Coronavirus infections seem to occur mostly at short distances when persons interact, and also when touching surfaces with the virus. However, airborne transmission at longer distances is still a debated topic. There is not enough scientific evidence to confirm airborne transmission, but the risk is high enough to justify action. Considering this issue, shopping malls in New York state will be required to have filtering systems that can capture COVID-19.
ASHRAE recommends filters with a MERV rating of 13 or higher, in a scale from 1 to 16. MERV stands for Minimum Efficiency Reporting Value, a measurement scale that was first introduced by ASHRAE in 1987. High Efficiency Particulate Air filters (HEPA) are even more effective than MERV 16, and NASA has tested HEPA filters with particles as small as 0.01 microns (one micron is 1/1000 of a millimeter).
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Governor Andrew Cuomo announced that NY malls will be required to use filters with a high MERV rating or a HEPA rating. Otherwise, they will not be allowed to open. Businesses in general have been instructed to consider air filter upgrades, especially office buildings.
Air Filter Upgrade: Tips from Professional Engineers
Upgrading air filters may seem like a simple and straightforward procedure. However, simply replacing filters with the most efficient units available is not recommended by HVAC experts.
- Air filters add resistance to airflow, and more efficient filters have a greater resistance.
- When higher efficiency filters are installed, the ventilation system must produce more air pressure to reach the same airflow.
- If fans lack enough capacity for the new filters, the airflow will drop and the building may not get enough ventilation.
To ensure that shopping malls get enough ventilation after a filter upgrade, the best recommendation is contacting a qualified HVAC engineering firm. This way building owners can optimize their fan capacities and filter ratings, to achieve COVID-19 filtering at an optimal cost.
Property managers must be aware that air quality measures are not intended to replace the guidance from health authorities. In other words, social distancing and face masks are required, even if a building has excellent air quality.
Assuming that coronavirus is airborne is much smarter than assuming the opposite. Reaching a conclusion would require time and many experiments, and having too much protection is better than not having enough.
Additional Air Quality Measures for Malls in NY
Air filters that are capable of capturing coronavirus will be mandatory for NY malls. However, this can be combined with other measures recommended by ASHRAE, further reducing the risk of COVID-19. The ASHRAE recommendations also include a higher outdoor air ventilation, and adding ultraviolet germicidal irradiation systems (UVGI).
Many ventilation systems have smart controls that optimize airflow according to occupancy, and this concept is called demand controlled ventilation (DCV). However, during the coronavirus emergency and its aftermath, the best recommendation is disabling DCV and setting the outdoor airflow as high as possible.
With respect to UVGI, the highest germicidal effect is achieved with UV-C radiation, which has a wavelength below 280 nanometers. However, the UVGI systems must also be ozone-free, since ozone can severely irritate the respiratory system.