Indoor Air Quality

Prior to the COVID pandemic, room air exchanges ranged from 3 to 5 times an hour, depending on location, such as a school, hospital, public building, or at home.  There has been a great deal of discussion, and some research, since then to determine what a healthy turn over rate should be, some regulating bodies suggest levels of 10 or more.  To accomplish this higher turn over level with traditional HVAC systems requires either increasing the fan speed, increasing the amount of fresh air brought in, or, most likely, a combination of the two.  While the solution sounds simple, there are significant issues with these approaches.  The outside temperature and humidity will impact the systems performance, and higher fan speeds will require higher energy needs.  To address these low efficiency and high cost issues, researchers have recognized that additional local treatment can be used to effectively increase the air turnover rate.  These include filters, ionizers, ozone, chemicals, and ultraviolet (UV) light.

Indoor Air Treatment

Each treatment option comes with its benefits and drawbacks.  Below is a short review of several options.

Ozone

Pros – Ozone has been demonstrated to be an effective disinfectant, able to cleanse an airspace to the level required, just add enough ozone.

Cons – Exposure to ozone may cause headaches, coughing, dry throat, shortness of breath, a heavy feeling in chest, and fluid in the lungs. Higher levels of exposure can lead to more severe symptoms. Chronic exposure may lead to asthma.  As a result, it is only truly effective in unoccupied spaces.  In addition, the generation of ozone is energy intensive, resulting in higher energy costs.

Ionization

Pros - Ions, especially bipolar ionization, has been shown to be an effective air disinfectant.  These devices can be installed in a room or a HVAC duct system.

Cons – The EPA regards bipolar ionization as an emerging technology, and therefore unsure of long-term effects that may result from its use.  Concerns include the generation of ozone and other by-products that may have result in negative health effects.  The technology also requires a significant amount of energy to generate the ions.

Chemical Treatment

Pros – This is a very broad category and there are numerous chemical formulations that have been proven to be effective at disinfecting air.  This is generally accomplished by disrupting the cell wall or the capsid of a virus.

Cons – In general, these chemicals have not been evaluated for their long -term effects on humans and other materials they may come in contact with.  The use of chemicals is most often recommended for unoccupied spaces, but the effects of any residue are generally not fully studied.

UV treatment

UV light technology has a long history of effective disinfection in water applications.  The method by which UV performs the disinfection is that the light penetrates the cell and either causes the DNA to crosslink or destroying proteins within the cell, both of which interfere with the cells ability to replicate.  There are currently two wavelengths of UV lamps that are used in air treatment, 222 nm and 254 nm lamps.

UV 222 nm Pros – Recent research has shown that the 222 nm light does not pose a threat to either skin or eyes, so the equipment can be used to illuminate a room.

Cons – 222 nm lamps do generate wavelengths that produce ozone, so care must be taken to filter out these wavelengths.  To achieve full room coverage lamps must be arranged with overlapping outputs to obtain the coverage needed for disinfection.  Current designs of these lamps are relatively inefficient, so the number of lamps and the power required can be significant.  Since these are mounted on walls or in the ceiling, installation must be permitted and performed by a licensed contractor.  The EPA also considers this an emerging technology, with unknown long-term effects.  The UV light may reduce the life of fabrics and plastics material it is exposed to.

UV 254 nm Pros – The lamps have long been used to disinfect the upper air space of rooms.  Installed properly the technology disinfects the room air above the occupied zone and relies on room air circulation to bring the air into the disinfection space.  Numerous studies have shown that this is an effective disinfection process.  One or more UV monitors must be located within the space to determine if a sufficient amount of UV is being produced.

Cons – Care must be used during the installation of the devices to prevent exposure in the occupied space.  As a result, permitting and the use of a licensed contractor is required for installation.  Since the process relies on good circulation between the occupied lower zone and the upper room zone, this process must be evaluated to each installation.  As with the 222 nm lamps, one or more UV monitors are required to establish proper dosing.

How the M600 Works

The M600 addresses many of the short comings of the technologies described above, while still providing the most effective air treatment for an occupied space.  This fully portable air treatment system that relies primarily on 254 nm UV lamps, but also incorporates an input filter and MERV-13 output filters.  The air is sucked into the unit through a MERV-8 input filter at the rear of the unit.  The fan then pushes the air through a duct system containing two 254 nm UV lamps as well as the ReFlex UV dose boosting system, and then the air is pushed out of the unit through the MERV-13 filters.

The M600 will circulate air in a 30 x 30 x 10 room every fifteen minutes.  The effectiveness will depend on the position of the unit and the furniture within the room.  The unit is also very portable, so that it can be relocated quickly as needed.

There is a control panel on the rear of the unit that provides a power switch and a display panel providing the system status.  The display will alert the user as to when the filters and lamps need to be changed. The system is equipped with a UV intensity meter to ensure proper dosage is provided within the unit.

The system is designed to be quiet enough to operate while the room is occupied, like for a classroom or a conference room.  The system operates at 54 dB when pushing 600 CFM, about the equivalent of a bathroom vent fan.  The fan speed can be increased to provide additional treatment when rooms are unoccupied.  This setting can be used to rapidly clear a room after use.

Efficacy and Validation

The M600 has been proven effective through two university studies, one at Arizona State University and the second a Purdue University, both studies used T1 as a surrogate for the Sars-CoV-2 virus.  T1 has been shown to have a slightly more conservative response to UV light.  The ASU testing was performed to show an initial capability of the M600 and demonstrated a 3-log reduction in the T1 surrogate.

The testing at Purdue was more extensive and utilized a room that was demonstrated to be fully mixed.  In this test room simulated a condition where there was an active shedder present, so there was a continuous feed of the T1 surrogate injected into the room.  This test showed that after a steady state of virus had been achieved and the unit turned on, it took about 8 minutes to result in a 1-log reduction.

The M600 has also met all of the fire and EMC safety criteria through TUV Sud, so that it meets all building code requirements.

Operation

The installation of the M600 is as simple as installing a toaster, the unit is removed from its packaging, moved to the preferred location in the room (the unit has casters), plugged into a standard electric outlet, and then turned on.  It may take up to fifteen minutes for the UV lamps to achieve full strength.  The are no requirement for permits or contractors for installation.

The M600 is ideal for hospital waiting rooms, classrooms, conference rooms, spas, gyms, restaurants, beauty parlors, or any occupied location where an active shedder may be present.

Efficacy and Validation

The M600 has been proven effective through two university studies, one at Arizona State University and the second a Purdue University, both studies used T1 as a surrogate for the Sars-CoV-2 virus. T1 has been shown to have a slightly more conservative response to UV light. The ASU testing was performed to show an initial capability of the M600 and demonstrated a 3-log reduction in the T1 surrogate.

The testing at Purdue was more extensive and utilized a room that was demonstrated to be fully mixed and operated under timeframes that assured starting and ending equilibrium conditions were reached. This testing also simulated conditions approximating the presence of an “active shedder” of virus, by continuously injecting T1 surrogate into the room. This test showed that after a steady state of virus had been achieved and the unit turned on, it took about 8 minutes to result in a 1-log reduction of the total surrogate circulating in the room.

The M600 has also met all of the fire and EMC safety criteria through TUV Sud, so that it meets all building code requirements.

As previously mentioned, the M600 contains the UV light within its chamber. The measured UV at the output filters is well below the exposure limits set forth by OSHA. The measured values are close to 0 mW/cm2 within an couple of inches of the surface.

Please contact us with you application requirements at www.info@UVBreeze.com.