Aerosol Science

Clean Air Delivery Rate (CADR) Testing

Measure how quickly room air cleaners remove smoke, dust, and allergen surrogate particles using controlled chamber decay methods.

We run ANSI/AHAM AC-1-aligned chamber tests using controlled aerosol generation and real-time particle monitoring to calculate CADR at each speed setting.

ISO 17025ANSI/AHAM AC-1ASHRAE 52.2ISO 29462Reviewed 2026-05-15
Request a quoteSubmit a sample

Purpose & when to use

Clean Air Delivery Rate (CADR) testing measures how quickly a room air cleaner removes particles from the air in a controlled chamber using decay methods aligned to ANSI/AHAM AC-1. Optical Particle Counters (OPC) and Condensation Particle Counters (CPC) track concentration decay for smoke, dust, and allergen surrogates. Our methods also align to ISO 29462 and ASHRAE 52.2 and are run within our ISO 17025 quality system:

  1. Benchmarking portable room air purifiers for marketing claims — speed-specific CADR under ISO 29462 supports product comparisons across smoke, dust, and allergen surrogate types.
  2. Quantifying performance by fan speed or operating mode for air purifier design decisions — ISO 29462 decay curve fitting connects mode-level CADR to filter and fan trade-off analysis.
  3. Linking filter media efficiency to whole-device air cleaning — ASHRAE 52.2 framing pairs [filtration efficiency data](/testing-services/particle-aerosol-measurement/filtration-efficiency/) with system-level CADR for integrated product programs.
  4. Verification testing for retail claims on whole-room and large air cleaners — ISO 29462 chamber decay protocol provides a defensible and reproducible comparative basis for product documentation.
  5. Performance drift assessment for filter loading and aging on in-duct and consumer devices — ASHRAE 52.2 particulate efficiency framing documents removal rate changes with service life.

Use CADR testing when particle removal rate, performance at individual speed settings, or comparative benchmarking informs a product or claims decision. Applications range from portable room purifiers and whole-room systems to in-duct commercial air cleaners that require chamber decay characterization.

Air-treatment and room air-cleaning device families

CADR testing applies to room air-cleaning devices where particle removal rate is the primary performance claim — from portable units rated under ANSI/AHAM AC-1 to whole-room and in-duct systems requiring fit-for-purpose chamber decay characterization.

  • Room air purifierPortable room air cleaners
  • Whole-room cleanerHigh-capacity whole-room units
  • In-duct air cleanerCommercial HVAC in-line units
  • Fan-filter boxDIY and modular filter boxes

Instrumentation & measurement ranges

We select the platform based on the surrogate aerosol, target size band, and applicable decay method. Each combination is defined during study planning and documented in the report.

0.3 – 10 µmoptical

Optical Particle Counter (OPC)

Size-resolved number concentration — primary monitor for AHAM-aligned chamber decay studies tracking smoke, dust, and allergen surrogate removal in real time.

0.01 – 1 µmoptical-condensation

Condensation Particle Counter (CPC)

Total particle number concentration for ultrafine and fine surrogate fractions — selected when sub-micron sensitivity or fine-mode decay characterization is required.

11.5 – 30 m³chamber-volume

AHAM-aligned test chamber

Controlled test volume with defined mixing fan placement, sampling port geometry, and background decay characterization — sized to match the ANSI/AHAM AC-1 method intent.

0.1 – 10 µmgenerated-particle

Aerosol generation system

Controlled injection of smoke, dust, and allergen surrogates to reach target starting concentrations — lot-tracked surrogate materials with documented generation settings per run.

Test method options

MethodStrengthsTradeoffAligned with
ANSI/AHAM AC-1 chamber decay CADR (primary standard)
  • Speed-specific CADR for smoke, dust, and allergen surrogates under ISO 29462 — the air purifier benchmark for defensible performance claims.
  • Background decay characterization isolates device contribution; surrogate lot tracking and replicates satisfy quality-system and marketing-file requirements.
Requires disciplined chamber equilibration and background characterization — session time scales with the number of fan speeds and surrogate types tested.
ANSI/AHAM AC-1ISO 29462
ASHRAE-style room decay method (fit for purpose)
  • Flexible for larger devices or non-standard geometries beyond ANSI/AHAM AC-1 sizing — ASHRAE 52.2 framing supports commercial air-cleaner programs.
  • Documents removal rate under ASHRAE 52.2 framing for indoor air quality assessments and occupant-exposure documentation.
Requires careful definition of mixing assumptions — without the AHAM chamber specification, comparability to AC-1-rated products must be stated in reporting.
ASHRAE 52.2
CADR plus filtration diagnostics bundle (fit for purpose)
  • Connects CADR to filter media efficiency and seal performance — ISO 29462 framing supports integrated product analysis across fan speeds.
  • Single campaign delivers CADR by speed with pressure-drop and fractional efficiency data for design trade-off decisions and technical documentation.
More measurement surfaces than a standalone CADR campaign — adds media sample management and engineering setup time to the overall study scope.
ISO 29462
Loading and aging sensitivity study (fit for purpose)
  • Documents CADR drift with filter service life — removal rate versus load drives replacement interval decisions and end-of-life performance claims.
  • Sequential CADR measurements across loading stages confirm whether performance stays within acceptable bounds under the same chamber decay methodology as baseline testing.
Longer total run time than a static CADR campaign — scales with the number of loading stages and required replicates per condition.—

Setup configurations

Every CADR study runs on a configuration matched to the device size, the target standard, and the surrogate aerosol set. Fit-for-purpose setup balances controlled background conditions - defined chamber volume, stable mixing, and repeatable device placement - with the practical operating profile of the device under test. The dimensions below are the levers set at study planning:

Device interfaces

Chamber volume selection, device placement, orientation, and fan-speed setpoints standardized across replicates — inlet and outlet orientation documented to avoid direct jet sampling bias.

Flow & actuation profiles

Defined fan speed settings and stabilization periods per condition — auto-mode and boost-mode characterization added when specific operating modes are part of the performance claim.

Environmental controls

Background decay characterization (device off) before each device-on sequence — temperature and relative humidity characterized and logged throughout to bound environmental uncertainty contributors.

Sample numbers

Replicates per fan speed and surrogate type, with repeated sequences for precision — replicate plan sized to expected variability in decay constants and the decision threshold for the claim.

Media & handling

Surrogate aerosol lot tracking and documented generation settings per run — smoke, dust, and allergen surrogates selected to match the target standard and product claim strategy.

Methods anchored to the standards that matter

CADR studies run within a documented quality system aligned to the chamber decay and air-cleaning standards used to characterize portable and whole-room devices. The four anchors below establish the controls and reporting basis carried through to §7 outputs.

  • ISO 17025AccreditedTesting-laboratory competence — documented methods, calibration traceability, and uncertainty contributors.
  • ANSI/AHAM AC-1AlignedChamber decay CADR method for portable air cleaners — smoke, dust, and pollen surrogate protocols.
  • ASHRAE 52.2AlignedParticulate efficiency framing for air-cleaning devices — MERV-rated performance context.
  • ISO 29462AlignedInternational field and laboratory measurement of air-cleaner performance and removal efficiency.

Key data outputs & reporting

The standard CADR report includes speed-specific removal rate values, fitted decay curves, and replicate statistics. Primary metrics, QA / QC controls, and uncertainty contributors are organized for product files, marketing claims support, or comparative performance documentation. The deliverables below cover that report package. Extended studies comparing device revisions, filter lots, or loading stages also include additional comparison materials for interpreting those conditions.

Primary outputs

  • CADR by fan speed setting for each surrogate aerosol (smoke, dust, allergen) in m³/min, with mean, SD, and CV across replicates.
  • Decay curves (device on and device off) with fitted removal constants — background decay correction applied and documented per run.
  • Uncertainty contributors including particle monitor response, chamber mixing assumptions, surrogate generation variability, and background decay correction.
  • Condition comparisons with summary statistics across fan speeds, surrogate types, and device configurations tested.

Deliverables

#FormatContents
01PDF reportMethods, controls, decay curves, CADR summary, replicate statistics, and uncertainty contributors.
02CSV / XLSX datasetsTime-series concentration, per-condition decay constants, and CADR summary by speed and surrogate.
03FiguresDecay curve overlays, CADR bar summaries by speed and surrogate, and background correction documentation.
Extended deliverables · multi-arm comparability · stability · predicate studies
  • Multi-device comparison pack — Side-by-side CADR overlays and statistical framing for multiple devices, prototypes, or filter revisions.
  • Loading and aging summary — CADR versus load stage with performance envelope for filter replacement interval decisions.

QA / QC & data integrity

For each CADR study, we document QA / QC controls matched to the chamber setup, surrogate selection, and speed settings under test. We perform instrument and system verifications before and after each test set within our ISO 17025 quality system. Calibration records remain traceable from particle counter characterization through the final decay constant and CADR result. Background checks and blank runs are included in every campaign.

Pre- and post-run particle counter verification and calibration logs — confirms instrument sensitivity and background are within acceptance before each surrogate introduction and device-on sequence.

Chamber background runs (device off) and blank runs before each device-on phase — establishes ambient baseline and documents natural decay rate for background correction calculations.

Surrogate aerosol lot tracking and documented generation settings per run — aerosol starting concentration confirmed within acceptance window before timing the device-on decay sequence.

Replicate runs per fan speed and surrogate type with acceptance criteria on decay-curve fit quality and mixing stability — reproducibility confirmed before condition results are finalized.

Chain of custody and configuration documentation — device serial number, fan speed settings, chamber orientation photos, and inlet placement recorded per campaign for traceability.

RESEARCH / THIS WORK IN PRACTICE

Real studies. Measured evidence.

Explore published studies connected to clean air delivery rate testing. Each explains the study question, approach and findings.

View related studies (3)
Air-Cleaner Performance

Glow Guardian Air-Purifying Candle: Concept to Market

The work helped Glow Guardian move from an early concept to a public-facing product story supported by controlled bioaerosol data and a granted patent.

Selected finding
The final broad-range study showed measurable reductions across virus surrogates, bacteria, mold spores, and bacterial endospores.
BioaerosolAir cleanerFormulation development
Air-Cleaner Performance

First-Minute Bioaerosol Testing for Active-in-Air Devices

The method addressed a product-mechanism question that standard chamber decay testing does not isolate: what viable bioaerosol concentration remains one minute after a new challenge enters room air that has already been treated?

Selected finding
The method compared viable bioaerosol concentration after a one-minute post-aerosolization mixing period in matched control and pretreated-room conditions.
Related context

The article distinguishes its timing-specific endpoint from standard chamber decay and CADR testing.

BioaerosolAir cleanerDevice evaluation
Air-Cleaner Performance

School Air Purifier Field Study: Bioaerosols and Absenteeism

The study linked laboratory-style air cleaner evidence with repeated measurements in occupied schools, modeled infection probability, and attendance-related outcomes.

Selected finding
Illness-related absenteeism was also lower during the same seven-week study period, though the article avoids treating attendance differences as proof of causation.
Related context

The article links field observations to controlled particle-decay and equivalent-clean-air context.

BioaerosolAir cleanerField study

Study-specific findings do not guarantee performance for another product.

Why ARE Labs

ARE Labs connects technical topics to practical study design, method selection, controlled aerosol work, and reportable evidence without turning technical pages into sales pages.

Reviewed byJamie Balarashti (25 yrs - cascade & inhalation methods) - Weston Schaper (7 yrs - real-time sizing & nanoparticle work)
17025Accredited testing
900+Studies Performed
17+Years in operation
300+Clients supported

Common questions

Quick answers to the questions air purifier developers, filter suppliers, and product managers ask when scoping a CADR study - surrogate selection, fan speed coverage, chamber sizing, background correction, and deliverables. The answers below are starting points; reach out if your device geometry, operating modes, or claim strategy doesn't match what's shown here, since most CADR studies involve at least one configuration choice customized to the device and regulatory frame.

Q.What is CADR and why does it matter for air purifier products?
A.CADR is the effective volumetric clean-air delivery rate a device provides for particles under a defined chamber decay method. It is the primary performance metric consumers and retailers use to compare air purifiers - speed-specific CADR by surrogate type is the standard claim basis under ANSI/AHAM AC-1.
Q.Do I need to test all three surrogates — smoke, dust, and allergen?
A.Not always. The surrogate set depends on the target standard, claim strategy, and intended use of the product. ANSI/AHAM AC-1 specifies all three surrogates for a full rating, while a narrower program may focus on the surrogate most relevant to the intended use environment.
Q.Can you test CADR at multiple fan speeds in one study?
A.Yes. Speed-specific CADR is a core output and the main decision variable for most programs. We run a separate background-corrected decay sequence and replicate set for each speed setting, documenting both the worst-case and best-case settings.
Q.How do you account for natural particle decay in the chamber?
A.We characterize background decay with the device off before each device-on phase, then subtract the natural decay rate when calculating the device's removal contribution. This corrects CADR for ambient particle loss and is required under ANSI/AHAM AC-1.
Q.Can CADR testing be paired with filter media efficiency data?
A.Yes. We can combine CADR and filtration diagnostics in one campaign, pairing device-level CADR at each speed setting with filter fractional efficiency and pressure-drop data. This links media performance to whole-device air cleaning for design and qualification programs.
Q.What do I receive at the end of a CADR study?
A.Deliverables include a PDF report covering methods, background correction, decay curves, and CADR summaries; CSV / XLSX datasets containing time-series concentrations and per-condition statistics; and decay-curve and CADR bar-chart figures for technical files or marketing documentation.

Standards & guidance

ARE Labs conducts CADR studies in alignment with the chamber decay and air-cleaning standards used to characterize portable and whole-room device performance. When a method falls within our third-party ISO 17025 accreditation, we identify it as accredited. When we follow a standard outside that formal accreditation, we describe the method as aligned or conformant where applicable. The cards below identify the standards most relevant to CADR testing programs.

QA & Regulatory - Accredited

ISO 17025

Testing and calibration laboratory competence — documented methods, uncertainty, and traceabilityView standard ->Aerosol & Particle Measurement - Aligned

ANSI/AHAM AC-1

Chamber decay CADR test method for portable room air cleaners — smoke, dust, and pollen surrogatesView standard ->Aerosol & Particle Measurement - Aligned

ASHRAE 52.2

Minimum efficiency reporting value procedure for HVAC and room air-cleaning filtration systemsView standard ->Aerosol & Particle Measurement - Aligned

ISO 29462

Field and laboratory measurement of air-cleaner performance — particle removal efficiency and CADRView standard ->

Related services & devices

Service

Filtration Efficiency Testing

Pairs with CADR to link filter media fractional efficiency to whole-device particle removal rate — ISO 16890 and EN 1822 framing for filter qualification and design optimization.Read more ->Devices

Portable Air Purifiers

Room air cleaners and portable units — ANSI/AHAM AC-1 CADR testing for smoke, dust, and allergen surrogate removal by fan speed.Read more ->Service

Device Particle Emissions Testing

Complements CADR for air-cleaning devices — emissions characterization documents particles the device generates while CADR quantifies what it removes.Read more ->Devices

In-Duct Commercial Air Cleaners

Commercial HVAC in-line and in-duct units — CADR and filtration efficiency characterization for plasma, UV, and media-based configurations.Read more ->