Mask Data
Mask Data
The study is provided by ACS Nano that shows fabric material efficiencies and how electrostatic charge plays a role in filtering down to smaller particles of 0.1microns (COVID19 particle size range).
Fitted mask – The studies are done on properly fitted masks. A unfitted mask with gaps can reduce efficiency ratings greater then 60%.
Thread count – A single layer thread count played a factor in mechanical filtration with 80TPI (thread per inch) efficiency at 9% while a 600TPI performed at 79% average on cotton.
Electrostatic charge –Some of the highest filtration seen were in multi-layered blended material to create a electrostatic charge during air movement for smaller particle sizes down to 0.1microns such as cotton/silk, cotton/chiffon, cotton/flannel, cotton quilt with blended material.
Particle size rating – General efficiency ratings sometimes can be misleading due to the different categories of particle size. For COVID19 protection we are focusing on particle range size down to the 0.1micron range for airborne aerosols.
Reusability –There is a lack of information as to material reusability on performance after wash cycles and material break down.
Surgical masks – The variability is due to fit with average test results shown with 50-76% efficiency on less then 0.3 particle size. Originally designed for liquid barrier bacteria protection.
N95 masks – A government efficiency rating of particulates for 0.3microns or larger.
KN95 mask filter insert – We use 2 layers of non woven polypropylene as an outer mechanical barrier while inner layers consist of 100% cotton quilt batting combined with melt blown KN95 blend to create the electrostatic charge during air resistance.
Mechanical Filtration- The combination of mechanical and electrostatic has shown the best results based on material weave density which alone does not provide filtration for smaller particles.
| Flow rate: 1.2 CFM | |||
|---|---|---|---|
| Filter Efficiency (%) | Pressure differential | ||
| Sample/fabric | <300 nm average +/- error | >300 nm average ± error | Delta P (Pa) |
| N95 (no gap) | 85 ± 15 | 99.9 ± 0.1 | 2.2 |
| N95 (with gap) | 34 ± 15 | 12 ± 3 | 2.2 |
| surgical mask (no gap) | 76 ± 22 | 99.6 ± 0.1 | 2.5 |
| surgical mask (with gap) | 50 ± 7 | 44 ± 3 | 2.5 |
| cotton quilt | 96 ± 2 | 96.1 ± 0.3 | 2.7 |
| quilter’s cotton (80 TPI), 1 layer | 9 ± 13 | 14 ± 1 | 2.2 |
| quilter’s cotton (80 TPI), 2 layers | 38 ± 11 | 49 ± 3 | 2.5 |
| flannel | 57 ± 8 | 44 ± 2 | 2.2 |
| cotton (600 TPI), 1 layer | 79 ± 23 | 98.4 ± 0.2 | 2.5 |
| cotton (600 TPI), 2 layers | 82 ± 19 | 99.5 ± 0.1 | 2.5 |
| chiffon, 1 layer | 67 ± 16 | 73 ± 2 | 2.7 |
| chiffon, 2 layers | 83 ± 9 | 90 ± 1 | 3.0 |
| natural silk, 1 layer | 54 ± 8 | 56 ± 2 | 2.5 |
| natural silk, 2 layers | 65 ± 10 | 65 ± 2 | 2.7 |
| natural silk, 4 layers | 86 ± 5 | 88 ± 1 | 2.7 |
| hybrid 1: cotton/chiffon | 97 ± 2 | 99.2 ± 0.2 | 3.0 |
| hybrid 2: cotton/silk (no gap) | 94 ± 2 | 98.5 ± 0.2 | 3.0 |
| hybrid 2: cotton/silk (gap) | 37 ± 7 | 32 ± 3 | 3.0 |
| hybrid 3: cotton/flannel | 95 ± 2 | 96 ± 1 | 3.0 |
AIRBORNE PARTICLES
Why the need to upgrade your face mask in indoor high traffic areas? The CDC released the potential of airborne transmission with higher risk in poor ventilation and indoor spaces. Close contact and prolong exposures are factors with potential airborne suspension time (typically hours).
References: CDC. Scientific Brief: SARS-CoV-2 and potential Airborne Transmission. Updated Oct, 5 2020. https://www.cdc.gov/coronavirus/2019-ncov/more/scientific-brief-sars-cov-2.html
Breathing resistance vs efficiency
A lower filter efficiency is shown to provide less breathing resistance while a higher filtration rating increases breathing resistance. Our filter inserts provide high filtration and is recommended to be matched with adequate ventilation pocket mask in filter area with proper seal/fit. Heavy work activities with high temperature and humidity use may also provide a role in breathing resistance and not recommended for those environments. It is best to test our your compatibility and not recommended for children or certain medical conditions.
References: 3M. Respirators and Surgical Masks: A Comparison. Technical bulletin March, 2020. https://multimedia.3m.com/mws/media/1819575O/respirators-and-surgical-masks-a-comparison-emea.pdf
OSHA. Respiratory Protection. OSHA technical manual Section VIII: Chapter 2. https://www.osha.gov/dts/osta/otm/otm_viii/otm_viii_2.html#10 3M. Children and P2/N95 respirators. Tech update. https://multimedia.3m.com/mws/media/1789220O/3m-anz-2020-tech-update-respirators-usage-children.pdf
Re-using a N95 mask
This study shows a chart of filtration efficiency over a 14 day period with 8 hours of use each day. A brand new N95 mask shows 97% efficiency and dropped to 80% in 14 days. Surgical masks were tested in this study to show 18% efficiency.
References: Du, Jian MMa,b; Zhang, Lijie MSca,b; Liu, Yuhong MDa,b; Shu, Wei MMa,b; Ma, Yan MMa,b; Gao, Jingtao MDa,b; Li, Liang BM. Determination of the optimal time for N95 respirator aerosol infection control. December 11, 2020- Volume 99- Issue 50- P e23709. doi: 10.1097/MD.0000000000023709 https://journals.lww.com/md-journal/fulltext/2020/12110/determination_of_the_optimal_time_for_n95.143.aspx