This is a legacy version of the WELL Building Standard. Please check the latest version here.

Air quality standards

Pollutants generated indoors can lead to a variety of symptoms and health conditions. Volatile organic compounds (VOCs), combustion byproducts and airborne particulate matter are known to trigger nausea, headaches, asthma, respiratory irritation and allergies. While ambient outdoor air is often better quality, natural ventilation methods, operable doors and windows, and general building envelope infiltration can diminish indoor air quality if external air quality parameters are poor.

Part 1: Standards for Volatile Substances

The following conditions are met:

a.1 Formaldehyde levels less than 27 ppb.
b.1 Total volatile organic compounds less than 500 μg/m³.
Part 2: Standards for Particulate Matter and Inorganic Gases

The following conditions are met:

a.2 Carbon monoxide less than 9 ppm.
b.2 PM₂.₅ less than 15 μg/m³.
c.3 PM₁₀ less than 50 μg/m³.
d.3 Ozone less than 51 ppb.
Part 3: Radon

The following conditions are met in projects with regularly occupied spaces at or below grade:

a.4 Radon less than 4 pCi/L in the lowest occupied level of the project.
Part 4: Operational Kitchen Air Quality

The following air quality concentrations are met in the commercial kitchen space:

a.2 Carbon monoxide levels less than 35 ppm.
b.2 PM₂.₅ less than 35 μg/m³.
c.2 Nitrogen dioxide less than 100 ppb.
d.129 Formaldehyde less than 81 ppb.
Immune
Cardiovascular
Endocrine
Respiratory
Nervous

Applicability Matrix

Core & Shell New & Existing Buildings New & Existing Interiors
Part 1: Standards for Volatile Substances P P P
Part 2: Standards for Particulate Matter and Inorganic Gases P P P
Part 3: Radon P P P
Commercial Kitchen Education Multifamily Residential Restaurant Retail
Part 1: Standards for Volatile Substances - P P P P
Part 2: Standards for Particulate Matter and Inorganic Gases - P P P P
Part 3: Radon P P P P P
Part 4: Operational Kitchen Air Quality P - - - -

Verification Methods Matrix

Letters of Assurance Annotated Documents On-Site Checks
PART 1 (Performance)
Standards for Volatile Substances
Performance Test
PART 2 (Performance)
Standards for Particulate Matter and Inorganic Gases
Performance Test
PART 3 (Performance)
Radon
Performance Test
PART 4 (Performance)
Operational Kitchen Air Quality
Performance Test
1

U.S. Green Building Council. LEED v4: Reference Guide for Building Design and Construction. Washington D.C.: U.S. Green Building Council; 2013: 37, 43-44, 541-552, 567, 605, 623, 645-53, 658-61, 682-3, 685-6, 723-4.

01.1.a

USGBC's LEED v4: Reference Guide for Building Design and Construction EQ Credit: Indoor Air Quality Assessment requires demonstration of formaldehyde levels less than 27 ppb.

01.1.b

USGBC's LEED v4: Reference Guide for Building Design and Construction EQ Credit: Indoor Air Quality Assessment requires demonstration of total VOC levels less than 500 μg/m³.

2

U.S. Environmental Protection Agency. National Ambient Air Quality Standards. 40 CFR Part 50. http://www.epa.gov/air/criteria.html. Revised October 2011. Updated December 14, 2012. Accessed September 16, 2014.

01.2.b

The EPA's 2012 NAAQS requre PM₂.₅ to be less than 12 μg/m³ for a primary annual mean, secondary annual mean of 15 μg/m³ and a 24-hour concentration of 35 μg/m³, averaged over three years .

01.2.a

The EPA's 2012 NAAQS require ambient air in cities to keep 8-hr average levels of carbon monoxide below 9 ppm and 1-hr averages below 35 ppm, not to be exceeded more than once per year.

01.4.a

The EPA's NAAQS set a 1-hour concentration level for carbon monoxide at 35 ppm, which is not to be exceeded more than once a year.

01.4.b

The EPA's NAAQS sets standards for PM₂.₅ at 12 μg/m³ for a primary annual mean, a secondary annual mean set at 15 μg/m³ and a 24-hour concentration set at 35 μg/m³, all averaged over three years.

01.4.c

The EPA's NAAQS for nitrogen dioxide set 100 ppb as the limit for the 98th percentile (averaged over three years) of hourly means.

3

World Health Organization. WHO Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide and Sulfur Dioxide. Geneva: World Health Organization; 2005: 9, 14.

01.2.c

The WHO's Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide, and Sulfur set 50 μg/m³ as a 24-hour mean concentration limit for PM₁₀.

01.2.d

The WHO's Air Quality Guidelines for Particulate Matter, Ozone, Nitrogen Dioxide, and Sulfur Dioxide recommend ozone limits at 100 μg/m³ 8-hour mean.

4

U.S. Environmental Protection Agency. A Citizen’s Guide To Radon: The Guide to Protecting Yourself And Your Family From Radon. http://www.epa.gov/radon/pdfs/citizensguide.pdf. Published May 2012. Accessed September 16, 2014.

01.3.a

The EPA's A Citizen's Guide to Radon recommends radon levels to be less than 4 pCi/L.

129

World Health Organization. Guidelines for Indoor Air Quality – Selected Pollutants. Geneva: World Health Organization; 2010: 141-142.

01.4.d

The WHO's indoor air quality guidelines set a short-term (30 minute) formaldehyde guideline of 0.1 mg/m³ [81 ppb] to prevent sensory irritation and also long-term health effects including cancer.