Take Control of Wood Dust

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In 2020, many of us are spending more time than ever in the workshop. Whether it’s sketching out your new build or taking the next steps towards finishing a piece, all that extra time in your shop might make you think about making changes to your space. Regardless of the size of your store, improving your dust collection system can be one of the most worthwhile investments for any carpenter. A cleaner store is not only healthier for your lungs, but healthier for your equipment as well. Most importantly, your dust collection plans don’t have to break the bank. Whatever your budget, there is always something you can do better to improve the air quality in your store.

Why wood dust is harmful

The foundation of good dust collection practices starts with understanding why it is needed in the first place. Every carpenter should be aware of the known health risks associated with the byproduct of their businesses: wood dust. Frequent exposure to wood dust can irritate the skin, eyes, and respiratory tract, resulting in a rash, asthma or loss of respiratory function. Of greater concern is the strong and constant association that many studies have found between exposure to wood dust and nasal cavity cancer.[1]

Wood dust is known to be carcinogenic to humans. In his Report on Carcinogens, the National Toxicology Program, a division of the United States Department of Health and Human Services, lists wood dust as one of the substances known to cause cancer in humans.[1]

And it’s the finest dust particles – those 10 microns and smaller – that are the most dangerous. To put that dimension in perspective, consider that a human hair is about 100 microns thick, while airborne dust particles less than 20 microns are invisible to the naked eye.

The problem starts when your respiratory system has to handle large amounts of breathable dust (less than 10 microns in size). Heavy exposure to this dust can overwhelm the lung’s natural defenses and lead to inflammation and swelling of the airways, which cause symptoms such as shortness of breath, increased sputum and cough, nosebleeds, sinus problems or bronchitis. It can also cause an asthma attack or, in the case of western red cedar, cause asthma as an allergic reaction

Over the past 50 years there have been many case studies by carpenters who have reported cancer of the sinonasal cavities and sinuses, such as adenocarcinoma. Several studies have identified oak, beech, birch, mahogany and walnut as the wood species most used by patients.[2]

Reduce exposure: what you can do

There are many misconceptions about what is or isn’t considered effective dust collection among the woodworking community. Regardless of the method used, the primary purpose of dust collection is to limit exposure to wood dust. With this fundamental principle in mind, here are some ways you can achieve this in your workshop.

Wear a respirator

A respirator is the simplest and often cheapest addition to your store’s safety equipment. Ideally you want one approved by the National Institute for Occupational Safety and Health (NIOSH), which will filter 95% or more of airborne particles, depending on the filter class (N95, R99, P100, etc. .). The numbers in the class of a filter (95, 99 or 100) correspond to the filtration level of airborne particles (at least 95%, 99% or 99.97%), while the letters N, R and P refer to the oil resistance filter (N for non resistant, R for rather resistant and P for strongly resistant). HE (High Efficiency Particulate Air) is the only class without a number: it filters at least 99.97% of airborne particles when used with an air purifying respirator. To confirm that you are using a NIOSH approved respirator (yes, counterfeits exist), check the respirator itself or the accompanying packaging for a number starting with “TC”; this is a NIOSH required approval number for all NIOSH approved respirators.[3]

Collect the dust at the source

OSHA recommends installing collectors where dust is produced, such as the dust door of the woodworking machine.[4] It is necessary to place the extractor hood as close as possible to the source of emission: the lathe, the grinder or other woodworking machines. It is imperative that the dust is collected as it is generated and then directed into the collector. If you lose the dust in the air of your shop, the task of collecting it becomes useless. You’ll inhale that dust and sweep it off your cars and the floor.

Maintain sufficient air / CFM volume

Dust capture efficiency can be determined fairly accurately by a quick visual inspection of machinery. Inadequate air volume / CFM allows grinder dust to escape onto the floor and into the air. Ensuring that ducts are large enough in diameter and efficiently arranged are two ways to minimize restrictions on airflow.

Most woodworking equipment requires around 250-1000 CFM. The amount of CFM needed will vary depending on the size and number of woodworking tools operating at the same time. Most mid-sized table saws, planers, and splicers with 2-5 inch diameter ports require approximately 300-600 CFM to clean well (Table: Airflow vs. Pipe Diameter). A machine that sheds a lot of chips or emits a visible plume of fine dust needs more airflow.

Use a high quality filter

The final stage of dust collection is filtering the fine dust. There is no point in going through all the hassles of collecting dust if you still allow the finer dust to pass through the filter and out into the store air. The tiniest dust is the unhealthy to breathe and when it disperses into the air, inhalation is inevitable.

Effective filtration requires a quality filter medium with sufficient quantity / surface area. You want to filter close to 100%, down to the smallest particle (10 microns or less in diameter), what industrial hygienists call the PM10 range.

Filter media certified to a certain standard, such as HEPA (tested to be 99.97% efficient at 0.3 microns) are also a must.

Before buying a vacuum cleaner, there are a few questions to ask about its filtration.

  • What kind of filter is supplied?
  • What is its efficiency index?
  • Is it possible to provide a specification sheet?
  • Has the filter medium been tested by an approved third party agency?

Don’t let dust collection be an afterthought. Follow these basics to ensure a safer, healthier and more pleasant work environment.

Further reading and sources

For a more complete source on CFM discharge volumes, check out Industrial ventilation: a manual of best practices for design by the American Conference of Governmental Industrial Hygienists.

[1] National Toxicology Program. 2016. Report on Carcinogens, 14th Ed.; Research Triangle Park, NC: United States Department of Health and Human Services. https://ntp.niehs.nih.gov/go/roc14.

[2] International Agency for Cancer Research. 1995. IARC Monographs on the Evaluation of Carcinogenic Risks for Humans, n. 62; Wood dust and formaldehyde. https://www.ncbi.nlm.nih.gov/books/NBK493444/.

[3] National Institute of Occupational Safety and Health (NIOSH), National Personal Protective Technology Laboratory. Section 1: NIOSH Approved Respirators. Centers for Disease Control. https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource1quest2.html.

[4] Occupational Safety and Health Administration (OSHA). Wood dust: possible solutions. United States Department of Labor. https://www.osha.gov/SLTC/wooddust/solutions.html.

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