United States Environmental Protection Agency, Indoor Air and Coronavirus (COVID-19),
www.epa.gov/coronavirus/...

United States Environmental Protection Agency, EPA Researchers Study Aerosol Transport and Mitigation
Measures to Reduce COVID-19 Transmission, Nov. 2020, www.epa.gov/sciencematte...

Some of these CDC links were very likely moved before 2025.

Interesting, I notice some of these EPA links still work:

Centers for Disease Control and Prevention, Underlying Medical Conditions Associated with Higher Risk for
Severe COVID-19: Information for Healthcare Providers, Oct. 2021, www.cdc.gov/coronavirus/...

Centers for Disease Control and Prevention, COVID-19 People with Certain Medical Conditions, Updated Feb.
2021, www.cdc.gov/coronavirus/...

Centers for Disease Control and Prevention, Scientific Brief: SARS-CoV-2 Transmission, May 2021,
www.cdc.gov/coronavirus/...

CDC Morbidity and Mortality Weekly Report, Effectiveness of Face Mask or Respirator Use in Indoor Public
Settings for Prevention of SARS-CoV-2 Infection, Feb 11, 2022 / 71(6);212–216,
www.cdc.gov/mmwr/volumes...

Centers for Disease Control and Prevention, Scientific Brief: Community Use of Masks to Control the Spread of
SARS-CoV-2, Updated Dec. 2021, www.cdc.gov/coronavirus/...

CDC Morbidity and Mortality Weekly Report, Efficacy of Portable Air Cleaners and Masking for Reducing
Indoor Exposure to Simulated Exhaled SARS-CoV-2 Aerosols, July 9, 2021 / 70(27);972–976,
www.cdc.gov/mmwr/volumes...