(2021-02-14) This Is The Safest Indoor Space To Prevent The Spread Of Covid-19 According To A Mechanical Engineer

This is the safest indoor space to prevent the spread of COVID-19, according to a mechanical engineer. I am a professor of mechanical engineering at the University of Colorado Boulder. Much of my work has focused on how to control the transmission of airborne infectious diseases indoors, and I’ve been asked by my own university, my kids’ schools, and even the Alaska State Legislature for advice on how to make indoor spaces safe during this pandemic

The safest indoor space is one that constantly has lots of outside air replacing the stale air inside.

Environmental engineers like me quantify how much outside air is getting into a building using a measure called the air exchange rate.

Many buildings in the U.S., especially schools, do not meet recommended ventilation rates

So how do you know if the room you’re in has enough air exchange? It’s actually a pretty hard number to calculate. But there’s an easy-to-measure proxy that can help. Every time you exhale, you release CO2.

Outdoors, CO2 levels are just above 400 parts per million (ppm). A well-ventilated room will have around 800 ppm of CO2. Any higher than that and it is a sign the room might need more ventilation.

Last year, researchers in Taiwan reported on the effect of ventilation on a tuberculosis outbreak at Taipei University. Many of the rooms in the school were underventilated and had CO2 levels above 3,000 ppm. When engineers improved air circulation and got CO2 levels under 600 ppm, the outbreak completely stopped.

You can buy good CO2 meters for around $100 online; just make sure that they are accurate to within 50 ppm.

If you are in a room that can’t get enough outside air for dilution, consider an air cleaner, also commonly called air purifiers

The first thing to consider is how effective an air cleaner’s filter is. Your best option is a cleaner that uses a high-efficiency particulate air (HEPA) filter

The second thing to consider is how powerful the cleaner is. The bigger the room—or the more people in it—the more air needs to be cleaned. I worked with some colleagues at Harvard to put together a tool to help teachers and schools determine how powerful of an air cleaner you need for different classroom sizes.

the California Air Resources Board has a list of air cleaners that are certified as safe and effective, though not all of them use HEPA filters.

If you walk into a building and it feels hot, stuffy, and crowded, chances are that there is not enough ventilation. Turn around and leave.