Air Cleaning Effects on Health and Perceived Air Quality

Supporting Information

Table 1. Technologies commonly used for particle air cleaning.

Technology Description & Principles Advantages Disadvantages Common Applications Related Health Data

Fibrous filters

Particles in air flowing through a porous fibrous media attach to the media and are removed from the air

Widely available technology

Simple, little to go wrong

Can have very high particle removal efficiency (depends on system design and particle size)

Requires a fan to move air through media

In general, more efficient filters have higher airflow resistance, increasing fan energy

Cost of regular changing of filter media every few months to year

Standalone units often noisy

Installed in heating, ventilating and air conditioning systems or in stand-alone portable air cleaners

Evidence of modest improvement in allergy and asthma health effects

Model predictions of substantial health benefits from use of filters to reduce indoor concentrations of particles from outdoor air

Electronic particle air cleaners with fans

Various designs, most systems electrically charge particles and collect them on electrostatically charged or grounded deposition surfaces

Widely available technology

Lower airflow resistance than fibrous filters, reducing fan energy

Can have high particle removal efficiency (depends on system design and particle size)

Requires a fan to move air through media

Can produce ozone as unintentional product

Regular maintenance needed

Higher first cost than fibrous filters

Decreasing particle removal efficiency during use

Standalone units often noisy

Installed in heating, ventilating and air conditioning systems or in stand-alone portable air cleaners

Minimal data available

The model predictions of health benefits from use of fibrous filters to reduce indoor concentrations of particles from outdoor air are also applicable to effective electronic particle air cleaners

Ion Generators

High voltages used to ionize air molecules creating ions that attach to and charge particles, charged particles deposit on indoor surfaces

No fan required, thus, energy efficient and quiet

Limited data on effectiveness in reducing airborne particles; some devices are clearly ineffective

Installed in occupied space

Minimal data available

Ultraviolet germicidal irradiation (UVGI)

UVGI damages the genetic material of microorganisms destroying their ability to replicate rendering them non-infectious

Requires no fans, quiet

Very low airflow resistance when in heating, ventilating, air conditioning systems

Potential high inactivation rates of microorganisms

Energy cost of ultraviolet lamps

Lamp replacement costs

Risks of human exposures to ultraviolet light

Can produce ozone as unintentional product

Reduced performance at high humidity

Installed near ceiling of rooms or in heating, ventilating, and air conditioning systems

Some data available indicating health benefits