The U.S. Environmental Protection Agency (EPA) has released information on how increasing ventilation, alongside best practices recommended by the CDC, can protect people from COVID-19. Increasing ventilation, the amount of outdoor air coming indoors, is an important approach to lowering the concentrations of indoor air pollutants or contaminants including any viruses that may be in the air. As most commercial buildings have heating, ventilation, and air conditioning (HVAC) systems with filters on them, the EPA suggests that professionals who operate commercial buildings should consult guidance by ASHRAE (formerly known as American Society of Heating, Refrigerating and Air-Conditioning Engineers), and other professional and government organizations for information on ventilation and air filtration. If increasing ventilation with all or mostly outside air is not possible, the effective rate of ventilation per person can also be increased by limiting the number of people present in the building in general, or in specific rooms. The guidance also states that increasing ventilation when cleaning or disinfecting is helpful in reducing exposure to cleaning and disinfection products and byproducts. Increasing ventilation can also reduce risks from particles resuspended during cleaning, including those potentially carrying COVID-19 (or other contaminants).