paragraph (a), section (iii), states that the standard does not apply to exposures that result from the processing of sorptive clays. These are specific types of clay found in a few geologic deposits in the country that are used in a range of consumer products and industrial applications, such as pet litter and sealants for landfills.

Do U.S. companies have to follow ACGIH limits?  

PELs are legal limits, meaning OSHA can enforce their use and any non-compliance in the U.S. Threshold limited values (TLVs) are recommendations provided by the American Conference of Governmental Industrial Hygienists (ACGIH), a private not-for-profit, nongovernmental corporation. Although industrial hygienists must ensure they meet the PELs set by OSHA, they and their organization may choose to adopt TLVs for certain chemical substances – provided they are appropriate for the application – because TLVs generally are more stringent than PELs. However, TLVs are based solely on health factors, not economic or technical feasibility. For more information, read this article.

Would you say that aluminum oxide is just as hazardous as silica?

A certified and/or qualified industrial hygienist should be consulted to comment on whether aluminum oxide could be used as a suitable substitute for silica sand.

Are disposable respirators acceptable, or are cartridge respirators required to effectively filter out silica?

See OSHA 1910.134, paragraph (g), for more information on the use of respirators.

When using silica in a hood, do you need to do air monitoring or is it not expected to exceed the action level or permissible exposure level?

You should confirm the concentration level of silica dust and the duration of exposure to determine if the worker has been exposed to the action level or permissible exposure level.

Is it acceptable to implement engineering controls and PPE at all times for all applications until we have the means to measure dust levels?

A certified and/or qualified industrial hygienist should be consulted.

Does someone who is exposed to silica not more than the standard allows still need a pulmonary function test? Also, does someone who has been exposed to silica previously need to continue to get pulmonary function tests if they no longer work with it?

See pages 15 to 22 of the Small Entity Compliance Guide for more information on medical surveillance. We also recommend checking with your local OSHA representative for specifics.

What is objective data?

According to OSHA 1910.1053, paragraph (b), section (iii), objective data means information, such as air monitoring data from industry-wide surveys or calculations based on the composition of a substance, demonstrating employee exposure to respirable crystalline silica associated with a particular product or material or a specific process, task, or activity. The data must reflect workplace conditions closely resembling or with a higher exposure potential than the processes, types of material, control methods, work practices, and environmental conditions in the employer's current operations.  

Topic: HEPA filters

What is a HEPA certificate and where are you supposed to obtain one?

HEPA isn’t just a label that vacuum manufacturers can apply to their products. It’s a designation that requires filters to be individually tested and verified that they are 99.97% efficient at trapping and retaining particles down to and including 0.3 microns. Filters labeled HEPA-type, HEPA-like, or something similar, are NOT certified. You as a facility owner, operator, or employee do not need to go and source a HEPA certificate after the purchase of equipment. The manufacturer should provide a certificate and it should be included with the purchase of equipment.

Are HEPA filters for silica dust cleanable and reusable? If so, how often should this be done?

The HEPA filter should not be washed. If it is a washable HEPA filter, then it's not a true HEPA filter and probably does not have a certificate of conformity.

Are certified HEPA filters sensitive to high temperatures such as in a foundry or glass manufacturing setting?

We have high temperature hoses and main filters that can be inserted or upgraded with the vacuum to address what could be a higher temperature than what a normal polyethylene hose could handle. The debris usually is cooled once it gets into the hose, and when it starts moving with air, it begins to cool off quite rapidly. We can put protective measures in place to prevent any hot debris from impacting the main filter or HEPA filter.  

Topic: Housekeeping equipment

How do you prevent a vacuum filter from being clogged?

There are several ways to prevent a filter from clogging. Either a manual filter shaker where you turn the vacuum off, you agitate the main filter very rapidly to slough or knock that dust off the main filter. Or vacuums can be fitted with automatic filter purge systems, whether that's compressed air, an electric filter shaker, or some sort of filter purging using the internal air of the vacuum to purge the cartridges or filters.

Can any of your units be used as portable dust collectors, for example, during special operations or maintenance operations?

The simple answer to that is yes. It depends upon what that application is and whether there is enough airflow of the vacuum. We have some smaller units that are designed for use with a power tool where the power tool plugs into the vacuum and the vacuum powers on as soon as the power tool is activated to facilitate dust collection at the source of the tool.

Does Nilfisk offer centralized vacuum systems? If so, how we do I pursue this?

Yes, we do. Our sales and engineering teams will work together to recommend the best solution for your application needs. Please email us at questions@nilfisk.com and we will connect you to your local Nilfisk representative.

Does Nilfisk have any sample results from portable tool dust collection systems?

We do have some results for our wet/dry line of vacuums. Several of our private label partners have conducted testing with their tools and our vacuums. For more information, email us at questions@nilfisk.com.

Does Nilfisk make floor sweepers?

Yes, we do. We offer a full line of industrial- and commercial-grade equipment in various sizes, configurations, and power sources. For more information, visit our Advance website.

Have you seen any retrofit kits for dry sweepers to make them wet?

Nilfisk has sweepers that have a "dust guard" feature which produces a fine mist at the side brooms to suppress fugitive dust. For more information, visit our Advance website.  

Topic: Collecting and disposing of silica dust

Can HEPA vacuums collect wet material?

Yes they can, if properly outfitted with a cyclonic filter shield or the proper main filter to prevent moisture from impacting and damaging the HEPA filter. Check with the manufacturer.

Do you have to use the vacuum with a bag?

Encapsulation of debris or particulate that has the crystalline silica in it is advised to protect operators and facilities. That can be done a number of ways with either a paper bag or a plastic bag, in some cases known as a Longopac® in the industry.

What procedure do you recommend to minimize exposure while emptying the vacuum or dust collection system?

Maintain the use of personal protective equipment throughout the process.

Where would I dispose of a vacuum bag filled with silica dust?

The actual disposal of the material is up to you. It will depend on the regulations that apply to your jobsite. Remember that silica dust is considered a carcinogen, so all applicable local, state, and federal laws need to be addressed when disposing of that material.  

Topic: Addressing specific applications

In a foundry, is it enough to capture the dust and blow it outside, or do we need further controls?

The EPA and the Pollution Control Agency really frown on you putting hazardous materials back into the environment. Once the debris is drawn out of the facility, they recommend that it be disposed of properly and very similarly to lead, asbestos, or any sort of hazardous material. In some states, crystalline silica is considered a hazardous material, and it has to be disposed of and handled as such. Blowing it outside and letting it be absorbed by Mother Nature is not the answer. Furthermore, it's not just about capturing visible dust. It's also the lighter “invisible” dust that collects up in beams in the structure and/or the HVAC ductwork. For more information, check with your local authorities.

What experience do you have with foundry operation? Can you provide a list of foundry references?

We have worked with small and local to larger facilities in the Midwest and throughout the United States. To request a list of references, email us at questions@nilfisk.com.

Does foundry greensand typically produce respirable silica?

Yes. Concentration levels would need to be determined.

Are there good engineering or administrative controls for the cutting of drywall?

Many construction activities [in the rule] are geared towards the cutting of concrete and asphalt but there's also information on cutting of drywall and collection. It's treated almost as the same as cutting of concrete in terms of capture at the source is always the best. This can be achieved with a personal or a smaller HEPA unit connected to a shroud right at the source.

How do you keep dust down during an art class that works with clay and what’s the best way to remove dust from the floor?

We suggest you contact a qualified industrial hygienist and/or your local OSHA representative to determine applicability of the standard to your application.

What is your recommendation for clean up after a saw cutting operation?

For dry cutting, there are several options available– see Table 1 of the standard for the construction industry. Wet cutting options are also allowed. Wet/dry vacuums would be suggested for the clean-up of residual water/slurry.

What face velocity should be maintained on a dust collector system when dumping bags of powdered material into a process tank (materials being used are talc and TiO2)?

Consult with an industrial hygienist for the proper collection method and hardware to meet the standard. For more information, watch the webinar recording available here.