Indoor air often contains invisible contaminants — including viruses, bacteria, mold spores, allergens, VOCs, and microscopic particulates. These pollutants can circulate through HVAC systems, linger in occupied rooms, and impact human health.
This guide explains what’s actually in the air and why it matters for indoor environments.
Pollen. Particles. Mold. Odors. Dirty air commonly contains mold spores that grow in damp places. It includes allergens like pet dander, dust mites, and pollen.
Virus. Bacteria. Mold Spores. Sick air contains a range of airborne pathogens which can cause viral, bacterial or fungal infections and illnesses.
VOCs. Particles. Toxic air contains chemicals released by buildings, furnishings, and cleaners. PM1.0 + PM2.5 from outdoor pollution, cooking, and wildfire smoke.
Microscopic pathogens that spread via airborne droplets and aerosol particles.
Key fact: Aerosolized viral particles can remain suspended and infectious for hours.
Key fact: Low indoor humidity and stagnant, unventilated air significantly increase bacterial survival rates and transmission.
Key fact: Spores lie dormant in dark, damp spaces and multiply rapidly once humidity rises.
Key fact: Allergens accumulate on soft surfaces and re-suspend into air when disturbed.
Volatile Organic Compounds
Volatile Organic Compounds (VOCs) are among the most common, and least understood, indoor air contaminants. Released from everyday products, furnishings, and building materials, these invisible gases can affect occupant health, comfort, productivity, and overall building performance.
VOCs are gases released from materials and chemicals.
Health effects:
Short-Term Exposure
Elevated VOC concentrations may contribute to:
• Eye, nose and throat irritation
• Headaches
• Fatigue
• Dizziness
• Nausea
• Skin irritation
• Increased asthma symptoms
Poor ventilation often magnifies these effects.
Long-Term Exposure
Prolonged VOC exposure has been associated with:
• Respiratory disease
• Liver and kidney damage
• Central nervous system impairment
• Cardiovascular disease
• Developmental and reproductive effects
• Increased cancer risk from compounds such as benzene and formaldehyde
Children, older adults and individuals with underlying respiratory conditions are particularly susceptible.
FACT: VOC levels indoors can be 2-10x higher than outdoors.
PM10
Course ParticlesCourse Particles,
affects upper respiratory tract
PM2.5
Fine particlesFine particles,
affect lower respiratory tract
PM1.0
Very fine particlesVery fine particles,
affects alveolus
PM0.1
Ultrafine particlesUltrafine particles,
affects blood/whole body
Understand the dynamic movement, recirculation, and accumulation of airborne pollutants in your facility.
Yes. Poor indoor air quality can cause immediate symptoms like headaches, fatigue, sinus irritation, and asthma flare-ups, while worsening respiratory infections. Prolonged exposure can lead to chronic health issues or Sick Building Syndrome (SBS), where occupants experience acute health effects linked directly to time spent in a specific building.
Indoor air pollution mainly consists of three categories: biological contaminants (bioaerosols like viruses, bacteria, mold, and allergens), volatile organic compounds (VOC gases off-gassed from cleaners, paints, and furnishings), and particulate matter (fine dust and PM2.5 suspended by airflow).
Pollutants enter through outdoor infiltration via open windows and building gaps, HVAC systems recirculating trapped air, and internal off-gassing from building materials and furnishings. Daily human activity—such as using chemical cleansers, cooking, tracking in dust, and occupant exhalation—also continually releases contaminants inside.
VOCs (Volatile Organic Compounds) are airborne chemical gases off-gassed from materials, paints, and cleaners. Biological contaminants are living or once-living matter, including viruses, bacteria, mold spores, pollen, and pet dander. While VOCs require gas-phase media or ventilation to dissipate, biological pollutants are physical particles controlled through particulate filtration and air purification.
Most airborne pollutants are invisible, but common indicators include unexplained headaches, fatigue, coughing, or heightened allergy flare-ups while indoors. Stale odors and rapid dust buildup are also clear red flags. Utilizing real-time IAQ monitoring or air testing helps identify these hidden contaminants before symptoms worsen.
Peak indoor air quality requires a layered defense strategy. Combating airborne pollutants effectively calls for combining fresh air ventilation to dilute concentrations, mechanical filtration to capture floating particles, and active technologies—such as soft bipolar ionization to agglomerate micro-particles and NanoStrike™ air disinfection to deactivate pathogens at the molecular level.
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