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

This evidence review finds that wearing masks reduces the transmission of COVID-19 by reducing the spread of infected respiratory particles, and recommends the adoption of public cloth mask wearing as an effective form of source control in conjunction with existing hygiene, distancing, and contact tracing strategies.

- Wearing masks reduces transmission of infected respiratory particles in both laboratory and clinical contexts. - Public mask wearing is most effective at reducing spread of the virus when compliance is high. - Cloth masks can be an effective form of source control in reducing disease spread. - Mask wearing by infectious people ("source control") can have benefits at the population level. - Public officials and governments should strongly encourage the use of widespread face masks in public.

This is from Emerging Infectious Diseases in 2020 at https://pubmed.ncbi.nlm.nih.gov/33431650/.

This systematic review of evidence suggests that wearing masks, wearing higher quality masks (respirators), and mask mandates generally reduced the transmission of SARS-CoV-2, although the quality of the studies analyzed was often poor and did not account for the highly transmissible Omicron variants.

- Testing, contact tracing, and isolation can substantially reduce the transmission of infection and improve public health outcomes. - The majority of studies suggest a considerable impact of testing, followed by isolation and treatment of detected individuals. - Contact tracing is a method of identifying potential secondary cases and can reduce the population-level growth rate or levels of infection. - There is a clear need for more robustly designed experimental studies to inform TTI design and quantify TTI impact across diverse populations, over different levels of compliance, over different time periods, and for different epidemiological characteristics. - More research is required to fully elucidate the epidemiological consequences of TTI under different scenarios, as well as the broader costs and benefits of different approaches to TTI.

This is from Royal Society Publishing in 2023 at https://royalsocietypublishing.org/doi/10.1098/rsta.2023.0133.

The evidence from a systematic review and meta-analyses suggests that medical face masks are effective in reducing respiratory transmissions, and universal mask-wearing should be applied-especially during the COVID-19 pandemic.

- Face masks are a common and practical control measure used globally to reduce the risk of infection and disease transmission. - Evidence was weak and inconsistent in the efficacy of face masks in preventing respiratory infections. - Participants with fit-tested N95 respirators were likely to have lesser infection risk. - Participants donning double-layered cloth masks were prone to infection. - Medical face masks (MFMs) were found to have protective benefits in reducing respiratory transmissions. - Universal mask-wearing should be applied, especially during the COVID-19 pandemic. - Cloth masks should not be used in outbreak hot spots and places where social distancing is impossible.

This is from IOP Publishing Ltd. in 2021 at https://pubmed.ncbi.nlm.nih.gov/34407516/.

EPA researchers are studying the effectiveness of various types of face masks and disinfection methods for personal protective equipment (PPE) against COVID-19, and their results will help healthcare professionals and the public make informed decisions regarding the most effective products to use.

- Face masks and other personal protective equipment (PPE) are important tools to protect the wearer and others against COVID-19. - Researchers are rigorously testing masks and other PPE in EPA’s laboratories in Chapel Hill and Research Triangle Park, North Carolina. - The researchers sought to determine whether alternatives to high-efficiency N95 masks reserved for health care workers could offer similar protection for hospital personnel in the event of shortages. - They found that the effectiveness of the masks varied widely: a three-layer knitted cotton mask blocked an average of 26.5 percent of particles in the chamber, while a washed, two-layer woven nylon mask with a filter insert and metal nose bridge blocked 79 percent of particles on average. - The team continues to explore mask performance with studies in progress on the effects of facial hair and face shape on mask fit. - EPA researchers wanted to know whether PPE could be disinfected and reused while providing the same level of protection for wearers. - Their preliminary results, published in an EPA Report, show that certain disinfection methods may work well on some types of PPE without damaging the material.

This is from Journal of American Medical Association in 2020 at https://jamanetwork.com/journals/jama/fullarticle/2771462. This is from Journal of American Medical Association in 2020 at https://jamanetwork.com/journals/jama/fullarticle/2768396. This is from EPA Report at https://www.epa.gov/coronavirus/evaluating-disinfection-methods-personal-protective-equipment-ppe-items-intended-0.

This article reviews the effectiveness of masks in preventing the spread of COVID-19, discussing the transmission modes of the virus and evaluating different types of masks for their inhalation protection and exhalation isolation capabilities. The main takeaway is that masks are an effective means of preventing virus transmission, but their effectiveness depends on factors such as the type of mask and environmental conditions.

- Masks can be effective in preventing the spread of COVID-19. - The effectiveness of masks depends on the type of mask and how it is used. - Masks can reduce the amount of virus that is released into the air. - Masks can also protect the wearer from inhaling the virus. - Other measures, such as social distancing and hand hygiene, are also important in preventing the spread of COVID-19.

This is from Med Devices Sens. in 2021 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883189/#.

Wearing masks, especially high-quality ones like surgical N95s, can help slow the spread of COVID-19, but they should be used in combination with other measures like vaccination and physical distancing, and the most protective masks should be reserved for health care professionals.

- Wearing a face mask slows how quickly the virus that causes COVID-19 spreads. - The CDC recommends wearing masks in specific places and situations. - The most protective mask that you'll wear regularly, fits well and is comfortable should be worn. - Respirators such as nonsurgical N95s give the most protection. KN95s and medical masks provide the next highest level of protection. Cloth masks provide less protection. - The most effective cloth masks are made of many layers of tightly woven fabric like cotton. - Your mask works best if it fits your face closely and has no gaps around the edges. - Proper use, storage and cleaning of masks also affects how well they protect you. - Don't put masks on anyone who has trouble breathing or is unconscious or otherwise unable to remove the mask without help. - Don't put masks on children under age 2. - Don't use face masks instead of physical distancing. - Experts do not recommend using face shields instead of masks. - After you're vaccinated, you can more safely return to doing activities that you might not have been able to do because of the pandemic. However, if you are in an area with a high number of people with COVID-19 in the hospital, the CDC recommends wearing a mask indoors in public.

This is from Mayo Clinic Staff in 2023 at https://www.mayoclinic.org/diseases-conditions/coronavirus/in-depth/coronavirus-mask/art-20485449.

The use of non-pharmaceutical interventions, such as social distancing and wearing face masks, was effective in reducing the spread of Covid-19 infections, according to a report from the Royal Society, which reviewed the evidence gathered during the pandemic for six groups of interventions and their effectiveness in reducing transmission.

- Lockdowns and face masks "unequivocally" reduced the spread of Covid-19. - Non-pharmaceutical interventions (NPIs) were effective in reducing transmission when applied in packages that combine a number of measures that complement one another. - Social distancing and lockdowns were the most effective category of NPIs. - Face masks and mask mandates were an effective approach to reduce infection. - Higher-quality respirator masks such as N95 masks were more effective than surgical-type masks. - Test, trace and isolate measures found reductions in Covid-19 deaths. - Establishing international protocols for conducting clinical trials and observational research on NPIs in advance of further pandemics is recommended.

This is from Philosophical Transactions of the Royal Society A in 2023 at https://royalsocietypublishing.org/toc/rsta/381/2200.

Mayo Clinic research has found that wearing masks and maintaining physical distance are effective ways to prevent the spread of COVID-19.

- Masks are effective in reducing droplet transmission and are critically important for protecting yourself and the people around you. - Disposable paper medical masks and two-layer cloth masks were effective in reducing droplet transmission and there was no difference between mask types in terms of how well they blocked aerosol particles emitted by the wearer. - Physical separation reduces the exposure of respiratory droplets and 6 feet separation reduces particle counts to near baseline levels. - Additional measures to reduce the risk of transmission include frequent hand washing, use of hand sanitizer before and after meals, after removing masks, and honoring posted room capacities in busy areas.

This is from Mayo Clinic News Network in 2023 at https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-research-confirms-critical-role-of-masks-in-preventing-covid-19-infection/.

This article explores different physical interventions that can be used to interrupt or reduce the spread of respiratory viruses, such as wearing masks, social distancing, and improving ventilation.

- Physical interventions can help reduce the spread of respiratory viruses. - Examples of physical interventions include wearing masks, social distancing, and hand hygiene. - These interventions can be effective in reducing the transmission of respiratory viruses in both community and healthcare settings. - It is important to use a combination of interventions to achieve the greatest impact.

This is from PMC in 2023 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9885521/

This study reviewed the effectiveness of physical interventions (such as masks, hand hygiene, and physical distancing) in preventing the spread of respiratory viruses and found that the evidence is limited and more research is needed. The use of medical/surgical masks in the community probably makes little or no difference to the outcome of influenza-like illness (ILI)/COVID-19 like illness compared to not wearing masks, while hand hygiene is likely to modestly reduce the burden of respiratory illness.

- Physical interventions, such as masks, hand hygiene, and quarantine, have been studied to interrupt or reduce the spread of acute respiratory viruses. - The effectiveness of face masks is uncertain, and the evidence is of low to moderate certainty. - Wearing masks in the community probably makes little or no difference to the outcome of influenza-like illness (ILI)/COVID-19 like illness compared to not wearing masks. - Hand hygiene is likely to modestly reduce the burden of respiratory illness. - There is a need for large, well-designed randomized controlled trials addressing the effectiveness of many of these interventions in multiple settings and populations, as well as the impact of adherence on effectiveness, especially in those most at risk of acute respiratory infections.

This is from Cochrane Database of Systematic Reviews in 2023 at https://pubmed.ncbi.nlm.nih.gov/36715243/.

The effectiveness of physical interventions, such as hand hygiene, masks, and N95/P2 respirators, in reducing the spread of respiratory viruses is uncertain due to a high risk of bias in studies and variations in outcome measurements, but hand hygiene programs may be beneficial in reducing the burden of respiratory illness.

- Face masks may not have a substantial effect on influenza transmission. - Eye protection and physical distancing measures are believed to be effective but have limited evidence. - Hand hygiene may have mixed and inconclusive results in preventing the transmission of respiratory viruses. - The evidence for non-drug interventions is based on small and underpowered trials with poor reporting of methods and lack of blinding.

This is from Cochrane Database of Systematic Reviews in 2023 at https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6/full.