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Was the technology evaluated for potential adverse health effects or occupational exposures? A MERV 13 filter and a box fan? • Consider portable room air cleaners with HEPA filters. This Standard is what led to the creation of the minimum efficiency reporting value, or MERV. CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. He added that on days when the UV lights were deployed in hospitals, "the air was about 80 percent less infectious.". The Covid-19 diameter is around 0.1 micron. Other settings that could benefit from portable HEPA filtration can be identified using typical risk assessment parameters, such as community incidence rates, facemask compliance expectations and room occupant density. MERV values range from 1 to 16 and higher MERV values correspond to more efficient filters. Even if the virus is captured, it would likely survive for some time. By definition, a High Efficiency Particulate Air (HEPA) filter is at least 99.97% efficient at capturing particles 0.3 µm in size. Consider operating these systems, even when the specific space is not occupied, to increase overall ventilation within the occupied building. Using ductwork and placing the HEPA system strategically in the space can help provide desired clean-to-less-clean airflow patterns where needed. Increase airflow to occupied spaces when possible. Thus, the recommended filters are significantly more efficient at capturing particles of concern than a typical MERV 8 filter, which is only around 20% efficient in the 1 µm to 3 µm size range and is not rated for capture efficiency of the smaller 0.3 µm to 1.0 µm particles. The table provides estimates of the time required for airborne-contaminant removal based upon the room’s ventilation rate, measured in air changes per hour (ACH) and the desired removal efficiency (99% or 99.9%). Accordin… While these systems do not bring in outdoor dilution air, they are very effective at cleaning air within spaces to reduce the concentration of airborne particulates, including SARS-CoV-2 viral particles. Of all the unknowns still surrounding the transmission of the coronavirus, one thing is for sure: Being indoors with lots of people in cramped conditions is a major no-no. However, GUV can inactivate viruses in the air and on surfaces*. See Example 2 for more information, including an example of the calculations. In addition to buildings, ventilation considerations are also important when you have multiple persons within vehicles, including public transportation (buses, subways, trains, school buses, carpools, and rideshares). In conclusion, adding the portable HEPA unit increased the effective ventilation rate and improved room air mixing, resulting in an 80% reduction in time for the room to be cleared of potentially-infectious airborne particles. Examples of “less-clean” spaces might include spaces that contain known/suspect infectious persons or spaces where a known activity has increased likelihood of generating infectious airborne particles. Directional Airflow is a protective ventilation concept where air movement flows in a clean-to-less-clean direction. Operate these systems any time these spaces are occupied. *Note: CDC’s recommendation for primary surface disinfection in occupied environments is to follow the CDC/EPA guidance for surface disinfection. Ensuring appropriate outdoor air and ventilation rates is a practical step building owners and managers can take to ensure good indoor air quality. Removal times will be longer in rooms or areas with imperfect mixing or air stagnation.” Appropriate use of Table B.1 to establish clearance times from any space requires multiplying the time in the table by a mixing factor (k) that ranges between 1 and 10. Use fans to increase the effectiveness of open windows. A lower density but still powerful MERV filter could be a good alternative. It can take several minutes for particles 10 µm in size to settle, while particles 5 µm and smaller may not settle for hours or even days. The design and sizing of effective GUV disinfection systems requires specific knowledge and experience. Consider using ultraviolet germicidal irradiation (UVGI) as a supplement to help inactivate SARS-CoV-2, especially if options for increasing room ventilation are limited. MERV stands for the Minimum Efficiency Reporting Value of a filter. The performance is based on particles that are 0.3-10 micron in diameter. Using the mixing factor of 3, the estimated wait time for 99% reduction of airborne contaminants in the room is 3 x 23 = 69 minutes. In specific settings, specialized local control ventilation interventions that establish the desired airflow directions can also be used (see the NIOSH Ventilated Headboard). Saving Lives, Protecting People. To safely achieve this, fan placement is important and will vary based on room configuration. Portable HEPA filtration units that combine a HEPA filter with a powered fan system are a great option for auxiliary air cleaning, especially in higher risk settings such as health clinics, medical testing locations, workout rooms, or public waiting areas. Now, calculate the air changes per hour: ACH = [Q x 60] / (room volume) = (72 cfm x 60) / (12’ x 10’ x 9’) = 4320/1080 = 4.0 ACH. The COVID-19 virus, like most viruses particles, is an extremely tiny biological organism. While MERV ratings reflect a filter's ability to trap both microscopic and macroscopic particles, MPR ratings only grade a filter on its capacity to remove particles from 0.3 to 1 microns. Can COVID-19 be transmitted through HVAC (ventilation) systems? Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website. Inspect filter housing and racks to ensure appropriate filter fit and check for ways to minimize filter bypass. Select from 1", 2', and 4" depths. There is still a lot to learn about SARS-CoV-2, the virus that causes COVID-19, and the possibility of airborne viral particles and spread. When indoors, ventilation mitigation strategies help to offset the absence of natural wind and reduce the concentration of viral particles in the indoor air. There is no obvious answer to this question given unknowns about the nature of SARS-CoV-2 containing particles and droplets. Here are four steps for improving your company's air quality and more. It is suggested to have the fan run continuously and change filters every 30 days. Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 µm in size. This type of air filter can theoretically remove at least 99.97% of dust, pollen, mold, bacteria, and any airborne particles with a size of 0.3 microns (µm). While the list of tools is intended to be universally applicable across indoor environments, applying them to different building types, occupancies, and activities under environmental and seasonal changes can be challenging. However, in the era of Covid-19, it is time to take all of the tools out of the toolbox. The MERV provides a measure of the “filter efficiency” over the range of particle sizes prescribed in the test procedure. Depending on the size of the HEPA fan/filter units and how the facility in which they are being used is configured, multiple small portable HEPA units deployed to high risk areas may be more useful than one large HEPA unit serving a combined space. Most home furnace filters have a MERV Rating around 8, which will take out pollen and dust. • Keep systems running longer hours, if possible 24/7, to enhance the two actions above. HEPA fan systems can be used as stand-alone units, or many larger units allow flexible ductwork to be attached to the air inlet and/or outlet (note that larger ducted units don’t fall under the “room air cleaner” description and may not have a CADR rating). And he said we should "absolutely" look at the MERV 13 filters for our homes. It starts with getting a good air filter. Avoid placing fans in a way that could potentially cause contaminated air to flow directly from one person over another. What Merv rating should I use? [See the question on Portable HEPA Filtration to learn more about them and their application in protective air cleaning]. That sobering fact has put industries that rely on in-person and high-density interactions--from wedding and concert venues to hotels and restaurants--in incredible distress. It is definitely not a new idea. Unsubstantiated claims of performance or limited case studies with only one device in one room and no reference controls should be questioned. Creation of the directional airflow can also be done actively, through the use of fans exhausting through open windows, strategic placement of ductwork attached to portable HEPA filtration units, or dedicated exhaust systems (installed or portable) that generate a desired airflow by exhausting air out of windows, doorways, or through temporary ducts. Many New Jersey homeowners ask us about MERV ratings, especially when it comes to choosing between MERV 8 and MERV 11 air filters. The technology uses ultraviolet (UV) energy to inactivate (kill) microorganisms, including viruses, when designed and installed correctly. MERV filters are not effective at filtering microbes and viruses until they are rated at 17 or better. Check filters to ensure they are within their service life and appropriately installed. One research group reported that the use of a new air-sampling method allowed them to find viable viral particles within a COVID-19 patient’s hospital roomexternal iconexternal icon with good ventilation, filtration and ultraviolet (UV) disinfection (at distances as far as 16 feet from the patient). While it may not be necessary to apply every consideration to be protective, implementing multiple mitigation strategies is recommended, if possible, to improve effectiveness. Our filters are available in three grades – Merv 8, Merv 11, and Merv 13. Increased ACH generally leads to reductions in k, although k can also be reduced by the use of a fan in the space, which does not have an impact on ACH. Through his research, he found that UV was "quite safe." While an HVAC system handles a building's heating, cooling, and ventilation, the system's filter can be limited in terms of air purification; it might catch big particles but not smaller air pollutants. For reference, a typical dust particle is between .2 and 8 microns, while pollen starts at … However, this may be difficult to do in cold, hot, or humid weather. Our Merv 8 standard capacity pleated filters are offered in ASHRAE 52.1 and 52.2 (MERV) ratings and … But a MERV 8 filter is not fine enough to take out PM2.5 or viruses; for that, you need at least MERV … What is a HEPA filter and why would I want to use a portable HEPA air cleaner? An air purifier can combat other causes of respiratory problems and improve the overall air quality in your home, but a standard HEPA filter can’t capture and destroy something as small as a virus. Cost estimates per room for the listed ventilation interventions in cost. Efficiencies for MERV 15 and MERV 16 filters are even higher. Available in MERV 6, MERV 8, MERV 11, and MERV 13 ratings. This factor represents how well the ventilation system mixes and dilutes the concentration of airborne particles within the room. In that case, the time identified from Table B.1 should be multiplied by 3 in order to determine the actual clearance time prior to re-entry. In addition to ventilation, the layered approach includes efforts to improve social distancing, wearing face masks, and hand hygiene. Using Table B.1 the perfect mixing wait time based on 4 ACH and a 99% reduction of airborne particles is 69 minutes. Also, the addition of an air cleaning device (e.g., a portable HEPA filtration unit) within the same room will reduce the wait time. "This is going to be a crisis," says one manufacturer of MERV-13 filters, which can prevent the coronavirus from moving through building climate control systems. Be sure to seek consultation with a reputable GUV manufacturer or an experienced GUV system designer prior to installing GUV systems. When used along with other best practices recommended by CDC and others, filtration can be part of a plan to protect people indoors. employees are also reluctant to return to work, potentially costing owners more in energy bills. "Filtration or air cleaning is not magic," says Siegel. • Improve central10 air filtration to the MERV-1311 or the highest compatible with the filter rack, and seal edges of the filter12 to limit bypass. CDC does not provide recommendations for, or against, any manufacturer or product. A PECO filter mightmake a difference, but only in a limited way. It ensures reliable and consistent testing of air filter performance. Healthcare facilities have ventilation requirements in place to help prevent and control infectious diseases that are associated with healthcare environments. Ultimately, wait times can be reduced by increasing ACH, reducing k, or a combination of both. Dilution ventilation and particle filtration are commonly used to remove these smaller particles from the air. While many of these in-person businesses are waiting out the pandemic and staying closed temporarily, others are taking steps to mitigate the spread of the virus, which they hope will inspire enough people to come back inside to keep their businesses afloat. CDC recommends using the highest efficiency ventilation filters possible, without having detrimental effects on overall HVAC system performance. The flow rate from the air cleaning device can be added to Q determined above, which will increase the overall ACH in the room. Prior to a filtration upgrade, the specific filter under consideration should be investigated for its pressure drop ratings at the flow rate(s) of intended use and the potential impacts of that pressure drop evaluated against the capabilities of the existing HVAC system. The company also offers a more robust purifier intended for use in medical spaces. The COVID-19 Virus is 2.5 times smaller than the 0.3 micron cutoff. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. Implementing multiple tools at the same time is consistent with CDC mitigation strategies and increases overall effectiveness. Decrease occupancy in areas where outdoor ventilation cannot be increased. For more information, see the CDC Guidelines for Environmental Infection Control in Health-Care Facilities. MERV, otherwise known as Minimum Efficiency Reporting Value, is a measurement scale that rates the effectiveness of filters at trapping airborne particles. Our Merv 8 filter eliminates allergens such as dust, pollen, mold spores, and pet dander. While cleaning your air is important for any in-person business, it should not be your only defense against the coronavirus, says Jeffrey Siegel, a civil engineering professor at the University of Toronto. How much time is required to reduce the airborne particle concentration by 99 percent? The filter's density can be problematic, however. The air movement created by the air cleaning device can also decrease the value of k.  Together, the increased ACH and decreased k can help substantially reduce wait times. A True HEPA filter will certainly capture some COVID-19 particles. If the room in which the air cleaner will be used is taller than 8 feet, choose an air cleaner with a proportionally higher CADR than that based simply on square footage. Have performance results been published in a scientific or medical journal? Using Table B.1, the perfect mixing wait time based on 12 ACH and a 99% reduction of airborne particles is 23 minutes. ASHRAE, has similar guidance, however, they recommend a minimum filtration efficiency target of MERV 13, provided there are not substantial negative impacts on the HVAC system performance and occupant comfort. Another factor driving the popularity of MERV 8 filters is that they are inexpensive and easily serviced. So you need to … To help protect against COVID-19 virus, ASHRAE changed its recommendation from MERV 8 filters to MERV 13+. To receive email updates about COVID-19, enter your email address: Centers for Disease Control and Prevention. These viral particles are human-generated, so the virus is trapped in respiratory droplets and droplet nuclei (dried respiratory droplets) that are larger. Four types of residential HVAC filters were investigated in this study. "No one should be installing filtration and forgetting about everything else," he says. In homes and buildings where the HVAC fan operation can be controlled at the thermostat, set the fan to the “on” position instead of “auto,” which will operate the fan continuously, even when heating or air-conditioning is not required. Most commercial and residential HVAC systems have a MERV 6 or 8 filter, which takes care of the basic pollen, dust, dust mites, mold and bacteria. The added air movement within the room improves overall mixing, so assign k = 3. Thus, the recommended filters are significantly more efficient at capturing particles of concern than a typical MERV 8 filter, which is only around 20% efficient in the 1 µm to 3 µm size range and is not rated for capture efficiency of the smaller 0.3 µm to 1.0 µm particles. The cost of retrofitting an HVAC system to a MERV 13 filter depends on the size and age of your current system, with smaller jobs clocking in at 25 cents per cubic foot per minute, says Gabriel Domenikos, director of operations at Airlogix, a commercial and industrial air conditioning and refrigeration company based in New York City. There are numerous devices being heavily marketed to provide air cleaning during the ongoing COVID-19 pandemic. Scientific developments in filter design have reduced the amount of the increased pressure drop and its resulting impact on HVAC operations, but not all filters have adopted the newer technology. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. Some of the most common are ionization and/or dry hydrogen peroxide devices. While airflows within a particular space may help spread disease among people in that space, there is no evidence to date that viable virus has been transmitted through an HVAC system to result in disease transmission to people in other spaces served by the same system. However, outside of a few unique applications, HEPA filters are rarely used in central HVAC systems. A MERV 8 air filter is efficient at trapping a majority of indoor particulates that could debilitate those with asthma and allergies, or even cause long-term respiratory problems. Research has shown that the particle size of the COVID-19 virus is around 0.1 µm (micrometer). This ventilation concept is applied to areas where the “clean” environment requires a higher level of protection and/or where the “less-clean” environment has a higher risk of containing airborne contaminants (activities or occupancy by individuals with a higher risk of being infectious). CDC twenty four seven. A MERV 11 filter only needs to stop 20% of particles in the 0.3 to 1.0 micron (three to ten times bigger than a COVID-19 particle), a MERV 12 only needs to stop 35% of particles under 0.3 micron, and a MERV 13 only needs to stop half. Standard 52.2 establishes a testing protocol. While MERV ratings reflect a filter's ability to trap both microscopic and macroscopic particles, MPR ratings only grade a filter on its capacity to remove particles from 0.3 to 1 microns. Generate clean-to-less-clean air movement by re-evaluating the positioning of supply and exhaust air diffusers and/or dampers (especially in higher risk areas). There may be some implications for HVAC systems associated with these findings, but it is too early to conclude that with certainty. In choosing a portable HEPA unit, you want to select a system that is appropriately sized for the area in which it is installed. It will be up to the building owner/operator (obtaining expert consultation as needed) to identify which tools are appropriate for each building throughout the year. HEPA filters are even more efficient at capturing particles larger and smaller than the MPPS. However, in the absence of an established body of peer-reviewed evidence showing proven efficacy and safety under as-used conditions, the technologies are still considered by many to be “emerging.” As with all emerging technologies, consumers are encouraged to exercise caution and to do their homework. SARS-CoV-2 viral particles spread between people more readily indoors than outdoors. Consider ventilation system upgrades or improvements and other steps to increase the delivery of clean air and dilute potential contaminants. On their own pandemic hit North America last February, building IAQ has come into an entirely different focus out. 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