Indoor air quality is not one number
A room can have low particle levels but high carbon dioxide, or acceptable CO₂ while a strong odor source is present. Indoor air quality covers several pollutant categories, and each behaves differently. Useful monitoring and control starts by identifying what problem you actually have.
PM2.5
PM2.5 refers to particulate matter with an aerodynamic diameter of roughly 2.5 micrometres or smaller. Sources can include outdoor pollution, combustion, cooking and some indoor activities. Particle filtration is a key control method for suspended particulate matter that reaches the purifier.
VOCs
Volatile organic compounds are gases emitted by many materials and products. Depending on the compound and source, control may involve source removal, ventilation and sorbent media such as activated carbon. A particle filter alone is not designed to remove gases.
Carbon dioxide
In occupied indoor spaces, CO₂ is often used as an indicator related to ventilation and occupancy. Standard HEPA and carbon recirculating purifiers are not generally intended to remove occupant-generated CO₂. If CO₂ is the issue, fresh-air ventilation or another dedicated solution should be considered.
Humidity and biological growth
Excess moisture can contribute to condensation and microbial growth on building materials. A purifier does not repair leaks or replace moisture control. Address the water source, manage humidity and clean or remediate affected materials appropriately.
Match the tool to the pollutant
The most effective approach may combine several tools: source control, ventilation, particle filtration, gas adsorption and moisture management. Buying a purifier without defining the pollutant can lead to unrealistic expectations.
Related reading
Continue with our complete Indoor Air Knowledge Hub or read about PM2.5, VOCs and CO₂.