UPAS v2.1

The Ultrasonic Personal Air Sampler (UPAS) is a wearable device that samples particulate matter (PM) air pollution onto filters. Samples collected with the UPAS can be analyzed to determine:

The average PM mass concentration that was present in the sampled air.
The composition of the PM (for example, the amount that is made up of black carbon—a marker of traffic-related air pollution—or various metals).

The UPAS is smaller, lighter, quieter, more affordable, easier to use, and more robust than conventional particulate matter sampling equipment.

Minimal burden: The UPAS is small, light, and silent enough to be worn in a person’s breathing zone with minimal disruption of work and life activities.

Sampling made simple: It’s easy to set up a sample using our mobile app.

Rich data log: The UPAS v2.1 logs time-resolved GPS, temperature, humidity, light intensity, and motion data to tell you where the device traveled during the sample so you can identify associated pollution sources.

Reliable operation: Active controls maintain the target volumetric flow rate even as environmental conditions change and the pressure drop across the filter increases. The UPAS logs the flow rate and other operational data to facilitate robust sample quality assurance.

Durable construction: The UPAS has been field tested over thousands of hours in large sampling campaigns and challenging environments around the world.

The UPAS has been laboratory- and field-tested alongside conventional personal sampling equipment including the Personal Environmental Monitor (PEM), the Harvard Impactor, the Mesa Labs/BGI Triplex Cyclone, and the Personal Modular Impactor (PMI). Validation data can be found in the following peer-reviewed publications:

Volckens, J., C. Quinn, D. Leith, J. Mehaffy, C. S. Henry, and D. Miller-Lionberg. 2017. Development and evaluation of an ultrasonic personal aerosol sampler. Indoor Air 27:409–16. doi: 10.1111/ina.12318. See Figure 5.

Arku, R. E., A. Birch, M. Shupler, S. Yusuf, P. Hystad, and M. Brauer. 2018. Characterizing exposure to household air pollution within the Prospective Urban Rural Epidemiology (PURE) study. Environment International 114:307–17. doi: 10.1016/j.envint.2018.02.033. See Figure 5.

Pillarisetti, A., E. Carter, S. Rajkumar, B. N. Young, M. L. Benka-Coker, J. L. Peel, M. Johnson, and M. L. Clark. 2019. Measuring personal exposure to fine particulate matter (PM2.5) among rural Honduran women: A field evaluation of the Ultrasonic Personal Aerosol Sampler (UPAS). Environment International 123:50–3. doi: 10.1016/j.envint.2018.11.014. See Figures 2 and 3.

Burrowes, V. J., R. Piedrahita, A. Pillarisetti, L. J. Underhill, M. Fandiño‐Del‐Rio, M. Johnson, J. L. Kephart, S. M. Hartinger, K. Steenland, L. Naeher, K. Kearns, J. L. Peel, M. L. Clark, W. Checkley, HAPIN Investigators. 2020. Comparison of next‐generation portable pollution monitors to measure exposure to PM_2.5 from household air pollution in Puno, Peru. Indoor Air 30:445-58. doi: 10.1111/ina.12638. See Figures 2 and 3.

Li, X., J. Tryner, B. N. Young, L. Hernandez-Ramirez, M. Phillips, S. WeMott, G. Erlandson, G. Kuiper, D. Dean, N. Martinez, L. Sanpedro, S. Magzamen, J. Volckens. 2024. Application and validation of a wearable monitor for assessing time- and location-resolved exposures to particulate matter in California’s Central Valley. Aerosol Science and Technology. doi: 10.1080/02786826.2024.2415481. See Figure 1 and Table 1.

The UPAS can collect PM samples on either 37- or 25-mm-diameter filters. The UPAS is most often used to sample PM onto PTFE (Teflon™) membrane filters with 2-μm pores (we recommend Measurement Technology Laboratories part number PT37P-PF03). Many other filters can also be used in the UPAS; however, there are some air sampling filters that are not compatible with the UPAS. The sample pump that makes the UPAS small, lightweight, and virtually silent also has a lower tolerance for “back pressure” (resistance to flow) than many of the larger, noisier pumps that have been used historically to collect personal air samples. In the table below, we indicate whether various filters can be used to sample PM with the UPAS at flow rates of 1 and 2 L min^-1. For most of the filters listed below, we provide an example part number for the 37-mm version, but performance is typically similar for 37- and 25-mm versions of the same filter. For more detailed information on a larger number of filters, see pages 13-15 and Tables 4-5 in our UPAS v2.1 and v2.1 PLUS User Guide.

Filter type	Pore size (μm)	Example product	Sample flow rate
Filter type	Pore size (μm)	Example product	1 L min^-1	2 L min^-1
PTFE membrane	2.0	MTL PT37P-PF03
PTFE membrane	1.0	Zefon FPTFE137
PVC membrane	5.0	SKC 225-5-37
Quartz fiber	-	Pall Tissuquartz 2500QAT-UP
Glass fiber, grade A-E	1.0	Zefon IW-AE3700
Emfab™ (borosilicate microfiber w/ woven glass, PTFE bonded)	-	Pall TX40HI20WW
Gelatin	3.0	Sartorius 12602--37----ALK
MCE	0.8	SKC 225-1939
Polycarbonate membrane	1.2	Millipore RTTP02500
Polycarbonate membrane	1.0	Sterlitech 1270064
Legend:
Compatible with UPAS
Suitable for use if required by your sampling protocol or analysis method; pump voltage setting required to sample through clean filter is >75% of the maximum recommended value; slight concern about the voltage setting that might be required to sample through a filter that is heavily-loaded with PM
Not recommended or not compatible for use with the UPAS; pump voltage setting required to sample through clean filter is greater than the maximum recommended or maximum allowable value

Exterior size	128 mm × 70 mm × 23 mm
Weight	200 g (without inlet or filter cartridge)
Noise	<45 dB
Flow rate range	1.0 to 2.0 L min^-1 ± 4% (actively controlled)
Size-selective inlets (per relevant EPA, ACGIH, and ISO criteria)	PM_2.5, 1 L min^-1 PM_2.5, 2 L min^-1 Respirable, 2 L min^-1 PM₁₀ / Thoracic, 2 L min^-1
Filter size	37 mm (default) or 25 mm; quick-change filter cartridges for easy in-field handling
Battery type	Li-ion, 24 W-h
Battery endurance	20 to 48 h, depending on filter media and sample settings; extendable via external battery or line power.
On-board sensors monitor:	• Sample flow rate • Air temperature/pressure/relative humidity • GPS location of UPAS (can be deactivated) • Differential pressure across the sample filter • Light (Lux, IR, UV, UV index) • Motion/acceleration (linear & angular, 6 DOF)

A diagram pointing out the features that can be used to distinguish the UPAS v2.0, UPAS v2.1, and UPAS v2.1 PLUS

Access Sensor Technologies has sold three different versions of our Ultrasonic Personal Air Sampler...

A photograph of a workstation with a multimeter, computer, and soldering iron.

Step 1: Fill out the Support Request Form If you think you need to send your UPAS to us for...

A photograph of a person wearing a UPAS v2.1 PLUS on a cross-body backpack strap.

"How do people wear the UPAS?" Below, we discuss factors you should consider when figuring out the...

UPAS v2.1

$1,678.00

UPAS v2.1 only; inlets, cartridges, and other accessories sold separately. Request a quote to receive information about academic and nonprofit discounts. Pricing is only applicable for domestic customers. Contact us for an introduction to one of our excellent international distribution partners for country-specific pricing.

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UPAS v2.1

Which air sampling filters are compatible with the UPAS?

Specifications

Technical Resources

UPAS v2.1 Product Information Sheet

User Guide (firmware versions ≥200)

User Guide (firmware versions ≤158)

Zotero Library

AST UPAS iOS app

AST UPAS Android app

Firmware

R Shiny application

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Which UPAS model do I have?

What to expect when returning your UPAS for service

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UPAS v2.1

Service - UPAS v2.0/v2.1 - Health Check

Service - UPAS v2.0/v2.1 - Recalibrate & Validate Mass Flow Sensor

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