55 HEPA filtration Statistics

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These hepa filtration figures cover the measurement periods and populations identified in the available source material. Estimates, surveys and forecasts retain their reported scope.

Key HEPA filtration Statistics

The main findings are:

  • A HEPA filter is specified to remove at least 99.97% of 0.3-micrometer particles under the stated test condition (definition current on accessed EPA page; U.S. definition).
  • In the same household trial, initial filter use during monitored weeks averaged 84% with a 27-percentage-point standard deviation (initial monitored weeks; 126 low-income households).
  • The Los Angeles classroom crossover study covered 17 elementary schools (July 2022–June 2023; Los Angeles Unified School District).
  • A randomized H14 trial assigned 100 adults with moderate-to-severe asthma to active or placebo filtration (8-month follow-up; adult asthma trial population).
  • The EPA definition specifies a minimum 99.97% removal efficiency for 0.3-micron particles, the most-penetrating particle size used for the HEPA performance claim (current EPA definition page accessed 2026-10-04; EPA HEPA definition).
  • In the CDC simulation, HEPA cleaners reduced combined mean aerosol concentration by 49% in the left/right elevated placement, 52% in left/right floor placement and 55% in front/back floor placement (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation).
  • The 0.3-µm test particle is the most-penetrating particle size (MPPS) in the EPA explanation (definition current on accessed EPA page; U.S. definition).
  • Filter use in subsequent monitored seasons averaged 63% with a 33-percentage-point standard deviation (same household trial).
  • The Los Angeles study compared 99 classrooms with HEPA cleaners against 87 classrooms with non-HEPA cleaners (July 2022–June 2023; Los Angeles elementary schools).
  • The H14 trial reported an adjusted Asthma Control Test improvement of β=2.2 for active versus placebo filtration (8-month trial; 100 adults with asthma).
  • In the CDC conference-room simulation, the tested aerosol size range was 0.3 to 3 microns (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation).
  • Center-floor placement of the two HEPA cleaners reduced combined mean aerosol concentration by 65%, compared with 49% to 55% for the other tested placements (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation).
  • EPA states that particles larger or smaller than 0.3 µm are trapped with even higher efficiency than the HEPA test minimum (definition current on accessed EPA page; U.S. definition).
  • When homes were not visited, filter use averaged 34% with a 30-percentage-point standard deviation (unvisited months; same household trial).
  • The classroom cleaner was rated to filter room air 4.8 times per hour in a room up to 72 m² (study equipment specification; classroom intervention).

Contents

HEPA filtration statistics: efficiency, particle size and filter classes

  • A HEPA filter is specified to remove at least 99.97% of 0.3-micrometer particles under the stated test condition (definition current on accessed EPA page; U.S. definition). (What is a HEPA filter?)
  • The 0.3-µm test particle is the most-penetrating particle size (MPPS) in the EPA explanation (definition current on accessed EPA page; U.S. definition). (What is a HEPA filter?)
  • EPA states that particles larger or smaller than 0.3 µm are trapped with even higher efficiency than the HEPA test minimum (definition current on accessed EPA page; U.S. definition). (What is a HEPA filter?)
  • The EPA fact sheet lists ULPA as 99.9995% efficient for particles 0.12 µm and larger (fact-sheet specification; industrial filter classification). (Air Pollution Control Technology Fact…)
  • The same EPA fact sheet lists HEPA as 99.97% efficient for 0.3-µm-or-larger particulate matter (fact-sheet specification; industrial filter classification). (Air Pollution Control Technology Fact…)
  • EPA reports some extended-media filters reaching more than 99.99% efficiency for 0.01-µm particles (fact sheet citing commercial examples; commercial extended-media examples). (Air Pollution Control Technology Fact…)
  • EPA reports some extended-media filters reaching more than 99.9999% efficiency for 0.1-µm particles (fact sheet citing commercial examples; commercial extended-media examples). (Air Pollution Control Technology Fact…)
  • ASHRAE Standard 52.2 assigns non-HEPA/ULPA filters a MERV value from 1 through 16 (ANSI/ASHRAE 52.2-2017; ASHRAE filter test framework). (ANSI/ASHRAE Standard 52.2-2017)
  • In the randomized household intervention, a bedroom HEPA filter reduced measured PM levels by an average of 50% (week-long monitoring across 3–4 seasons; 126 low-income households with children with asthma). (Particulate matter concentrations in residences:…)

A filter-media test specification, not whole-room or whole-appliance removal.

Describes the test point; efficiency varies with particle and operating conditions.

Qualitative comparison, not a single measured whole-device percentage.

Classification comparison; not evidence that every commercial ULPA installation achieves this in a room.

Clean-filter test context applies.

Not the universal HEPA rating; cited examples and conditions apply.

Example capability, not a general HEPA product claim.

MERV is not the same metric as the HEPA 99.97% designation.

Free-standing filter intervention; adherence and household conditions affected results.

HEPA air-cleaner statistics for indoor PM2.5 and wildfire smoke

Use during monitored periods, not necessarily routine long-term behavior.

Decline is study-specific and reflects monitored households.

Self/remote operating context; not a population adoption estimate.

House-level range; results depended on building and operating conditions.

Ratio is not a direct percent removal and combines HEPA with HVAC filtration.

Comparison is observational and location-level.

The accessible abstract does not provide a single percentage; claim is directional.

Range reflects between-house heterogeneity.

Secondary summary in the field-study record; episode and building conditions matter.

HEPA filtration data from homes, classrooms and public buildings

  • The Los Angeles classroom crossover study covered 17 elementary schools (July 2022–June 2023; Los Angeles Unified School District). (Classroom air quality in a…)
  • The Los Angeles study compared 99 classrooms with HEPA cleaners against 87 classrooms with non-HEPA cleaners (July 2022–June 2023; Los Angeles elementary schools). (Classroom air quality in a…)
  • The classroom cleaner was rated to filter room air 4.8 times per hour in a room up to 72 m² (study equipment specification; classroom intervention). (Classroom air quality in a…)
  • The PREACH trial’s HEPA unit had a clean-air delivery rate of 225 and a recommended area of 10.8 m² (342 ft²) (trial equipment specification; inner-city child bedroom/living-room intervention). (Effect of School Integrated Pest…)
  • Mean study-home area in PREACH was 54.9 m² with a standard deviation of 18.6 m² (trial baseline; inner-city asthma homes). (Effect of School Integrated Pest…)
  • Mean bedroom area in PREACH was 10.8 m² with a standard deviation of 3.0 m² (trial baseline; inner-city asthma homes). (Effect of School Integrated Pest…)
  • The PREACH unit’s recommended 342-ft² area was about 3.2 times the study’s mean 120-ft² bedroom area (trial equipment and baseline; PREACH homes). (Effect of School Integrated Pest…)

School-district sample, not all classrooms nationally.

Crossover design and school-specific implementation apply.

Rated capacity, not necessarily achieved effective air changes in occupied rooms.

Manufacturer/model specification used in the trial; CADR units are not stated in the abstract excerpt.

Descriptive sample statistic, not a housing-market average.

Descriptive sample statistic.

Simple comparison of reported areas; does not measure actual cleaning effectiveness.

HEPA filtration statistics in asthma and respiratory-health trials

Single trial population; H14 device results should not be generalized to all HEPA units.

Model coefficient; not a percentage improvement.

Trial estimate; clinical context and baseline definition matter.

Between-group estimated change; not a universal room-cleaner reduction.

Small single-center study; pandemic limited some clinical measurements.

Duration does not establish population-level long-term benefit.

Pollutant improvement did not translate into significant asthma-control, quality-of-life or lung-function improvement.

Trial population was 85% Black and 59% overweight/obese; not nationally representative.

Sample descriptor.

Descriptive trial composition, not prevalence estimates.

Baseline mean before intervention.

Indoor-pollutant outcome; no observable asthma-outcome improvement.

Indoor-pollutant outcome; not a claim about all settings.

Indoor-pollutant outcome.

HEPA particle filtration is not a general gas-removal claim; device/system context matters.

Difference was not statistically significant.

Trial composition, not a population prevalence estimate.

Allergen sensitization was defined as at least one allergen-specific IgE ≥0.1 kUA/L; group percentages are trial descriptors.

Baseline imbalance between randomized groups; not an intervention effect.

Group means from one-week baseline monitoring; not an ambient-population estimate.

Group means from one-week baseline monitoring.

Group means from one-week baseline monitoring; HEPA particle filtration should not be generalized to gas removal.

HEPA vacuum filtration and particle-emission measurements

  • The EPA definition specifies a minimum 99.97% removal efficiency for 0.3-micron particles, the most-penetrating particle size used for the HEPA performance claim (current EPA definition page accessed 2026-10-04; EPA HEPA definition). (What is a HEPA filter?)
  • In the CDC conference-room simulation, the tested aerosol size range was 0.3 to 3 microns (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation). (Efficacy of Portable Air Cleaners…)
  • Two portable HEPA cleaners in the CDC conference-room test provided a combined 5.2 air changes per hour, versus 2 air changes per hour from the room HVAC system (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation). (Efficacy of Portable Air Cleaners…)

This is a filter-performance specification, not a whole-vacuum or room-emission result.

The experiment measured simulated aerosol exposure rather than vacuum-cleaner emissions or disease transmission.

Air-change performance depended on the tested room, device placement and airflow; it is not a vacuum-cleaner rating.

HEPA filtration performance limits, use and operating conditions

  • In the CDC simulation, HEPA cleaners reduced combined mean aerosol concentration by 49% in the left/right elevated placement, 52% in left/right floor placement and 55% in front/back floor placement (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation). (Efficacy of Portable Air Cleaners…)
  • Center-floor placement of the two HEPA cleaners reduced combined mean aerosol concentration by 65%, compared with 49% to 55% for the other tested placements (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation). (Efficacy of Portable Air Cleaners…)
  • Universal masking alone reduced combined mean aerosol concentration by 72%, while masking plus the two HEPA cleaners reduced it by as much as 90% (2021 laboratory simulation; 584-square-foot U.S. conference-room simulation). (Efficacy of Portable Air Cleaners…)

Placement results came from a well-mixed simulated conference room and should not be generalized to every room layout.

This was exposure to simulated exhaled aerosol, not measured infection reduction.

The comparison used manikins and simulated aerosols; it does not estimate real-world COVID-19 transmission reduction.

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