The US Centers for Disease Control and Prevention (CDC) has updated their ventilation guidelines to help prevent the indoor transmission of Covid-19 virus.
This is the first time that a federal agency has established a target for how many rooms and buildings need to be ventilated. The goal was set at five air changes an hour.
The updated recommendations were hailed by air quality experts.
It's a massive shift. This is something we haven't seen before. Joseph Allen, Director of Harvard Healthy Buildings Program, said, "We haven't had standards for ventilation that are health-based."
Allen says, although it is easy to only see the guidelines in the context Covid-19, they will also help with other airborne hazards such as wildfire smoke and allergens, or other infectious diseases like the flu.
The US declared a public health emergency on Covid-19 the day before the move. The CDC has long been reluctant to acknowledge that airborne transmission is a major factor in infectious disease transmission.
'I was pleasantly surprised that CDC added this guidance. It is ironic, I think, that the CDC has published a guide to help end the pandemic at a time when they are declaring the outbreak over.
In May 2020, Prather, along with her coauthors, published an article in Science explaining the airborne transmission of Covid-19. She and over 200 other scientists wrote a letter in the same year to the World Health Organization (WHO) and other public-health authorities, asking them to acknowledge airborne spread and develop guidelines to stop it.
Prather stated that if they had implemented and broadcast these changes from the start, there would never have been a Pandemic.
The new CDC guidelines were developed in conjunction with a standard by the American Society of Heating Refrigeration and Air Conditioning Engineers.
According to the CDC, better ventilation indoors can reduce viral particles in air and lower the risk of a person getting sick from inhaling them. The CDC says that improved ventilation can reduce the amount of viruses a person may inhale. This could lower their infectious dose and affect the severity of the infection.
The new guidelines offer detailed recommendations on how to improve indoor air quality. The strategies include opening windows to allow more outdoor air in and using fans to enhance the effect of opened windows.
The CDC also recommends that you clean your indoor air by using MERV-13 filters on your HVAC system. If they are equipped with high-efficiency particle air (HEPA), air cleaners and purifiers can be beneficial. According to the CDC, these devices are especially important in areas with high risk such as schools and medical offices. UV-based systems that kill germs can also be useful.
The CDC recommends at least five air exchanges per hour in order to reduce the amount of germs. The CDC states that a portable air purifier can provide the same amount of ventilation as long as the unit is sized appropriately for the area it will be used in.