I feel we need to up our game when it comes to sawdust control and our exposure to formaldehyde when we machine plywood. Most, but not all plywood is made with some sort of formaldehyde glue. Either urea-formaldehyde for interior plywood or phenol-formaldehyde glue used for exterior plywood. Just knowing of, and choosing plywood that does not contain a formaldehyde glue can be a safer option. Reduced formaldehyde hardwood plywood should conform to ANSI/HPVA HP-1-1994 or the CARB ACTM (American National Standards Institute (ANSI) or California Air Resources Board Air Toxics Control Measure (CARB ACTM) criteria). Plywood, especially new and unsealed plywood will normally outgas low levels of formaldehyde simply due to the manufacturing process. It has been recommended that plywood not be stored in areas where we can be exposed to this gas over the long term. For this reason, plywood should be stored in a well ventilated less populated area.
When plywood is machined, the heat and tooling releases a much larger quantity of formaldehyde gas and resin dust that is concerning. On one hand, supervision of a running Maslow is certainly recommended, but that also puts us in the area of higher concentration of formaldehyde gas and resin dust. The formaldehyde resin dust is a hazard, so if your collection method is poor or completely lacking you are at risk. Even the best filter system will not be effective against the formaldehyde gas as it will simply pass through any particulate filtering process. There are active carbon filter masks that can provide respirator protection against formaldehyde gas.
"Formaldehyde exposure may potentially cause a variety of symptoms and adverse health effects, such as eye, nose, throat, and skin irritation, coughing, wheezing, and allergic reactions. Long-term exposure to high levels of formaldehyde has been associated with cancer in humans and laboratory animals. Formaldehyde can affect people differently. Some people are very sensitive to formaldehyde at a certain level while others may not have any noticeable reaction to the same level".( U.S. Consumer Product Safety Commission, Publication 725 ,(2013) Revision 012013).
OSHA’s permissible exposure limit (PEL) for formaldehyde is .75 parts per million (ppm) as a time-weighted average over an 8-hour period. The short-term, 15-minute exposure limit is 2 ppm. There have been workplace studies that have shown formaldehyde levels from 0.02 ppm to 2.22 ppm depending on many variables (ventilation, heating source (sawdust), locations, basement or above ground, etc) https://www.ncbi.nlm.nih.gov/pubmed/16141685
My recommendations are to have a tighter enclosure around the cutting area and to exhaust the vacuum or dust collector to the exterior. ( FYI: 3D STL files for my tighter router dust collector I use is available at https://www.thingiverse.com/thing:3135499 ). Using a non-formaldehyde plywood is certainly an option, however we still need a good dust collection system. Sensors are available to detect formaldehyde gas but they are expensive. However, if anyone has one I would like to see the data around a Maslow when it is processing plywood. (Note this is also a concern with any laser cutting system cutting plywood.)
Formaldehyde is also a sensitizer, meaning that your reaction to formaldehyde can worsen over time, so negative effects even to the same level, a few PPM, can increase over time. I love my Maslow, however we need to take a good look at our process and products and err or the safer side. Remember, one of the secrets of life is to always be in the control group! Jon