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ENERGY SAVINGS in BUILDINGS
ENVIRONMENTAL HAZARDS GUIDE
AIR POLLUTANTS, COMMON INDOOR
ALLERGEN TESTS for BUILDINGS
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
FLOODS IN BUILDINGS-priorities
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
MOLD: A COMPLETE GUIDE TO MOLD
MOLD INFORMATION CENTER
ACCURACY OF VARIOUS MOLD TEST METHODS
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
CLEARANCE INSPECTIONS - MOLD CLEANUP
DO IT YOURSELF MOLD CLEANUP
ENERGY SAVINGS in BUILDINGS
ENERGY SAVINGS PRIORITIES
ENERGY SAVINGS RETROFIT CASE STUDY
ENERGY SAVINGS RETROFIT LEAK SEALING GUIDE
ENERGY SAVINGS RETROFIT OPTIONS
FIND MOLD in BUILDINGS, HOW TO
FUNGICIDAL SPRAY & SEALANT USE GUIDE
HIDDEN MOLD, HOW TO FIND
HUMIDITY CONTROL TO PREVENT MOLD
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
  Health Effects of Air Pollutants
  Common Indoor Air Pollutants
  Key Strategies for Improving Indoor Air Quality
  Whole House Ventilation Strategies
  Exhaust-Only Ventilation
  Supply-Only Ventilation
  Balanced Ventilation
  Air Filtering Strategies
  Particles in Indoor Air - Chart
  Quick Guide to Gases
  Air-Cleaner Types
    Particulate Air Cleaner Table
  Air Filter Effectiveness
  Real-World Effectiveness of Air Cleaners
  Finding & Reducing Air Pollutants
  Radon Hazards
  Formaldehyde Hazards
  Biological Pollutants
  Volatile Organic Compounds VOCs
  Pesticide Exposure Hazards
  Lead Exposure Hazards
  Asbestos Exposure Hazards
  Carpeting and Indoor Air Quality
  Combustion Appliance Contaminants
  Backdrafting Appliances
  Fireplace & Woodstove Contaminants
  INDOOR AIR HAZARDS TABLE
  INDOOR COMBUSTION PRODUCTS & IAQ
  ODORS, Smells, Gases in Buildings-Diagnosis & Cure
INDOOR AIR QUALITY METHODS COMPARED
LEAD POISONING HAZARDS GUIDE
MILDEW in BUILDINGS ?
MILDEW ERRORS - MOLD PHOTOS
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD AGE - Old is the Mold?
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD APPEARANCE - STUFF THAT IS NOT MOLD
MOLD ATLAS & PARTICLES INDEX
MOLD BY MICROSCOPE
MOLD CLASSES, HAZARD LEVELS
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP COMPANIES
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD CLEARANCE INSPECTIONS
MOLD DETECTION & INSPECTION GUIDE
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MOLD KILLING GUIDE
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Air cleaner installed in central air conditioning duct system (C) Daniel Friedman

Indoor Air Filtering & Air Cleaner Equipment Guide
InspectAPedia®  -    

  • How to choose air filters or air cleaners for effective improvement of indoor air quality
  • Table of types of particles in indoor air
  • How to use air filters or air cleaners to removing or keep out indoor contaminants
  • Best methods for cleaning & filtering indoor air
Our site offers impartial, unbiased advice without conflicts of interest. We will block advertisements which we discover or readers inform us are associated with bad business practices, false-advertising, or junk science. our contact info is at InspectAPedia.com/appointment.htm.

Here we discuss choosing and using different types of air filters or air cleaners to improve indoor air quality in homes. We include a table of the types of particles found in indoor air, particle sizes, and type of filter needed to remove them. We also include a quick guide to the common hazardous gases found in indoor air. We point out which filter types are effective for different indoor air particle or gas contaminants, and how to buy and use air cleaners. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons.

For optimum filter placement, design, and filtration alternatives on central heating and air conditioning systems, see AIR FILTERS for HVAC SYSTEMS and OPTIMUM INDOOR AIR FILTERS. See ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY for our full list of environmental hazard identification and remedy related to buildings

© Copyright 2010 Daniel Friedman, Steve Bliss, Wiley & Sons, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Air Cleaning & Filtering Strategies to Improve Indoor Air Quality

As noted in Best Practices Guide to Residential Construction:

There are many types and sizes of air cleaners and filters on the market, both stand-alone units and those integrated with HVAC equipment. Different types of air cleaners work on different types of pollutants and none handles everything. The effectiveness of a device depends on a number of factors including the type and efficiency of the filter, how much air flows through it, how well the polluted air reaches the filter, and how effectively the clean air is delivered to occupied areas. (Some small units tend to draw in the same air they just exhausted, creating a short circuit with little impact on the larger space). Also, with electronic air cleaners, performance drops off rapidly if the filters are not kept clean.

Another limiting factor is that many allergies are linked to larger particles, such as pollen, house dust, animal dander, and some molds, that are more likely found settled on surfaces than suspended in the air. A high-efficiency vacuum is needed for these, not an air cleaner.

Particles vs. Gases in Indoor Air

Some filters are effective with particles, such as dust and pollen, and others are effective with gases, such as combustion fumes and formaldehyde. Certain pollutants such as tobacco smoke contain both gases and particles, so they require two types of filters for effective removal.

Particles in Indoor Air - Particulates, Health Effects, & Air Filter Efficiency Chart

Table of particle size vs air filter effectiveness (C) J Wiley, Steven  Bliss

Sometimes called “particulates,” these are small solid or liquid particles suspended in the air. They can be captured in mechanical or electrostatic filter elements. How many get captured depends on the size of the particle along with the type, size, and efficiency of the filter and the rate of airflow.

See the particle size and filter type efficiency chart at left.

Tiny respirable airborne particles, .01 to 5 microns in size, invisible to the naked eye, pose the greatest risk to health because they stay airborne for many hours, almost indefinitely when riding air currents, they move through a building much like a gas, passing through even very small openings where air leaks are present, and because they are breathed deeply into the lungs.

Larger inhalable airborne particles 10 microns and above, (more likely to be trapped in the nose) are more often irritants and allergens (such as pollen grains or insect fragments and fecal pellet fragments in dust). HEPA filters provide the best filtering performance across all particle sizes. As a reference to size, the diameter of a typical human hair is 25 to 60 microns.

Best Practices Guide Source: reprinted in the original text cited above, with permission from Oikois.com (C) 1994 Iris Communications, Inc.

Respirable airborne particles. These are small, invisible particles, typically ranging in size from 0.5 to 2.5 microns (millionths of a meter) that can penetrate deep into the lungs and cause acute or chronic illnesses. Examples include asbestos, viruses, bacteria, and the particles in tobacco smoke. Other sources include unvented kerosene and gas space heaters, woodstoves, fireplaces, poorly adjusted furnace flues, and cracked heat exchangers. Health effects vary with the type of particle, degree of exposure, and individual sensitivity, and range from eye and respiratory irritation to chronic diseases, such as cancer.

Inspirable airborne particles. Particles ranging in size from about 2.5 to 10 microns include dust, pollen, animal dander, and some mold spores. These can be inhaled, but they generally do not penetrate deeply into the lungs. They may cause allergic responses and other health problems in some individuals.

Visible dust found in indoor air. Most particles over 10 microns get trapped in the nose and upper airways and do not generally cause health problems.

Quick Guide to Gases as Contaminants & Hazards in Indoor Air

Gaseous pollutants include combustion gases and a huge array of organic chemicals that have been detected in homes. Gaseous organic compounds can originate indoors from combustion appliances, cigarette smoking, cleaning and personal hygiene products, or hobby materials, or can outgas from building materials, such as pressed wood products, paints, adhesives, and caulks. Others, such as auto emissions and pesticides, originate out of doors and are drawn into the home with outside air.

Health effects vary with type of pollutant, level of exposure, and individual sensitivity, and range from eye and respiratory irritation and allergic responses to cancer and other serious diseases affecting the respiratory, liver, cardiovascular, and nervous systems.

Gaseous pollutants can be removed from the air by passing them through special adsorbents, such as activated carbon, that adhere to the gas molecules.

Radon & Other Gas Hazards in Indoor Air

Radon is a radioactive gas that may enter a building from soil or groundwater. The gas breaks down into short-lived particles, which can get trapped in the lungs and cause cancer. Although some adsorbents can reduce radon gas levels and some high-efficiency filters can trap radon progeny, this has not been adequately tested and is not currently endorsed by the EPA as a radon mitigation method.

For a detailed list of articles about various indoor gas hazards, gas testing equipment, and gas testing methods, see our GASES, EXPOSURE, TESTING article links below.

Also see A Guide to Reducing Exposure to Formaldehyde Hazards in Indoor Air

See Radon Hazards in Buildings: health effects, measuring, remediation guide for details.

See Carpeting and Indoor Air Quality, Health Effects for carpet, carpet padding, adhesive outgassing.

VOCs as indoor gas contaminants are discussed at Guide to Sources & Remedies for Volatile Organic Compounds VOCs as Indoor Air Contaminants.

-- Adapted with permission from Best Practices Guide to Residential Construction.

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Technical Reviewers & References

  • InspectAPedia.com® - Daniel Friedman
  • Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education. Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
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Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

ENVIRONMENTAL HAZARDS GUIDE
AIR POLLUTANTS, COMMON INDOOR
ALLERGEN TESTS for BUILDINGS
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
FLOODS IN BUILDINGS-priorities
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
GASES, EXPOSURE, TESTING
  Carbon Dioxide - CO2
Carbon Monoxide - CO
GAS MEASUREMENT TOOLS
Gas Toxicity Levels
Toxic Gas Exposure Effects
Ammonia Gas
Arsine Gas
Bromine Gas
Carbon Dioxide Gas
Carbon Monoxide Gas
Ozone Gas
Nitrogen Oxides Gas
Propylene Gas
Sulfur Dioxide Gas
Toxic Gas Test Procedures
Allergens, common indoor
Indoor Air Tests
LP & Natural Gas Safety Hazards
Methane Gas Safety Hazards
Natural Gas Combustion Products
Non-regulated particulates
Oxygen - O2
Ozone Warnings
Ozone Hazards
Particulate Testing
Toxic Gas Test Selection
MOLD: A COMPLETE GUIDE TO MOLD
ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
  Health Effects of Air Pollutants
  Common Indoor Air Pollutants
  Key Strategies for Improving Indoor Air Quality
  Whole House Ventilation Strategies
  Exhaust-Only Ventilation
  Supply-Only Ventilation
  Balanced Ventilation
  Air Filtering Strategies
  Particles in Indoor Air - Chart
  Quick Guide to Gases
  Air-Cleaner Types
    Particulate Air Cleaner Table
  Air Filter Effectiveness
  Real-World Effectiveness of Air Cleaners
  Finding & Reducing Air Pollutants
  Radon Hazards
  Formaldehyde Hazards
  Biological Pollutants
  Volatile Organic Compounds VOCs
  Pesticide Exposure Hazards
  Lead Exposure Hazards
  Asbestos Exposure Hazards
  Carpeting and Indoor Air Quality
  Combustion Appliance Contaminants
  Backdrafting Appliances
  Fireplace & Woodstove Contaminants
  INDOOR AIR HAZARDS TABLE
  INDOOR COMBUSTION PRODUCTS & IAQ
  ODORS, Smells, Gases in Buildings-Diagnosis & Cure
INDOOR AIR QUALITY METHODS COMPARED
LEAD POISONING HAZARDS GUIDE
MILDEW in BUILDINGS ?
MILDEW ERRORS - MOLD PHOTOS
MILDEW REMOVAL & PREVENTION
MOISTURE CONTROL in BUILDINGS
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD ATLAS & PARTICLES INDEX
MOLD BY MICROSCOPE
MOLD CLASSES, HAZARD LEVELS
MOLD CLEANERS - WHAT TO USE
MOLD CLEANUP COMPANIES
MOLD CLEANUP GUIDE- HOW TO GET RID OF MOLD
MOLD DETECTION & INSPECTION GUIDE
ODORS, Smells, Gases in Buildings-Diagnosis & Cure
RENTERS & TENANTS GUIDE TO MOLD
SEWAGE BACKUP TEST & CLEANUP
STAIN DIAGNOSIS
TECHNICAL & LAB PROCEDURES
THERMAL TRACKING
TRAPPED MOLD BETWEEN WOOD SURFACES
USING LIGHT TO FIND MOLD
VENTILATION in BUILDINGS
VINYL Siding or PLASTIC Window ODORS in Buildings
VINYL CHLORIDE HEALTH INFO
WATER ODORS

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

  • Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
  • Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Wiley.com and also at Amazon.com. See our book review of this publication.
ENVIRONMENTAL HAZARDS GUIDE

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10/01/2009 - 04/27/2009 - InspectAPedia.com/BestPractices/Air_Filter_Methods.htm - © 2010 - 1988 Copyright Daniel Friedman All Rights Reserved - InspectAPedia® is a Registered U.S. Trademark