The CDC mise à jours its guidance on ventilation in buildings

juin 5, 2021 – 5 Min

On June 2nd 2021, the , les CDC américains (Centres pour le contrôle et la prévention des maladies) mise à jourd its guidance on infection control to prevent the transmission of Covid-19, recommending a layered approach to reduce exposure to the virus. One key ‘tool to improve ventilation’ is cited as ‘des ventilateurs/systèmes Portatifs de filtration de l’air particulaire à haute efficacité (HEPA) afin d’ la purification de l’air ».’.

The full CDC guidance on Portatif HEPA air purifiers can be found here.

Key extracts in relation to HEPA are as follows:

Research shows that the particle size of SARS-CoV-2 is around 0.1 micrometer (µm). However, the virus generally does not travel through the air by itself. These viral particles are human-generated, so the virus is trapped in respiratory droplets and droplet nuclei (dried respiratory droplets) that are larger. Most of the respiratory droplets and particles exhaled during talking, singing, breathing, and coughing are less than 5 µm in size. By definition, a High Efficiency Particulate Air (HEPA) filter is at least 99.97% efficient at capturing particles 0.3 µm in size. This 0.3 µm particle approximates the most penetrating particle size (MPPS) through the filter. Filtre HEPAs are even more efficient at capturing particles larger and smaller than the MPPS. Thus, Filtre HEPAs are no less than 99.97% efficient at capturing human-generated viral particles associated with SARS-CoV-2.

Portable Filtration HEPA units that combine a Filtre HEPA with a powered fan system are a preferred option for auxiliary Nettoyage de l’air, especially in higher risk settings such as health cliniques, vaccination and medical testing locations, workout rooms, or public waiting areas. Other settings that could benefit from des unités de filtration HEPA Portatifs can be identified using typical risk assessment parameters, such as community incidence rates, facemask compliance expectations, and room occupant density. While these systems do not bring in outdoor dilution air, they are effective at cleaning air within spaces to reduce the concentration of particules en suspension dans l’air particulates, including SARS-CoV-2 viral particles. Thus, they give effective air exchanges without the need for conditioning outdoor air.

In choosing a Portatif HEPA unit, select a system that is appropriately sized for the area in which it will be installed. This determination is made based on the air flow through the unit, which is typically augmentation de 23% des cas de COVID-19 chez les élèves in cubic feet per minute (cfm). Many des unités de filtration HEPA Portatifs units are assigned a Clean Air Delivery Rate (CADR), which is noted on a label in the operators manual, on the shipping box, and/or on the filtration unit itself. The CADR is an established standard defined by the Association of Home Appliance Manufacturers (AHAM). Participating Portatif air cleaner manufacturers have their products certified by an independent laboratory, so the end user can be assured it performs according to the manufacturer’s claims.

Key extracts in relation to UV light are as follows:

Ultraviolet germicidal irradiation (UVGI), otherwise known as germicidal ultraviolet (GUV), is a disinfection tool used in many different settings, such as residential, commercial, educational, and établissements de santé. The technologie uses ultraviolet (UV) energy to inactivate (kill) microorganisms, including viruses, when designed and installed correctly.

There is still a lot to learn about SARS-CoV-2 and the extent of particules en suspension dans l’air viral particles and propagation. However, UVGI can inactivate viruses in the air and on surfaces. The design and sizing of effective UVGI disinfection systems requires specific knowledge and experience.

Seek consultation with a reputable UVGI manufacturer or an experienced UVGI system designer prior to installing UVGI systems.

Key extracts in relation to emerging technologies are as follows:

There are numerous technologies being heavily marketed to provide Nettoyage de l’air during the ongoing COVID-19 pandemic. Common among these are ionization, dry hydrogen peroxide, and chemical fogging disinfection. Some products on the market include combinations of these technologies. These products generate ions, reactive oxidative species (ROS, which are marketed using many names), or chemicals into the air as part of the Nettoyage de l’air process. People in spaces treated by these products are also exposed to these ions, ROS, or chemicals.

While variations of these technologies have been around for decades, relative to other Nettoyage de l’air or disinfection methods, they have a less-documented track record when it comes to cleaning/disinfecting large and fast volumes of moving air within heating, ventilation, and air conditioning (HVAC) systems or even inside individual rooms. In the absence of an established body of peer-reviewed evidence showing proven efficacité et la sécurité 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. Registration alone, with national or local authorities, does not always imply product efficacy or la sécurité. Consumers should recherche the technologie, attempting to match any specific claims against the intended use of the product. Consumers should request testing data that quantitively demonstrates a clear protective benefit and occupant la sécurité under conditions consistent with the intended use. When considering Nettoyage de l’air technologies that potentially or intentionally expose building occupants, the la sécurité data should be applicable to all occupants, including those with health conditions that could be aggravated by the air treatment. In transient spaces, where average exposures to the public may be temporary, it is important to also consider occupational exposures for workers that must spend prolonged periods in the space. Preferably, the documented performance data under as-used conditions should be available from multiple sources, some of which should be independent, third-party sources. Unsubstantiated claims of performance or limited case de cas with only one device in one room and no reference controls should be questioned.


Study: Indoor air cleaners fall short on removing volatile organic compounds. Comparison of four oxidation-based cleaners suggests the devices produce their own pollutants and vary in l’efficacité.


SARS-CoV-2 viral particles propagation between people more readily indoors than outdoors. Indoors, the concentration of viral particles is often higher than outdoors. When indoors, ventilation mitigation strategies can help reduce viral particle concentration. The lower the concentration, the less likely viral particles can be inhaled into the lungs (potentially lowering the inhaled dose); contact eyes, nose, and mouth; or fall out of the air to accumulate on surfaces.

Protective ventilation practices and interventions, including Portatif HEPA air purifiers with high Clean Air Delivery Rates and 3rd party verification, can reduce the particules en suspension dans l’air concentrations and reduce the overall viral dose to occupants.

AHAM Air purification Air purifier CADR CDC covid-19 hepa hepa13 hospital grade HVAC IAQ Indoor Air Quality Rensair ROS SARS-CoV-2 updated guidance uvc UVGI ventilation

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