Woodworking dust collectors : protecting the health of craftsmen

"Wood dusts of any kind are likely to cause short-term illness and cancer decades after exposure¹". INRS (National Institute for Research and Safety) analyses are unequivocal: wood dusts represent one of the three most important causes of recognized occupational cancers. In the European Union, according to the WHO (World Health Organization), around 3.6 million of workers were exposed to wood dust in the early 2000s, mainly in the construction sector and furniture industry. In the United States, about 600 000 workers were exposed to wood dust.

Faced with this situation, what can one do when working in a craft profession related to wood, highly exposed to particles, risks of occupational asthma, and other irritations, but with limited means to set up their workshop? Wood artisans - joiners, cabinetmakers, carpenters... - how can you improve the air quality of your working environment and protect your health for a limited investment?

If source capture (extraction from machines emitting the most dust) is the generally recommended and used solution, it does not completely prevent the emission of significant amounts of dust into the air, as we will illustrate in this study. TEQOYA air purifiers go beyond mere filtering of polluted air. They actively draw in dust particles and trap them inside the device. In essence, Teqoya purifiers function not only as filters but also as efficient dust collectors.

The study is based on an experiment we conducted over a period of 6 months (December 2022 to May 2023) in partnership with Romain Maldague's cabinetmaking workshop, in order to assess to what extent TEQOYA dust collectors help reduce the exposure of cabinetmakers, as well as other professionals and wood artisans, to particulate pollution.

Phase 1 of the experiment: analysis of air quality in a woodworker's workshop

With a floor area of approximately 80 m² and a significant ceiling height of around 4 meters, the workshop features workstations running along a street-facing bay window, spanning the entire length of the space. On the opposite side, the blind section of the workshop houses a semi-open area where the main machines are located, notably a frequently used sander that represents the primary source of wood dust in the workshop.

Photo 1 : Workshop area by the windows (top) and sander zone (bottom, right side of the image). The sensor is marked by a red circle.

Two air quality monitoring devices, equipped with Tera Sensors NextPM ², were installed in the workshop, one in the "sander" area and the other on a shelf close to one of the workstations, as indicated in photos 1 and 2 (red circle) and the workshop layout plan (Figure 1, letter C).

Figure 1 - Workshop layout and sensor positioning (Phase I of the experiment) for the first two air purifiers (Phase II of the experiment) and the third air purifier (final setup).

The sensors, connected to a server, allowed continuous recording of measurement data at 30-second intervals.

Photo 2 : installation of a particle counter, near the workstations (white object placed on the first shelf, highlighted by a red circle)

During the first three weeks of the experiment (conducted in December and January), the measurements provided an overview of the particle concentration in the workshop's air during working hours, which varied in terms of wood dust emissions.

First, let's recall the recommended reference thresholds for fine particles PM₁₀.³

Figure 2 - The French, European, and World Health Organization (WHO) recommended standards for fine particles PM₁₀

The figure 3 below represents the measurements of PM₁₀⁴ during two of these three weeks of experimentation, the measurements show very high daily peaks (sometimes more than 400 µg/m³), especially in the afternoon when the sander is most frequently used. To put things into perspective, let's recall that the limit value set by the European Union for PM₁₀ pollution is 50 µg/m³ for the daily average. This threshold is practically exceeded every day in the workshop. The daily average often exceeds 100 µg/m³. This level of particle concentration is comparable to what one might encounter in some of the world's most polluted cities.

These initial results clearly demonstrate that, despite the dust capturing mechanisms equipped on the sander (the primary tool generating dust in the workshop), the concentration of wood dust in the air remains remarkably high.

Figure 3 : PM₁₀ for the period from 08/12/2022 au 23/12/2022 (working days, time range from 8:30 AM to 8:00 PM)

The figure 4, which represents PM₁₀ measurements for a single day, not only shows that the level of particles is very high (close to, or exceeding 100 µg/m³) throughout the entire occupancy period of the premises (from around 8:30 AM to 6:30 PM), but also that the wood particles settle slowly (likely due to their mass and lack of ventilation): while the peak of the day is reached around 4:00 PM with approximately 450 µg/m³, the concentration is still at 100 µg/m³ at 6 PM and remains above 15 µg/m³ (the annual threshold recommended by the WHO) until after 9:00 PM.

Figure 4 : PM₁₀ on the day of 09/12/2022 (from 8:30 AM to 12:00 AM)

Phase 2 of the experiment : installation of two woodworking dust collectors.

After this initial indoor air quality measurement campaign, on February 13th, two TEQOYA E500 dust collectors were installed at the wood artisan's workshop. One of them was mounted on a half-partition separating two workstations. The second one was placed near the cabinetmaker's sander, positioned on a shelf (see photos 3 and 4 and Figure 1).

Photos 3 : installation of TEQOYA air purifiers during the experiment

The comparison of Figure 5 below and the previous Figure 4, both representing measurements for a single day, shows that with the air purifiers, the average levels of particles are lower, and the reduction in pollution after the main peak (around 4:00 PM, as observed on the 09/12) is significantly faster (the decrease by a factor of 10 from the pollution peak is approximately twice as fast as without air purifiers).

Figure 5 : PM10 measurements for the day of 24/02/2023 (time range from 8:30am to 12am)

The days represented here were chosen because they exhibit a comparable profile. However, daily variations are significant, depending on the cabinetmaker's activity, machine usage schedules, and the intensity of wood dust emissions. To ensure robustness, the comparison between situations with and without woodworking dust collectors should be conducted over an extended period of time.

The graph below (Figure 6), in the format heatmap, represents the proportion of time spent⁵ over 5 pollution periods⁶. Two successive periods of 11 working days are compared: the first one on the left WITHOUT wood collectors, and the second one on the right WITH wood collectors. It can be observed that the air quality is significantly improved :

• During the period WITHOUT wood collectors, PM10 levels are above 50⁷ µg/m³ for more than 50 % of the time, while they are above this threshold for approximately 30 % of the time during the period WITH wood collectors.
• During the period WITHOUT wood collectors, PM10 levels are below 25 µg/m³ for less than 20 % of the time, while they are below this threshold for approximately 40 % of the time during the period WITH wood collectors.

Figure 6 : distribution of time spent each day (time range from 8:30am to 6:30pm) over 5 ranges of PM₁₀. On the left, the period without air purifiers from 8th to 21st December 2022. On the right, the period with air purifiers from 20th February to 3rd March 2023.

To complement the measurements, an analysis of the chemical composition of wood dust collected on TEQOYA filter plates was conducted. This analysis identified numerous chemical elements, including traces of lead, chromium, antimony, and barium. Some elements, present in significant quantities, may exist in a toxic form (such as phosphorus and gadolinium). The analyses conducted in the workshop do not allow for a definitive conclusion on the toxicity of the emitted particles. However, they encourage adopting the caution recommended by the National Institute for Research and Safety (INRS) regarding the health risks associated with wood dust.

Phase 4 : Optimization of the installation and assessment of the indoor air quality improvement process in the workshop.

Based on the analyses conducted that identified areas for improvement, the decision to make the installation permanent was not replicated identically. Instead, it was optimized and refined to address the specific findings and enhance the overall air quality in the workshop :

• The positioning of wood dust collectors is often recognized as an important lever for their effectiveness. During the experimental phase, the second purifier, which was placed near the sander, was positioned on a shelf in a configuration that did not optimize its pollutant removal capacity (Photos 3). However, due to its compact design and multiple mounting options, the TEQOYA wood dust collector could be relocated without additional cost to a position that facilitated more efficient particle capture right from their emission (Photos 4).
• The acquisition of a third air purifier (air purifier AB in Figure 1) was decided by the cabinetmaker.

Photos 4 : the acquisition of the third air purifier and improvement in the positioning of the one near the sander.

The benefits of this double improvement - adding the third air purifier and relocating the device near the sander - were immediate and remarkable (Figure 7 and 8). This purification system enables an air quality that complies with the WHO recommendations for more than 70% of the time (compared to less than 20% previously) and keeps the PM10 levels below 100 µg/m³ for over 90% of the time.

Figure 7 : distribution of the time spent each day (time range from 8:30 AM to 6:30 PM) across 5 PM10 concentration ranges₁₀. On the left, the period without woodworking dust collectors from 8 au 21/12/2022. On the right, with woodworking dust collectors from 25/05 to the 02/06/2023.

Testimonial from the cabinetmaker Romain Maldague :
“When Mr. Guitton approached me about these air purifiers, I was immediately interested. Having knowledge of the specific occupational hazards in woodworking professions (cabinetmaker, carpenter, joiner, etc.), I couldn't help but be interested in testing his equipment in a professional setting. I have always believed that respiratory issues and, more importantly, the solutions to implement in a workshop are not given enough consideration. Through extensive discussions, the provision of equipment, and various adjustments, we conducted this experiment, which turned out to be successful. Mr. Guitton has been a valuable interlocutor whom I can only encourage in his endeavor.”

Testimonial of Pierre Guitton from TEQOYA:
“I enjoyed conducting this experiment, which allowed us to refine our understanding of how our technology behaves in a craft workshop. It motivated the entire team that worked on it. The impressive level of particle pollution to which woodworking professionals are exposed inspired us all to find a solution! With the contribution of Mr. Maldague, we have advanced our automated device operation solution while providing a useful level of customization.”