3M Respirator Simple Filter Support Free

thingiverse

Print and use at your own risk, I take no responsibility of the use of this file, your results may vary. A simple 3M respirator filter attachment for the use of your own filtering medium (8 Boiled Preshrunk Cotton T-Shirt layers). Based on NIH paper for Emerging Infectious Diseases, Simple Respiratory Mask Emerg Infect Dis. 2006 Jun; 12(6): 1033–1034. doi: 10.3201/eid1206.051468 PMCID: PMC3373043 PMID: 16752475 Simple Respiratory Mask Virginia M. Dato,corresponding author* David Hostler,* and Michael E. Hahn* https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3373043/ Design philosophy and requirements: Easy and fast to print, minimal parts, support free, tight tolerances, good seal, easy to use, easy to replace filter medium, plentiful and accessible filter medium, large filtering area. Paper above calls for a DIY respirator employing the use of boiling cotton T-shirt to disinfect and preshrink material. T shirt is cut into rectangular sections and layered 8 times (2 layers cross grain, 2 layers straight grain, 2 layers cross grain 2 layers straight grain). Stack this filter medium into filter base and attach top, it will be a tight fit. Use of tape to seal edges if your filtering medium is thick, but this should just snap in tight. Printed at 100% infill, lines pattern. The filter seals well on the rubber on my mask, but you should always cover inlets and do a seal test by breathing in, if the respirator sucks onto face it is an adequate seal. If it leaks readjust fit on face and tighten, purchase appropriate mask size (S, M, L). Paper excerpt: "A commercially available N95 respirator requires a fit factor of 100 to be considered adequate in the workplace. The prototype mask achieved a fit factor of 67 for 1 author with a Los Alamos National Laboratory (LANL) panel face size of 4, a common size. Although insufficient for the workplace, this mask offered substantial protection from the challenge aerosol and showed good fit with minimal leakage. The other 2 authors with LANL panel face size 10, the largest size, achieved fit factors of 13 and 17 by making the prototype mask inner layers slightly larger (22 cm2). We do not advocate use of this respirator in place of a properly fitted commercial respirator. Although subjectively we did not find the work of breathing required with the prototype mask to be different from that required with a standard N95 filtering facepiece, persons with respiratory compromise of any type should not use this mask. While testers wore the mask for an hour without difficulty, we cannot comment on its utility during strenuous work or adverse environmental conditions. We showed that a hand-fashioned mask can provide a good fit and a measurable level of protection from a challenge aerosol. Problems remain. When made by naive users, this mask may be less effective because of variations in material, assembly, facial structure, cultural practices, and handling. No easy, definitive, and affordable test can demonstrate effectiveness before each use. Wearers may find the mask uncomfortable." In the above paper the mask medium offered a substantial protection from challenge aerosol, with the fitment of the mask as the main challenge. With a commercial respirator such as the 3M 6200, 7500(both in photos) users can better overcome those fitment and sealing problems. A combination of a commercial respirator mask and this printed filter holder, and common cotton tshirt medium, it should offer good protection when no other filters can be purchased or obtained. It should also filter better than surgical masks. With all reusable masks, be sure to clean and disinfect surfaces after use and allow to dry. You can also go one step further to seal any printed surfaces with a thin layer of epoxy, CA glue, or clear nail polish to waterproof for washing. Good luck, stay safe. Edit: Use test file for fitting, remixed from user jwmelvin (I had some scale issues with his original file, this test file is correctly scaled) for a quick print and test. Adjust your slicer percentage to increase or decrease scale if fit is too tight or loose (101%, 102%, 99%, etc). It should fit on tightly to the rubber for a good seal. Edit 2: Created a base that is twice as deep as the original just in case someone would like to add an additional layer of activated charcoal in between two layers of cotton for additional filtering of odors. This I did not test but the 3M filters do also employ a similar layer for VOC filtering. Addition excerpt: PLoS One. 2008; 3(7): e2618. Published online 2008 Jul 9. doi: 10.1371/journal.pone.0002618 PMCID: PMC2440799 PMID: 18612429 Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population Marianne van der Sande, 1 , * Peter Teunis, 1 , 2 and Rob Sabel 3 Madhukar Pai, Editor https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2440799/ "It is also clear that home-made masks such as teacloths may still confer a significant degree of protection, albeit less strong than surgical masks or FFP2 masks. Home made masks however would not suffer from limited supplies, and would not need additional resources to provide at large scale. Home made masks, and to a lesser degree surgical masks, are unlikely to confer much protection against transmission of small particles like droplet nuclei, but as the reproduction number of influenza may not be very high [14] a small reduction in transmissibility of the virus may be sufficient for reducing the reproduction number to a value smaller than 1 and thus extinguishing the epidemic [15]. Greater reduction in transmissibility may be achieved if transmission is predominantly carried by larger droplets. In a typical human cough half of the droplets may be small (<10 µm), but these comprise only a small fraction (2.5*10−6) of the expelled volume [12]. Smaller droplets may however more easily penetrate the smaller bronchi and be more effective in transmission [1]. A more detailed analysis of aerosol and droplet inoculation and infectivity may provide better insight into the impact of either transmission mode on population spread." Counter Article against home made filtration media: (though they seem to only use one layer of each filter medium unlike the above 8) Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles Samy Rengasamy, Benjamin Eimer, Ronald E. Shaffer The Annals of Occupational Hygiene, Volume 54, Issue 7, October 2010, Pages 789–798, https://doi.org/10.1093/annhyg/meq044 Published: 28 June 2010 https://academic.oup.com/annweh/article/54/7/789/202744 "The results showed that cloth masks and other fabric materials tested in the study had 40–90% instantaneous penetration levels against polydisperse NaCl aerosols employed in the National Institute for Occupational Safety and Health particulate respirator test protocol at 5.5 cm s−1. Similarly, varying levels of penetrations (9–98%) were obtained for different size monodisperse NaCl aerosol particles in the 20–1000 nm range. The penetration levels of these fabric materials against both polydisperse and monodisperse aerosols were much higher than the penetrations for the control N95 respirator filter media. At 16.5 cm s−1 face velocity, monodisperse aerosol penetrations slightly increased, while polydisperse aerosol penetrations showed no significant effect except one fabric mask with an increase. Results obtained in the study show that common fabric materials may provide marginal protection against nanoparticles including those in the size ranges of virus-containing particles in exhaled breath." In the end please make your own choices to your safety. I think something is better than nothing, but you must make your own choice. Be smart about it as I can see a possibility where it can give potential users an inflated sense of security and therefore take more risks with exposure. This is just intended to be used in good faith where there is no other option.