Air cleaners and HVAC filters can help reduce airborne contaminants, including viruses, but are not a substitute for other practices like social distancing and mask wearing; it's important to choose an air cleaner that is effective in filtering out small airborne particles and to avoid air cleaners that intentionally generate ozone or that do not meet state regulations or industry standards for ozone generation, and while DIY air cleaners can be effective, they should be constructed carefully and used only when other air filtration options are not available.

- Portable air cleaners and HVAC filters can help reduce airborne contaminants, including viruses. - Air cleaning or filtration alone is not enough to protect people from COVID-19. - When used along with other best practices, filtration can be part of a plan to reduce the potential for airborne transmission of COVID-19 indoors. - To select an air cleaner that effectively filters viruses from the air, choose a unit that is the right size for the space, has a high CADR for smoke, is designated a HEPA unit, or specifically indicates that it filters particles in the 0.1-1 um size range. - Do not use air cleaners that intentionally generate ozone in occupied spaces or that do not meet state regulations or industry standards for ozone generation. - DIY air cleaners can be of comparable effectiveness to commercial air cleaners in reducing airborne particles, but their performance does vary based on the design selected and the quality of materials and assembly. - EPA does not recommend the routine use of DIY air cleaners as a permanent alternative to products of known performance.

This is from EPA in 2023 at https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19

Air filtration using high-efficiency particle arrestance (HEPA) filters is an effective intervention in managing the spread of COVID-19 by removing aerosol particles containing SARS-CoV-2 virions from the air, but it is important to understand the principles of air filtration and the interactions between aerosol particles and filter materials to determine the best practices for its use.

- Stationary and portable HEPA filtration systems are recommended for use in healthcare settings by the United States Centers for Disease Control and Prevention and the World Health Organization. - National and international standards govern the minimum filtration efficiency characteristics of HEPA filters. - Antiviral properties can be imparted to the filter materials, but once aerosol particles are collected on the filter fibers, virtually none detach and pass through the filter during or after proper use. - Breathing polluted air is strongly associated with adverse effects on respiratory and cardiovascular function. - Interventions based on air filtration using adequate equipment should be widely implemented both to reduce the spread of SARS-CoV-2 via the aerosol phase and to improve the health status and outcomes for people exposed to and infected with COVID-19.

This is from Epih in 2020 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7644931/#.

This article characterizes the performance of a do-it-yourself box fan air filter as a lower-cost alternative to standalone air filtration systems and demonstrates its effectiveness in reducing suspended particle concentrations in indoor environments.

- DIY box fan air filters can effectively reduce indoor air pollution. - HEPA filters are more effective than MERV 13/14 filters. - Portable air cleaners can eliminate airborne SARS-CoV-2. - Indoor air pollution can be reduced with air filtration units. - Filtration of airborne microorganisms can be modeled and predicted.

This is from Aerosol Science and Technology in 2022 at https://www.tandfonline.com/doi/full/10.1080/02786826.2022.2054674.

Proper ventilation, air filtration, germicidal ultraviolet lights and air quality monitoring are recommended for public spaces to prevent COVID-19 infections from spreading through inhaling fine aerosol particles that can hang in the air for hours, with little data favoring droplets or contact with contaminated surfaces as the primary way the virus is spread.

- Indoor air ought to be regulated for infection control, much like food and water are, air experts propose in the May 14 Science. - Cleansing the air is mostly a matter of proper ventilation and filtration. - Increasing ventilation in one room may carry infectious viruses into connected rooms through HVAC vents. - Experts recommend filtering air through materials that can trap airborne particles containing the virus. - Germicidal ultraviolet light may zap the virus and kill it in the air. - Not all UV lights are created equal, though.

This is from Science News in 2023 at https://www.sciencenews.org/article/coronavirus-covid-air-spread-indoor-clean-ventilation-filtration.

A homemade air filter made from a box fan, cardboard, tape, and furnace filters, known as the Corsi-Rosenthal box, may be an effective and affordable way to improve indoor air quality by removing pollutants and viruses like COVID-19, according to early research.

- A good filtration system can help protect you and your family from allergens, indoor pollutants like smoke, and viruses like COVID-19. - Richard Corsi, PhD, of the University of California-Davis and Jim Rosenthal, CEO of Tex-Air Filters, have created a type of homemade air filter that costs less than a third of the price of many HEPA devices. - Some early research suggests these DIY air cleaners, made from cardboard, tape, furnace filters, and a box fan, might be more effective in some ways than HEPA purifiers. - Experts say they could offer a simple solution to improve air quality in our homes, classrooms, and workplaces, which aren’t always well-ventilated. - One study looked at how well Corsi-Rosenthal boxes removed chemicals from the air in an academic building at Brown University. In the 2-month period when the boxes were used, concentrations of certain PFAS (chemicals found in cleaning products and textiles) went down by 40%-60%. At the same time, concentrations of phthalates (from personal-care products and building materials) went down 30%-60%. - According to the Environmental Protection Agency (EPA), the best ways to improve indoor air quality are to remove sources of pollutants (like cleaning chemicals or cigarette smoke) and ventilate your space with outdoor air.

This is from WebMD in 2023 at https://www.webmd.com/allergies/corsi-rosenthal-box.

Air filtration, avoidance of recirculation of air, enhanced particle filtration by suitable air filters, and air disinfection can control COVID-19 infection transmission in indoor spaces, and the use of HEPA filters, UVC light, and natural ventilation are effective methods for reducing the spread of the virus.

- Effective ventilation, avoidance of recirculation of air, enhanced particle filtration by suitable air filters and air disinfection can control COVID-19 transmission. - Opening windows can increase natural ventilation and dilute indoor air, reducing infection spread. - Indoor air purifiers with high efficiency particulate air (HEPA) filters can filter contaminated indoor air, but must be replaced regularly. - Far-UVC light is recommended for single rooms without air conditioning, while a combination of HEPA filter and UVC light can reduce bacterial and virus load significantly in air-conditioned rooms. - The supply or outdoor air should be filtered by a filter and then mixed with the recirculated air and supplied to the room through the HEPA filters. - The ASHRAE recommends HVAC systems with a minimum efficiency of Minimum Efficiency Reporting Value-13 (MERV-13) to filter even very small particles.

This is from BMC Infectious Diseases in 2021 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8234247/.

The Corsi-Rosenthal box is a cost-effective DIY air filter made from MERV13 furnace filters and a box fan that can help clear indoor air from airborne virus particles, wildfire smoke, pollen, dust, and more.

- DIY box fan filters can help clean indoor air from airborne virus particles, wildfire smoke, pollen, dust, and more. - The Corsi-Rosenthal box is a cost-effective and efficient air cleaner. - The box fan filter can be built using a box fan and MERV13 filters. - There are various modifications and designs available for the box fan filter. - The box fan filter has been used in classrooms and homes to improve indoor air quality.

This is from Clean Air Crew in 2023 at https://cleanaircrew.org/box-fan-filters/.

Using a relatively low-cost "do-it-yourself" air filter (Corsi-Rosenthal Box) can reduce indoor air concentrations of certain chemicals, including PFAS and phthalates, which are commonly found in office building materials and products, but may result in slightly higher sound levels.

- A low-cost "do-it-yourself" air filter (Corsi-Rosenthal Box; CR Box) reduces exposure to several lower-volatility phthalates and sulfonated PFAS previously found in office building materials and products. - Concentrations of seven PFAS and five phthalates were 28-62% lower while CR Boxes were deployed. - Concentrations of five PFAS and one phthalate increased 23-44% during the intervention period, but the 95% CI of most of these estimates included the null. - Daytime sound levels increased 5.0 dB when CR Boxes were operating.

This is from Environmental Science & Technology in 2022 at https://pubmed.ncbi.nlm.nih.gov/36562547/.

HEPA filters can effectively remove infectious SARS-CoV-2 from the air, providing insights into the proper use and performance of air filtration technologies to prevent the spread of COVID-19.

- HEPA filters can effectively remove infectious SARS-CoV-2 from the air. - HEPA filters with an antiviral agent coating have a capture ratio comparable to conventional HEPA filters. - Proper use of HEPA-filtered air cleaners can help prevent the spread of COVID-19.

This is from the journal "Nature Communications" in 2021 at https://pubmed.ncbi.nlm.nih.gov/35947419/.

Corsi-Rosenthal boxes, a DIY indoor air filter, were found to be effective in reducing a wide range of volatile and semi-volatile organic contaminants, according to a study that employed non-targeted and suspect screening analysis using high resolution mass spectrometry.

- Corsi-Rosenthal boxes, a do-it-yourself indoor air filter, may have potential co-benefits of reducing indoor air contaminant levels. - Do-it-yourself Corsi-Rosenthal boxes are an effective means for improving indoor air quality by reducing a wide range of volatile and semi-volatile organic contaminants.

This is from The Author(s), under exclusive licence to Springer Nature America, Inc. in 2023 at https://pubmed.ncbi.nlm.nih.gov/37414869/.

A study has shown that biocide treated air filters can effectively kill bacteria, fungi and viruses, including SARS-CoV-2, and maintain their structure and filtration function while also being durable and maintaining antimicrobial activity throughout their operational lifetime, making them a potential tool to prevent airborne transmission of respiratory diseases in public spaces such as public transport.

- Antimicrobial and anti-viral coated air filters can be effective in preventing the spread of airborne pathogens. - The study was funded by the Wellcome Trust ISSF award, Royal Academy of Engineering Award, and an MRC Proximity to Discovery award. - The authors acknowledge financial support for this work by the Engineering and Physical Sciences Research Council (EPSRC) Grant codes: EP/P029868/1 and EP/S021434/1. - The article is licensed under a Creative Commons Attribution 4.0 International License. - The study was conducted by researchers from the University of Birmingham, University of Nottingham, and NitroPep Ltd.

This is from Nature in 2022 at https://www.nature.com/articles/s41598-022-06579-9

Increasing ventilation and filtration in indoor spaces can help reduce the risk of airborne transmission of infectious agents, including SARS-CoV-2, and should be considered as a fundamental part of risk reduction strategies.

- Increasing air changes per hour and air filtration can help reduce the risk of airborne transmission of respiratory infectious diseases like SARS-CoV-2. - Higher ventilation and enhanced filtration are often overlooked but fundamental parts of risk reduction strategies that could have benefits beyond the current pandemic.

This is from JAMA in 2021 at https://jamanetwork.com/journals/jama/fullarticle/2779062.

The Corsi-Rosenthal box, a simple and inexpensive air purifier made from furnace filters and a box fan, has been effective in reducing airborne transmission of Covid-19 and is an example of how grassroots innovation and citizen engineering can have a significant impact in times of crisis.

- The Corsi-Rosenthal box is a simple, inexpensive, and effective air purifier that has been used to fight Covid-19. - It consists of furnace filters and a box fan, and can be assembled with minimal technical expertise and $60 to $90 in materials. - Corsi-Rosenthal boxes are more effective than placing a single filter in front of a box fan, and can supplement existing ventilation systems in shared spaces. - The Corsi-Rosenthal box was developed through a grassroots effort that drew on the knowledge and efforts of a wide range of contributors from different backgrounds and organizations. - Grassroots innovation has promise, but can also face challenges such as lack of technological sophistication and resources, rules and regulations, and sustaining effort.

This is from Smithsonian Magazine in 2022 at https://www.smithsonianmag.com/innovation/homemade-air-purifier-thats-been-saving-lives-during-covid-19-pandemic-180979681/

Proper ventilation, including increasing outdoor air delivery, filtration, and air cleaning, can help reduce the concentration of viral particles in indoor spaces and lower the risk of exposure to COVID-19.

- Indoor air movement and dilution of viral particles through mechanical or nonmechanical means can reduce the airborne viral concentrations and the overall viral exposure to occupants. - Ventilation system upgrades or improvements can increase the delivery of clean air and dilute potential contaminants. - Implementing multiple building-level mitigation strategies at the same time is consistent with CDC’s layered approach and will increase overall effectiveness of ventilation interventions. - Ventilation interventions can reduce the spread of disease, but they will not eliminate risk completely. - Improving air circulation and cleanliness can help reduce viral particle concentration. - Aim for 5 or more air changes per hour (ACH) of clean air to help reduce the number of germs in the air. - The ventilation interventions listed above come with a range of initial costs and operating costs.

This is from CDC in 2023 at https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation.html.