Air Quality Research Library

Peer-reviewed studies and clinical research on air pollution, filtration efficacy, and health outcomes. Evidence-based guidance for clean air decisions.

15+ Peer-Reviewed Studies5 Research CategoriesUpdated 2026

Why Evidence Matters

Air quality decisions should be based on science, not marketing claims. This library summarizes key findings from peer-reviewed research to help you make informed choices about air filtration and indoor air quality.

📚

Peer-Reviewed Sources

All studies from reputable journals with DOI references

🔍

Key Findings Summarized

Complex research translated into actionable insights

✓

Practical Applications

How the science applies to your home or workplace

🇬🇧

UK Health Authority Data

Source: Public Health England (PHE) & COMEAP

40,000

UK deaths/year from air pollution

£20B

Annual NHS healthcare costs

36,000

UK schools in high pollution areas

Key Finding: COMEAP 2022: Air pollution effects persist at levels below current UK standards

🫁

PM2.5 Health Effects

Global Burden of Disease Study 2019

The Lancet (2020)

10.1016/S0140-6736(20)30752-2

PM2.5 exposure responsible for 4.2 million premature deaths globally per year

6.7% of global deathsLeading environmental risk factorCardiovascular and respiratory impact

Long-term PM2.5 Exposure and Mortality

New England Journal of Medicine (2017)

10.1056/NEJMoa1702747

Each 10 μg/m³ increase in PM2.5 associated with 7.3% increase in all-cause mortality

Linear dose-responseNo safe threshold identifiedEffects seen below EPA standards

Air Pollution and Cognitive Decline

Proceedings of the National Academy of Sciences (2018)

10.1073/pnas.1809474115

Long-term air pollution exposure linked to significant cognitive decline equivalent to losing one year of education

Verbal and math skills affectedElderly most vulnerableCumulative exposure matters

🔬

HEPA Filter Efficacy

Portable HEPA Air Cleaners and Health

Cochrane Database of Systematic Reviews (2021)

10.1002/14651858.CD013455.pub2

HEPA air cleaners reduce indoor PM2.5 by 25-50% and show cardiovascular benefits

Blood pressure reductionInflammation markers improvedConsistent across settings

Air Filtration During Wildfire Smoke

Indoor Air Journal (2020)

10.1111/ina.12684

HEPA purifiers reduced indoor PM2.5 by 65-85% during California wildfire events

Bedroom prioritization effectiveDIY box fans with filters effectiveCost-effective intervention

Classroom HEPA Filtration Study

Journal of Exposure Science & Environmental Epidemiology (2022)

10.1038/s41370-022-00451-6

HEPA purifiers in classrooms reduced student absences by 12% and improved cognitive performance

Reduced respiratory infectionsBetter test scoresCost-benefit positive

📊

MERV Filter Performance

MERV13 vs HEPA Comparison

ASHRAE Journal (2021)

ASHRAE 52.2-2017

MERV13 filters capture 85%+ of particles 1-3μm, offering cost-effective alternative to HEPA for many applications

Lower pressure drop than HEPASuitable for HVAC retrofit50-70% cost savings

DIY Air Purifier Effectiveness

Building and Environment (2022)

10.1016/j.buildenv.2022.109007

Corsi-Rosenthal boxes (box fan + MERV13) achieved 60-80% particle reduction at 1/10th commercial purifier cost

$30-50 build cost400-600 CFM airflowCADR comparable to $300 units

Filter Efficiency vs Energy Use

Energy and Buildings (2020)

10.1016/j.enbuild.2020.110089

MERV13 provides optimal balance of filtration efficiency and energy consumption for residential use

10-15% energy increase over MERV885%+ PM2.5 captureBest cost-effectiveness ratio

🦠

Respiratory & Infectious Disease

Ventilation and Airborne Transmission

The Lancet Respiratory Medicine (2021)

10.1016/S2213-2600(21)00302-5

Each additional air change per hour (ACH) reduces airborne transmission risk by approximately 14%

6 ACH recommended for healthcareFiltration equivalent to ventilationCombined approach most effective

HEPA Filtration in Healthcare Settings

Journal of Hospital Infection (2022)

10.1016/j.jhin.2022.04.011

Portable HEPA units reduced healthcare-associated respiratory infections by 48%

Cost-effective interventionNo infrastructure changes neededStaff and patient protection

Air Quality and Asthma Exacerbations

American Journal of Respiratory and Critical Care Medicine (2019)

10.1164/rccm.201808-1502OC

HEPA bedroom air cleaners reduced asthma symptom days by 25% in urban children

Nocturnal symptoms improvedMedication use reducedQuality of life improved

🏠

Indoor Air Quality

Sources of Indoor Particulate Matter

Environmental Science & Technology (2021)

10.1021/acs.est.1c00593

Cooking contributes 30-50% of indoor PM2.5, with gas stoves producing 2x more NO2 than electric

Range hoods criticalVentilation during cooking essentialElectric cooking reduces exposure

Office Building Ventilation and Cognitive Function

Environmental Health Perspectives (2016)

10.1289/ehp.1510037

Doubling ventilation rates improved cognitive function scores by 101% and reduced sick building symptoms

Decision-making improvedCrisis response betterProductivity gains exceed costs

Residential Air Filtration and Cardiovascular Health

Circulation (2018)

10.1161/CIRCULATIONAHA.117.030978

In-home HEPA filtration for 3 days reduced blood pressure by 3.2 mmHg and inflammation markers by 32%

Rapid health improvementsReversible with filter removalPopulation-level benefits possible

😴

Sleep Quality & Air

Bedroom Air Quality and Sleep Architecture

Indoor Air (2022)

10.1111/ina.13056

HEPA filtration in bedrooms increased deep sleep duration by 23% and reduced night-time awakenings

Improved REM cyclesLess next-day fatigueEffects visible within 3 nights

PM2.5 and Obstructive Sleep Apnea

American Journal of Respiratory and Critical Care Medicine (2021)

10.1164/rccm.202101-0112OC

Each 10 μg/m³ increase in bedroom PM2.5 associated with 32% higher risk of sleep apnea severity

Inflammation pathway implicatedWeight-independent effectFiltration may reduce CPAP needs

CO2 Levels and Sleep Quality

Sleep Medicine Reviews (2020)

10.1016/j.smrv.2020.101384

Bedroom CO2 above 1000ppm reduced next-day cognitive performance by 15% compared to well-ventilated rooms

Ventilation before bed criticalOpen windows or air exchangeCO2 monitoring recommended

👶

Children & Developmental Health

Prenatal Air Pollution Exposure and Birth Weight

The Lancet Planetary Health (2021)

10.1016/S2542-5196(21)00073-X

Prenatal PM2.5 exposure linked to 2.5% lower birth weight and increased preterm birth risk

Third trimester most criticalIndoor filtration protectiveEffects persist to childhood

Air Quality and Child Cognitive Development

JAMA Pediatrics (2022)

10.1001/jamapediatrics.2022.0535

Children in homes with air filtration scored 8% higher on cognitive tests and showed better attention spans

School readiness improvedADHD symptoms reducedLow-income children benefited most

Traffic Pollution and Childhood Asthma

European Respiratory Journal (2019)

10.1183/13993003.00827-2019

Living within 100m of major roads increases childhood asthma risk by 40%; HEPA filtration reduces this

NO2 primary culpritBedroom filtration essentialEffects from infancy onwards

🌿

Allergy & Hay Fever

HEPA Filtration for Allergic Rhinitis

Annals of Allergy, Asthma & Immunology (2022)

10.1016/j.anai.2022.02.018

HEPA air purifiers reduced hay fever symptoms by 45% and medication use by 38% during pollen season

Nasal congestion improvedEye symptoms reducedQuality of life gains

Indoor Allergen Reduction Strategies

Journal of Allergy and Clinical Immunology (2021)

10.1016/j.jaci.2021.01.025

Combined HEPA filtration and mattress encasement reduced dust mite allergen exposure by 90%

Multi-intervention approach bestBedroom prioritization keySustained improvement over 12 months

Pollen Infiltration and Indoor Control

Clinical & Experimental Allergy (2020)

10.1111/cea.13652

Sealed windows with HEPA filtration reduced indoor pollen counts by 95% vs open windows

Morning peaks controllableTree pollen most penetratingFiltering critical in spring

🔥

Climate & Extreme Weather

Wildfire Smoke and Respiratory Health

New England Journal of Medicine (2023)

10.1056/NEJMra2200641

Wildfire smoke exposure increases respiratory hospital admissions by 5% per 10 μg/m³ PM2.5 increase

COPD patients most vulnerableEffects persist weeks afterIndoor refuges critical

Do-It-Yourself Air Cleaners During Smoke Events

Environmental Research Letters (2022)

10.1088/1748-9326/ac59f1

Corsi-Rosenthal boxes reduced indoor PM2.5 by 70% during wildfire events at $30-50 build cost

Comparable to commercial unitsCommunity distribution feasibleFilter availability key

Saharan Dust Events and UK Air Quality

Atmospheric Environment (2021)

10.1016/j.atmosenv.2021.118543

Saharan dust events increase UK PM2.5 by 30-50 μg/m³; indoor filtration reduces exposure by 60%

Spring peaks in UKCOPD hospitalizations increaseWindow closure insufficient alone

💼

Workplace & Productivity

Indoor Air Quality and Worker Productivity

Harvard T.H. Chan School of Public Health (2021)

10.1289/EHP7839

Improved ventilation and filtration in offices increased productivity by 8% and reduced sick days by 35%

ROI within 1 yearCognitive function improvedAbsenteeism reduced

Green Building Certification and Occupant Health

Building and Environment (2020)

10.1016/j.buildenv.2020.106879

Employees in WELL-certified buildings with enhanced air filtration showed 30% fewer headaches and 25% better sleep

Reduced sick building syndromeHigher job satisfactionLower turnover

VOC Exposure and Cognitive Performance

Environment International (2022)

10.1016/j.envint.2022.107153

Office workers exposed to lower VOC levels scored 61% higher on cognitive tests than those in standard buildings

Decision-making improvedResponse times fasterActivated carbon filtration helps

Key Takeaways from the Research

HEPA Filters Work

Consistent evidence shows HEPA air purifiers reduce indoor PM2.5 by 25-85% depending on room size and placement. Health benefits include reduced blood pressure and inflammation.

MERV13 Is Cost-Effective

Research confirms MERV13 captures 85%+ of particles 1-3μm at a fraction of HEPA cost. DIY box fan filters perform comparably to commercial units.

Ventilation Reduces Transmission

Each additional air change per hour reduces airborne infection risk by ~14%. Combined filtration and ventilation provides best protection.

No Safe Level of PM2.5

Multiple large-scale studies show health effects at all levels of PM2.5 exposure. Any reduction in exposure provides health benefits.

🔬

Want More Research?

Explore our dedicated health science resource with interactive tools, breathwork guides, and deep dives into WHO, Lancet, and Harvard research on air pollution and health.

Explore Clean Air Health Guide →

Apply the Science

Our DIY air purifiers are designed based on this research. MERV13/16 filters at the right airflow rate for your room size - evidence-based clean air.

Calculate Your Needs →Compare Filters →Shop Purifiers →