The HVAC systems of large buildings typically filter air before it is distributed throughout a building, so consider upgrading HVAC filters as appropriate for your specific building and HVAC system (consult an HVAC professional). The variety and complexity of HVAC systems in large buildings requires professional interpretation of technical guidelines, such as those provided by ASHRAE and CDC. EPA, ASHRAE and CDC recommend upgrading air filters to the highest efficiency possible that is compatible with the system and checking the filter fit to minimize filter air bypass.
Consider using portable air cleaners to supplement increased HVAC system ventilation and filtration, especially in areas where adequate ventilation is difficult to achieve. Directing the airflow so that it does not blow directly from one person to another reduces the potential spread of droplets that may contain infectious viruses.
Air cleaning may be useful when used along with source control and ventilation, but it is not a substitute for either method. Source control involves removing or decreasing pollutants such as smoke, formaldehyde or particles with viruses. The use of air cleaners alone cannot ensure adequate air quality, particularly where significant pollutant sources are present and ventilation is insufficient. See ASHRAE and CDC for more information on air cleaning and filtration and other important engineering controls.
Some products sold as air cleaners intentionally generate ozone. These products are not safe to use when
people are present because ozone can irritate the airways. Do not use ozone generators in occupied spaces.
When used at concentrations that do not exceed public health standards, ozone applied to indoor air does not
effectively remove viruses, bacteria, mold, or other biological pollutants.