Prioritizing Ventilation During COVID-19, HEPA Filtration Recomended by WHO (World Health Organication)

Prioritizing Ventilation During COVID-19, HEPA Filtration Recomended by WHO (World Health Organication)

  1. School administrators and decision makers should purchase HEPA air filtration units to be placed in classrooms and common occupied spaces.

    Even if ventilation in a school already meets current building standards (many do not), additional air filtration from a portable device can help reduce the potential for SARS-CoV-2 transmission. Portable HEPA air filters are easy to use, HEPA filtration is a proven technology, and the units have the advantage of being always “on.” A quiet unit (or combination of smaller units) can increase the number of air changes by at least 3 to 5 times in an 800-square-foot classroom, can be purchased for about $500, and are less taxing on electrical systems than

    a portable air conditioner. Increasing the number of air changes per hour may substantially reduce aerosol transmission risks.

    1. School systems should use only proven technologies for improving indoor
      air quality: appropriate ventilation, HEPA filtration, or ultraviolet germicidal irradiation. They should not use chemical foggers or any “air cleaner” other than filtration and ultraviolet germicidal irradiation.

      School systems should not use unproven technologies such as ozone generators, ionization, plasma, and air disinfection with chemical foggers and sprays. The effect of these cleaning methods on children has not been tested and may be detrimental to their health. The primary aim for improving air quality should be to remove contaminants and impurities from the air and not to introduce new substances into the air.

      1. All students, teachers, and staff deserve healthy air, and many are not currently getting it. Proper ventilation will improve health and education. Ventilation systems should meet all applicable codes and standards, be regularly maintained, and be verified that the systems are functioning as designed.

        If schools only have natural ventilation, HVAC systems should be installed. Upgrades to facilities will take time but will improve ventilation in schools for the long term.

      Risks of SARS-CoV-2 spread in indoor environments

      There is extensive evidence that the SARS-CoV-2 virus can be spread through the air
      in a crowded indoor environment.
      44-46 For example, air samples from hospital rooms previously occupied by COVID-19 patients have yielded SARS-CoV-2 virus capable
      of infection in laboratory samples in low concentrations.
      47 A case study looking at a COVID-19 outbreak in a restaurant in Guangzhou, China, showed that secondary cases occurred along the line of airflow generated by indoor air conditioning systems, while individuals not in the line of airflow were not infected. This case supports aerosol transmission of SARS-CoV-2 virus due to poor ventilation.