In the environment surrounding the current pandemic situation, people everywhere are searching for answers to making our indoor spaces safer and healthier. This is quite evident in our schools where some of the widely recommended measures to curtain the spread of airborne illness can be difficult to implement.
Sometimes referred to as “cheap proven technologies” strategies such as implementing higher efficiency media filters, increasing ventilation and evening opening windows have been talked about to used in classrooms to reduce the likelihood of the spread airborne micro-organisms, virus and bacteria.
These methods all date back to the 1950’s. From that era, drum brakes in cars is also a cheap proven technology, as well as incandescent light bulbs. Essentially by using filtration as your air purification strategy, you are hoping to capture the viral particle on a tissue (the majority of filter material is supplied by Kimberly Clark, the maker of Kleenex).
The bigger issue is applying these methods in a real world school building setting. In a study done on New York City schools, only one third of schools had a mechanical ventilation or central heat and AC systems. Also from the same study, all but 18 percent of the schools studied, had no windows or windows that were broken and could not open. (Source: www.edweek.org). Many schools, especially in colder climates rely on unit ventilators or unitary systems that provide heat only and enough airflow from these systems to spread the heat throughout the classroom. For these schools filtration and / or ventilation upgrades are not possible without significant changes to the building with huge price tags and time when the building cannot be used due to construction.
Even in schools with central ventilation. Upgrading filters or increasing outside air ventilation is not as simple as that. Upgrading from a MERV (Minimum Efficiency Reporting Value) 8 filter to a MERV 13 filter as ASHRAE has recommended, will increase static pressure drop across the filter. This will result in lower airflow throughout the HVAC system. Since the HVAC system wasn’t designed for this airflow restriction from the higher rated filter, the space will be harder to heat and cool, the HVAC will run more often and for longer duration to satisfy the thermostat, fan horsepower demand will increase and the HVAC system overall will work much harder and be more prone to premature wear.
It gets worse, since the higher rated filter will capture more particles it will need to be replaced often or it will restrict airflow even more, as it gets loaded with dirt and gets thicker and thicker. AC coils may freeze and disable the HVAC system. Also reduced airflow will affect building pressurization making the space become under negative pressure, where uncontrolled air wants to be sucked into the building. This may result in problems in temperature and humidity controls and encourage mold and bacterial growth inside the building.
Also a MERFV 13 filter is tested to be 50% efficient to capture particles in the .3 to 1 um range. In relating to virus for example, a coronavirus particle is .12 um. These particles are too small to be captured by MERV 3 filters, only HEPA filters in MERV 17-20 range are rated for these sized particles.
Increasing outside air introduction or increased ventilation which can dilute indoor contaminants is also not easy to implement. In cases where central AC is not available the option would likely be opening windows and in many cases especially in cold weather climates, not an option. Even where there is central AC, these systems were designed around a load factor from the current outside air design, simply increasing that amount and load will require re-engineering the HVAC system to accommodate that load, tonnage capacity will need to increase, ducting, piping and even where the outside air introduced from will all need to be considered. All these measures, filtration and ventilation will significantly increase HVAC operating and overall energy costs.
For these many reasons AtmosAir and bi-polar ion technology has been used in countless schools with literally thousands of systems in place. The distinct advantage is AtmosAir will seamlessly integrate with HVAC systems and require no re-engineering of the mechanical systems to accommodate them, rather the AtmosAir technology adapts to the HVAC system. Also in the many schools where no central HVAC exists, AtmosAir has small devices that can integrate with classroom unit ventilators and other unitary systems to use the airflow from these devices to purify and spaces served by these unitary systems. AtmosAir can also be provided in self contained standalone units in cases where there is no supply air source at all.
Does BPI really work in school environments? Atmos Air started as an air testing company and testing and evaluating the performance of systems applied in the field under real world conditions has been a foundation for AtmosAir. These tests were done where no consideration for the testing was made and occupant activities and HVAC operation occurred as normal.
The elements of particulate matter (PM 10 PM 2.5) TVOC (Total Volatile Organic Compounds) and Spores were measured as an indicator of air cleanliness. Ozone was measured to determine if this by-product was generated by the operation of the AtmosAir systems. To add some context to the levels measured, see below some guidelines associated with these contaminant types:
PM 10 25 ug/m3 WHO (World Health Organization)
PM 2.5 50 ug/m3 WHO (World Health Organization)
TVOC 500 PPB USGBC (United States Green Building Council)
Spores N/A (There are no current guidelines as to Spore levels)
Ozone .01 PPM OSHA (Occupational Safety and Health Administration)
Also important to note that these studies were conducted so that the only controllable variable was the operation of the ionizer. In none of these studies was a contaminant purposely introduced into the environment to evoke a reaction by the air ionization process. What was present in the air was what naturally occurred at the time of the testing in a typical occupied school environment.
In conclusion, while media filtration and increased outside ventilation may be time honored methods to improve indoor air quality, they are often times very costly or impossible to implement in school classroom environments. Bi-polar ion technology such as AtmosAir has been in use in school systems for over 20 years for it’s ability to improve indoor air quality while not increasing operating costs and requiring costly HVAC re-engineering. These systems have a proven history of success in educational environments with studies showing measurable improvements in real world environments.