Measurements · Particulate Matter
PM1
Also known as submicron particles
Fine particulate matter ≤1 µm aerodynamic diameter, the finest fraction, which reaches the deep alveolar regions of the lung.
What it is
What is PM1?
PM1 is airborne particulate matter with an aerodynamic diameter of one micron or less: the ultrafine and submicron fraction of the dust suspended in air. These are the smallest particles routinely monitored, far finer than PM2.5 or PM10, and they behave almost like a gas: they stay aloft for long periods, travel far from their source, and follow the airstream deep into the body. PM1 comes overwhelmingly from combustion and high-temperature processes: vehicle exhaust (diesel in particular), wood and coal burning, cooking, wildfires, and industrial emissions. Secondary particles that form in the atmosphere from gaseous precursors such as sulfur dioxide and nitrogen oxides add to it.
Because almost all combustion particles fall within it, PM1 carries the greater part of PM2.5 mass and the deepest lung penetration of the common size fractions.
Health and operational effects
The finer a particle, the deeper it reaches and the longer it lingers. PM1 penetrates beyond the bronchi into the alveolar gas-exchange region of the lungs, and the smallest particles within it can cross into the bloodstream, carrying the toxic and carcinogenic compounds adsorbed on their surface. This is why the submicron fraction is increasingly implicated in the cardiovascular, respiratory, and neurological harm associated with particulate pollution, even though it adds almost nothing to particle mass by weight.
For building operators, clean-process industries, and researchers, PM1 is a sensitive early indicator of combustion and infiltration: it responds to sources that the coarser fractions barely register, which makes it useful for source-hunting and for judging how well a space is protected from outdoor air.
How it is measured
How PM1 Is Measured
Optical (light-scattering) sensors are the standard for continuous PM1: a laser illuminates the airstream and the instrument infers mass concentration from the scattered light. Because scattering weakens sharply as particles shrink, the very smallest ultrafine particles scatter little light, so optical PM1 is best read as the submicron mass within the sensor's detection range rather than a count of every nanoparticle. For research-grade ultrafine work, condensation particle counters and other specialist instruments extend below the optical limit and report number concentration directly.
Built into Aethair PRO and Aethair IAQ2
Measured by the monitor's own sensors, calibrated before it ships: nothing to add.
An instrument on Thiamis2
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing PM1 sensors
For indoor air quality, place sensors in the breathing zone in occupied areas, away from doors, windows, and supply diffusers that would give unrepresentative readings. Because PM1 is dominated by combustion and infiltrates buildings readily, pairing an indoor sensor with an outdoor one is especially revealing: it shows whether a rise originates from an indoor source such as cooking or is being drawn in from traffic outside. For ambient and boundary work, record wind speed and direction alongside so that events can be attributed to their source.
Every device and option that measures PM1 4
| Device / option | Type | Base platform | Measures |
|---|---|---|---|
Aethair PRO built-in sensors | Built-in sensors | Aethair PRO | |
 Aethair IAQ built-in sensors | Built-in sensors | Aethair IAQ | |
 TSI · DustTrak 8530, DustTrak 8530EP, DustTrak 8532… | Particulate & Dust Monitors | Thiamis | |
 Trolex · Air XD (TX8005), Air XD (TX8015), XD ONE (TX8060)… | Particulate & Dust Monitors | Thiamis |
Where it is monitored
Solutions That Monitor PM1
Each one links to the solution page showing what that industry measures it for.
Healthcare Air Monitoring
Often addedClinical air quality, pressurization, and patient safety
Indoor Air Quality
Often addedOffices, schools, homes, and public buildings
Outdoor Monitoring
Often addedContinuous outdoor air quality networks that sit alongside reference monitors
School Air Monitoring
Often addedClassroom CO₂, particulates, and campus IAQ
Wildfire Air Monitoring
Often addedSmoke plumes, black carbon, and community exposure
Article Library
Reading on PM1
Commercial Building IAQ Monitoring: ASHRAE 62.1 & WELL
Indoor air quality monitoring for commercial buildings: what to measure, which standards apply, and how property managers build a program tenants trust.
Wildfire Smoke Air Quality Monitoring: Detection & Response
Wildfire smoke monitoring for EHS and public health teams: real-time PM2.5, the AQI 151 respirator trigger, and how to alert workers before smoke arrives.
Ambient Air Quality Monitoring: What Nonattainment Changes
Ambient air quality monitoring explained: how PM2.5 attainment is measured, what a nonattainment designation triggers, and what site-level monitoring adds.
Aethair IAQ vs Kaiterra Sensedge Mini: IAQ Monitors Compared
Aethair IAQ vs Kaiterra Sensedge Mini compared on connectivity, sensors, accuracy, and platform, and how to choose the right commercial IAQ monitor.
Types of Air Quality Monitors: Indoor, Outdoor, and Combined
Learn the three types of air quality monitors (indoor, outdoor, and combined), what each one measures, and when to use each one.
How to Generate Air Quality & Compliance Reports
Learn how to generate air quality and environmental compliance reports from monitoring data, plus how automated and AI air quality reporting work.
Related
More in Particulate Matter
Questions
PM1 FAQ
What is the difference between PM1, PM2.5, and PM10?
The numbers are size cut-offs: PM1 covers particles up to one micron, PM2.5 up to 2.5 microns, and PM10 up to ten. PM10 includes coarse mechanical dust, PM2.5 adds most combustion particles, and PM1 isolates the finest, submicron fraction that penetrates deepest. Each larger fraction contains the smaller ones, so the differences between them describe the coarse and fine material in the air.
Why does PM1 matter if it weighs so little?
Health risk from particles is driven more by how deep they reach and what they carry than by their mass. The submicron particles in PM1 travel into the gas-exchange region of the lungs and can enter the bloodstream, so they concentrate the toxicity of fine particulate while contributing little weight. That is why PM1 is watched as a sensitive combustion indicator.
Is there a regulatory limit for PM1?
Most air-quality frameworks regulate PM2.5 and PM10 but not PM1 separately, so there is usually no standalone legal limit to compare against. PM1 is therefore interpreted as a trend and as a share of the PM2.5 it sits inside.
How do I monitor PM1?
The Aethair family measures PM1 with a built-in optical particle sensor, alongside PM2.5, PM10, and particle count, so the whole fine-particle picture comes from one instrument. For research into ultrafine particles below the optical range, a Thiamis gateway can carry a specialist counter. Use the configurator to combine PM1 with PM2.5, black carbon, and the other parameters your site needs.
Monitor PM1 on the Record
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