2.1 Air Quality Thresholds (A01) & Smoke-Free Environments (A02)

2.1 Air Quality Thresholds (A01) & Smoke-Free Environments (A02)

Core Exam Takeaway: Features A01 Air Quality and A02 Smoke-Free Environment are two of the Air concept's four preconditions (the others are A03 Ventilation Design and A04 Construction Pollution Management). Memorize A01's numbers exactly: PM2.5 ≤ 15 µg/m³, PM10 ≤ 50 µg/m³, CO ≤ 10 mg/m³ [9 ppm], ozone ≤ 100 µg/m³ [51 ppb], benzene ≤ 10 µg/m³, formaldehyde ≤ 50 µg/m³, toluene ≤ 300 µg/m³, radon ≤ 0.15 Bq/L [4 pCi/L] — and A02's 25 ft (7.5 m) buffer.

The Air concept aims to achieve high indoor air quality across a building's lifetime through source elimination or reduction, active and passive building design and operation strategies, and human behavior interventions. Air is also the most heavily weighted knowledge domain on the WELL AP exam at 11 scored questions, so the fourteen Air features (A01–A14) repay precise study.

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The Physiological Imperative

People spend approximately 90% of their time in enclosed spaces, and indoor concentrations of many pollutants routinely exceed outdoor levels. WELL's own framing is blunt: radon exposure is the second leading cause of lung cancer after tobacco use, and exposure to VOCs, ozone, particulate matter and carbon monoxide raises the risk of respiratory and cardiovascular disease.

+-----------------------------------------------------------------------------+
|                        INDOOR AIR POLLUTION CASCADE                         |
|                                                                             |
|   Inhalation --> Deep Alveolar Penetration --> Capillary Translocation      |
|                          |                             |                    |
|                          v                             v                    |
|               Pulmonary Inflammation          Systemic Oxidative Stress     |
|                          |                             |                    |
|                          v                             v                    |
|             Asthma, COPD, Reduced FEV1        Atherosclerosis, Thrombosis   |
+-----------------------------------------------------------------------------+

Acute and Chronic Health Manifestations

1. Respiratory degradation. Inhaled particulates and chemical vapors irritate the nasopharyngeal tract, provoke bronchial spasm and drive allergic sensitization. Long-term exposure accelerates Chronic Obstructive Pulmonary Disease (COPD), contributes to pediatric asthma development and produces permanent decrements in Forced Expiratory Volume ($FEV_1$).
2. Cardiovascular morbidity. Fine particulate matter ($PM_{2.5}$) is small enough to bypass the ciliated mucus escalator of the upper airway. On reaching the alveoli, particles cross the alveolar–capillary membrane into systemic circulation, triggering vascular inflammation, arterial plaque progression, elevated blood pressure and increased risk of myocardial infarction and stroke.
3. Sick Building Syndrome (SBS) vs. Building-Related Illness (BRI).
   • SBS: acute, non-specific symptoms — headache, burning or itching eyes, throat irritation, lethargy, dizziness, dry skin — experienced inside a building and resolving after departure, with no isolable pathogen. WELL cites a U.S. study estimating that sick leave attributable to insufficient fresh air is roughly 35% of total absenteeism.
   • BRI: clinically diagnosable conditions attributable to specific building contaminants — Legionnaires' disease from aerosolized Legionella pneumophila, Pontiac fever, and hypersensitivity pneumonitis from aerosolized fungal spores or actinomycetes.
4. Cognitive impairment. Elevated indoor $CO_2$ and TVOC measurably degrade higher-order cognition. WELL notes that ventilation rates below 21 cfm (10 L/s) per person are associated with negative air-quality perception and adverse health outcomes, and that sick-building-syndrome risk falls significantly when $CO_2$ stays under about 800 ppm.

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Feature A01: Air Quality — Precondition

A01 provides "a basic level of indoor air quality," using thresholds set by public health authorities such as the WHO and U.S. EPA. It has five parts. Parts 1–3 apply in occupiable spaces; Part 4 applies to regularly occupied spaces at or below grade; Part 5 requires annual monitoring.

A01 Part 1 — Particulate Matter (three options, and two of them cap your level)

Projects consult the WHO Global Urban Ambient Air Pollution Database to establish outdoor levels.

[!IMPORTANT] The level cap is the highest-yield fact in A01. A project in Delhi or Beijing that takes Option 3 cannot exceed Silver even with 95 points. Watch for exam scenarios that hand you a big point total and a polluted-region option.

A01 Part 2 — Organic Gases (two options)

[!WARNING] Candidates frequently import WELL v1's formaldehyde number (27 ppb / 33 µg/m³) or a generic "TVOC ≤ 500" as the A01 requirement. Under WELL v2, formaldehyde is 50 µg/m³ in the laboratory option, and 500 µg/m³ TVOC is the monitoring option's threshold, not an additional lab limit.

A01 Part 3 — Inorganic Gases

Note what is not here: nitrogen dioxide is not an A01 threshold. $NO_2 \le 40\ \mu\text{g/m}^3$ [21 ppb] belongs to A05 Enhanced Air Quality, Part 3 — an optimization.

A01 Part 4 — Radon

For regularly occupied spaces at or below grade, one of the following:

• Radon $\le 0.15\ \text{Bq/L}$ [$4\ \text{pCi/L}$], tested by a professional demonstrated not to have a conflict of interest with the WELL project, at one test per 25,000 ft² (2,300 m²) of at-or-below-grade regularly occupied space; or
• All those spaces meet A03 Part 1 Option 1 (the mechanical ventilation pathway) instead. Effective mechanical ventilation is itself an accepted radon control.

A01 Part 5 — Monitor Air Parameters

For all spaces except dwelling units: the Parts 1–3 pollutants are monitored in regularly occupied spaces at intervals no longer than once per year, results submitted annually through the WELL digital platform, with sampling points per the Performance Verification Guidebook. Projects may monitor total VOCs instead of the individual VOCs in Part 2. If a WELL Performance Testing Agent takes the measurements in compliance with the guidebook, the annual results may be averaged and used for recertification.

WELL Core scope for A01

Meet A01's requirements in non-leased spaces, provided that area comprises at least 2.5% of the total project area; otherwise supplement with enough leased space to reach 2.5%.

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Feature A02: Smoke-Free Environment — Precondition

WELL's premise is that there is no safe and acceptable level of cigarette smoke exposure, so the only protective measure is a 100% smoke-free environment. Burning cigarettes form over 7,000 compounds, of which at least 69 are known carcinogens, and WELL notes that smokers' average life expectancy is about 10 years shorter than non-smokers'. Thirdhand smoke — residual chemicals clinging to walls, furniture, clothing, bedding and carpet long after smoking — is explicitly within scope.

           [ OUTDOOR SMOKING BUFFER ZONE: 25 FEET (7.5 METERS) ]

                  Outdoor Air Intake     Operable Window        Main Entryway
                        [ === ]              [ | ]                 [   ]
                           |                   |                     |
   <-----------------------+-------------------+---------------------+----------------------->
   |                       |                   |                     |                      |
[25 ft / 7.5 m]     [25 ft / 7.5 m]     [25 ft / 7.5 m]       [25 ft / 7.5 m]        [25 ft / 7.5 m]
   |                       |                   |                     |                      |
   v                       v                   v                     v                      v
====================== SMOKING & VAPING PROHIBITED (+ SIGNAGE) ==============================
   PLUS: banned on ALL decks, patios, balconies, rooftops and other occupiable
   outdoor areas ABOVE ground level -- regardless of distance from openings.
   IF smoking is allowed anywhere outdoors within the boundary, hazard signs
   must be placed along walkways NOT MORE THAN 100 ft (30 m) apart.

A02 Part 1 — Prohibit Indoor Smoking

Smoking and the use of e-cigarettes is prohibited in interior spaces within the project boundary. No exceptions exist for ventilated indoor smoking rooms, lounges or private suites. WELL Core guidance: meet this in the whole building.

A02 Part 2 — Prohibit Outdoor Smoking

Smoking and e-cigarette use is prohibited, with signage present to clearly communicate the ban:

• (a) Outdoors at ground level within 25 ft (7.5 m) — or the maximum extent allowable by local codes — of all entrances, operable windows and building air intakes. Where outdoor areas within the boundary do allow smoking, signs describing the hazards of smoking must be placed along walkways not more than 100 ft (30 m) apart.
• (b) On decks, patios, balconies, rooftops and other occupiable outdoor areas above ground level — an unconditional ban that does not depend on the 25 ft measurement.

[!TIP] Two A02 details separate prepared candidates: the "or the maximum extent allowable by local codes" escape clause (a jurisdiction that forbids a 25 ft private buffer does not disqualify the project), and the 100 ft (30 m) signage spacing rule that applies only when smoking is permitted somewhere outdoors inside the boundary.