The Air Quality Index (AQI) is a standardized measurement used to indicate how clean or polluted the air is, and what associated health effects might be of concern.
Here’s how it works:
🔹Lower AQI = Better air quality
🔹Higher AQI = More pollution and greater health risks
What it means for health:
🔹0–50: Good
🔹51–100: Moderate
🔹101–150: Unhealthy for Sensitive Groups
🔹151–200: Unhealthy
🔹201–300: Very Unhealthy
🔹301–500: Hazardous
What is Particulate Matter?
AQI typically includes measurements of Particulate Matter (also called Particle pollution)—a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.
Particle pollution includes:
🔹PM10: Inhalable particles with diameters generally 10 micrometers and smaller
🔹PM2.5: Fine inhalable particles with diameters generally 2.5 micrometers and smaller
How small is 2.5 micrometers?
Think about a single strand of human hair. The average human hair is about 70 micrometers in diameter—making it roughly 30 times larger than the largest PM2.5 particle.
What Kinds of Harmful Effects Can Particulate Matter Cause?
Exposure to both PM2.5 and PM10 is associated with a range of adverse health effects.
For PM2.5:
Short-term exposure (up to 24 hours) has been linked to:
🔹Premature mortality
🔹Increased hospital admissions (heart and lung issues)
🔹Acute and chronic bronchitis
🔹Asthma attacks
🔹Emergency room visits
🔹Respiratory symptoms
🔹Restricted activity days
These health effects are more commonly reported in infants, children, and older adults with preexisting heart or lung diseases.
For PM10:
Short-term exposure has been primarily linked to the worsening of respiratory conditions such as:
🔹Asthma
🔹Chronic Obstructive Pulmonary Disease (COPD)
This can lead to increased hospitalization and emergency department visits.
How Can I Reduce My Exposure to PM?
You can protect yourself by:
🔹Monitoring air quality alerts
🔹Limiting outdoor activity when PM levels are high
🔹Using indoor air purifiers or filtration systems
Particle pollution in the WELL v2 Building Standard (Air Concept)
The WELL Air Concept in v2 Building Standard, developed by the International WELL Building Institute (IWBI), emphasizes the importance of indoor air quality in promoting human health and well-being. One key component of this standard is the control and monitoring of particulate matter (PM)—specifically PM2.5 and PM10.
According to WELL Air Concept A05 (Enhanced Air Quality):
1 point:
🔹PM2.5: 12 µg/m³ or lower
🔹PM10: 30 µg/m³ or lower
2 points:
🔹PM2.5: 10 µg/m³ or lower
🔹PM10: 20 µg/m³ or lower
What is Carbon dioxide (CO₂)?
CO₂ is a colorless, odorless, and non-flammable gas that naturally occurs in the atmosphere. CO₂ is produced by body metabolism and is a normal component of exhaled breath.
CO₂ is often measured in indoor environments as a quick indicator of whether additional ventilation is required. Because CO₂ is a known indoor pollutant, excessive levels can negatively affect employee performance, productivity, and overall health.
We tend to measure CO₂ in ppm (parts per million) because it is the easiest way to quantify a substance that is colorless, odorless, and invisible to the human eye.
Regular monitoring of CO₂ levels helps to:
🔹Ensure proper ventilation
🔹Reduce airborne illness transmission risks
🔹Improve productivity and well-being
🔹Maintain regulatory compliance for workplace safety
What does exposure to high CO₂ levels feel like?
Here are some common symptoms of being in an environment with elevated CO₂ levels:
🔹Stale air
🔹Difficulty breathing
🔹Drowsiness and fatigue
🔹Headaches
🔹Poor concentration and cognitive function
🔹Increased heart rate
🔹Nausea and dizziness
The WELL Building Standard v2 addresses carbon dioxide (CO₂) as a critical indicator of indoor air quality (IAQ) and ventilation effectiveness.
According to WELL Building Standard A06 (Enhanced Ventilation Design), the following requirements apply for naturally ventilated buildings:
Implement an engineered natural ventilation system that maintains CO₂ levels in the breathing zone of all regularly occupied spaces below the specified thresholds at maximum intended occupancies:
1 Point:
🔹Threshold: 900 ppm OR 500 ppm above outdoor levels
2 Points:
🔹Threshold: 750 ppm OR 350 ppm above outdoor levels
In summary, maintaining indoor CO₂ levels within the acceptable range helps ensure good indoor air quality as well as the well-being and comfort of occupants.
What is Volatile Organic Compounds (VOCs)?
VOCs are a group of compounds with high vapor pressure and low water solubility. In other words, these substances easily evaporate into the air and do not readily dissolve in water. Examples of VOCs include Benzene, Ethylene glycol, Formaldehyde, Methylene chloride. Tetrachloroethylene, and Toluene.
Common Sources of VOCs are household and commercial products, such as:
🔹Paints, paint strippers, and other solvents
🔹Wood preservatives
🔹Aerosol sprays
🔹Cleansers and disinfectants
🔹Moth repellents and air fresheners
🔹Stored fuels and automotive products
🔹Dry-cleaned clothing
🔹Pesticides
🔹Building materials and furnishings
🔹Office equipment
🔹Nail polish and nail polish removers
What is Total Volatile Organic Compounds (TVOC)?
TVOC refers to the total concentration of all VOCs present in the air. The TVOC level is the sum of all VOC levels that impact indoor air quality. TVOC is typically measured in micrograms per cubic meter (µg/m³).
Potential Health Effects of TVOCs:
🔹Eye, nose, and throat irritation
🔹Fatigue
🔹Allergic skin reactions (e.g., from toluene)
🔹Headaches, dizziness, nausea, and loss of coordination
🔹Damage to the liver, kidneys, and central nervous system (with long-term, high-dose exposure)
🔹Some VOCs, like formaldehyde, are known carcinogens; others are suspected to cause cancer in humans
🔹Conjunctival (eye) irritation
🔹Difficulty breathing (dyspnea)
🔹Decreased serum cholinesterase levels
WELL Building Standard (Air Concept A01: Air Quality)
Under the WELL v2™ framework, which emphasizes performance-based design to support human health and wellness, To meet WELL criteria for continuous air quality monitoring in occupiable spaces, the following threshold must be achieved: TVOC: ≤ 500 µg/m³
What is Formaldehyde (HCHO / CH₂O / H₂CO)?
HCHO is one of the most hazardous components among total volatile organic compounds (TVOCs). This colorless gas is commonly found in building materials and household products. Fortunately, formaldehyde has a distinct odor — it can be recognized by its strong, pungent smell.
Prolonged exposure to HCHO can damage mucous membranes, irritate the respiratory system, and is classified as a potential human carcinogen.
Due to its severe health impacts and frequent presence in indoor environments, air quality monitors often track formaldehyde separately from other VOCs.
According to the WELL Building Standard v2, under the Air Concept (A05: Enhanced Air Quality) for all spaces, the following threshold must be met in occupiable areas: Formaldehyde: 9 µg/m³ or lower
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