This is a testing site only. See the live Public Lab site here »

Passive Particle Monitoring

###Introduction A passive particle monitor measures particles without the use of mechanical or electrical systems, depending instead on natural wind-blown deposition of particles on a collection surface. Passive particle monitoring is frequently used for qualitative "nuisance dust" measurements, and more recently to extrapolate [airborne PM concentrations]( and the direction dust comes from. Passive monitoring promises to be less expensive and more robust than active monitors' mechanical and electrical components, but comes with a different set of challenges. Public Lab is investigating one [promising passive monitor](/wiki/sem-stub-pm) as a tool for measuring airborne PM concentrations. [Read more in Public Lab PM tool development.](/wiki/pm-dev) ###Advantages and Disadvantages **Advantages** | **Disadvantages** --------------------|--------------------- low cost (less than $100 devices) | deployed for 3-7 days, low temporal resolution deployed without electricity | not real-time (results must be analyzed after collection) simple setup and calibration | analysis can be labor intensive or expensive actual particles are collected | particle speciation is limited by method and cost can generate airborne particle concentrations | no way to extrapolate to airborne concentrations of speciated particles may correlate well with [Federal Reference Methods]( | not an officially recognized method electret methods are particle-specific | electret methods are particle-specific ###Devices ####[SEM Stub Monitors](/wiki/SEM-stub-pm) In field testing, these samplers have been demonstrated to vary (CV) only 11.6% from [Federal Reference Methods](, when measuring course particulates (PM10-2.5), making this the most precise published passive particle monitor design (Ott, Cyrs, & Peters, 2008). Public Lab is evaluating the deployment of this technology. [Read More](/wiki/SEM-stub-pm) Developed originally for indoor dust monitoring at the University of North Carolina by Jeff Wagner and David Leith, this tiny monitor (in the middle of the housing, below) consists of a fine mesh cap over top of a Scanning Electron Microscopy (SEM) pin stub, a small aluminum object that looks like a pin. Thomas Peters and Darrin Ott at the University of Iowa added a wind-and-rain housing so the monitors can be used outside. They also added a glass microscope slide cover on top of the stub, allowing lower-cost analysis with a standard visible-light microscope. [![Amber Wise removing a stub cover](//](// [![IMG_20151015_120027-trim.png](//](// Analysis is performed in [ImageJ]( roughly: [![Analysis Steps](//](// [Read More](/wiki/SEM-stub-pm) Citation: Darrin K. Ott, William Cyrs, Thomas M. Peters, Passive measurement of coarse particulate matter, PM10-2.5, Aerosol Science 39:156 – 167, 2008 ###Sticky Pad Monitors Developed to track 'nuisance dust,'(i.e. any visible dust blowing onto properties adjacent from a dust producing industrial operation), sticky pads are pieces of tape that collect wind-blown dust. No system for speciating particles or correlating particle accumulations with airborne concentrations has been developed, however, sticky pads are the only dust monitoring system that records the direction dust came from. The most advanced system, developed at the University of Leeds and spun off into the [DustScan]( company, uses two sticky pads-- a cylindrical pad used to track the direction dust comes from, and an upward-facing sticky pad to track total dust. The devices are made from standard sizes of ABS drainage pipe and commercially available tape. [![DustScan Sticky Pads](//](// For analysis, sticky pads are scanned at low resolution, and the relative darkness or lightness (albedo) is measured by software to quantify dust accumulation. [Read More](/notes/mathew/06-05-2014/the-development-of-stickypad-monitoring) ###Other Passive Monitors ####Vinzents Passive monitor A small dual-sticky pad system designed for indoor use only, with one pad facing up and the other one horizontal. This system uses a similar deposition model as SEM stub monitors, and analysis can be performed using optical microscopy. See: Vinzents, PS. A Passive Personal Dust Monitor. Annals of Occupational Hygiene, 40: 261-80, 1996. Schneider et al. Passive Sampler Used for Simultaneous Measurement of Breathing Zone Size Distribution, Inhalable Dust Concentration and other Size Fractions Involving Large Particles, Annals of Occupational Hygiene, 46:187-195, 2002. ####Exposed Filter Systems ####Ferm Passive Monitor Martin Ferm has developed two different monitors: 1) a series of vertical strings less than 1mm in diameter collect particles from all directions for analysis with mass spectrometry, not investigated because of the expense of analysis. 2) a polypropylene container with an exposed filter, for mass spectrometry. See: Fern, Martin, Development and Test of a Passive Sampler for Fine Particles, Swedish Environmental Research Institute, 2010. ####Einstein–Lioy Deposition Sampler A similar arrangement to the Ferm monitor, with four exposed 37mm filters for mass spectrometry analysis. See: Einstein et al, Design and Validation of a Passive Deposition Sampler, Journal of Environ Monitoring 2012 September ; 14(9): 2411–2420 ####Brown Electret Sampler A system with an 'electret,' or semi-permanent charged material, filter. Requires expensive analytical chemistry methods. See: Brown, R. C., Hemingway, M. A., Wake, D., and Thompson, J. . Field Trials of an Electret-Based Passive Dust Sampler in Metal Processing Industries, Ann. Occup. Hyg. 39:603– 622. 1995 ####Personal Aeroallergen Sampler (PAAS) Unknown operation, couldn't get the article. Support open science. Yamamoto et al. A passive sampler for airborne coarse particles Journal of Aerosol Science Volume 37, Issue 11, November 2006, Pages 1442–1454...

Author Comment Last activity Moderation
Tinashe "You don't state what happens with the 40 images taken. Are they stacked together for analysis or they are analysed individually. " | Read more » over 5 years ago
richardbowman "Hello, "Cambridge" here (though I've actually moved now). You're right, a laser diode would certainly get rid of the chromatic issues. I suspect ..." | Read more » over 5 years ago
mathew "That is an interesting question. I think the laser would get rid of chromatic aberration-- its a single frequency of light-- but I'm not sure that..." | Read more » over 5 years ago
marlokeno "Hi, @mathew and @SimonPyle - Terrific work! After seeing the demonstration mathew gave at the barnraising in November '16, and then looking at Ca..." | Read more » over 5 years ago
SimonPyle "@warren: The link above was the most recent version, though I just added a GNU GPLv3 license and created a github repository:" | Read more » over 5 years ago
mathew "There is a large folder of sample image sets avaialble. I put a smaller set together here:" | Read more » over 5 years ago
mathew "You can see more about the shape descriptors for each particle here:" | Read more » over 5 years ago
mathew "The image analysis creates: perimeter of each particle area of each particle circularity of each particle Circularity is the ratio between the..." | Read more » over 5 years ago
warren "Is there any sample input/output sets from going through this process, manually or automatically? I was thinking that a good test/spec might inclu..." | Read more » over 5 years ago
warren "Hi! Just re-reading, is it right that the image analysis produces (as it's complete output): perimeter of each particle area of each particle ..." | Read more » over 5 years ago
warren "Hi! Is Simon's macro still at the URL listed above? Or is there a more up-to-date version, potentially open sourced? Thanks! " | Read more » over 5 years ago
DavidMack "I would stick with the aluminum. It's probably the most commonly used material for PM monitoring because as you stated non-conducting materials ar..." | Read more » over 5 years ago
mathew "thanks! I've had some trouble getting the illumination aligned with the very tall illumination arm I made. Its complicated as well by the cable of..." | Read more » almost 6 years ago
richardbowman "Hi @matthew, great that you've got some images :) Looking at your graticule, I think your illumination might be misaligned - the blue-yellow gradi..." | Read more » almost 6 years ago
mathew "Flatfield and scale images: " | Read more » almost 6 years ago
mathew "Here are some image sets including a flat field calibration and scale from the PSL imaging. " | Read more » almost 6 years ago
mathew "Here are some image sets including a flat field calibration and scale from the PSL imaging. " | Read more » almost 6 years ago
richardbowman "Brilliant - I've wanted to make a carry case for absolutely ages, but other things keep getting in the way. I'll be excited to see what you come u..." | Read more » about 6 years ago
mathew "a note to myself: I found this article on calibrating microscopes useful background." | Read more » about 6 years ago
mathew "thanks Richard! I'll try the new files soon. I'm excited to contribute some mounting files to the project and a carrying case. Will get on those in..." | Read more » about 6 years ago
richardbowman "Hey, nice work :) I have also had problems with the legs getting detached during printing, and discovered there was a bug in my OpenSCAD code - it..." | Read more » about 6 years ago
mathew "Followup on automating this process " | Read more » about 6 years ago
mathew "Although we are hopeful that Simon's strategies listed here can get us to a particle count, If they aren't sufficient Rongjun Qin recommended we lo..." | Read more » about 6 years ago
mathew "You can get the analysis spreadsheet here: " | Read more » about 6 years ago