The following is a series of quick tips that I've gathered from various sources and experts.* I hope this page is easy to understand and implement so that you may regain some control over YOUR surroundings and reduce anxiety regarding health safety. I've listed the tips in order of affordability.
FULL DISCLOSURE: I'm not an expert! I am a parent and employer who's responsible for others. I am a licensed architect and former engineer with 2 engineering degrees - in other words, a very curious science nerd. I closely follow the latest updates from the experts themselves and want to help get their messages out, especially when it comes to space-related ways we can prevent the spread. In short, I have had to understand and assess the pandemic holistically, including politically, socially and scientifically. I will revise and update this post when appropriate so I invite any and all feedback. Here goes:
Air Quality –> "Aerosol Science"
COVID-19 travels thru the air like tiny balls. If you can improve or "clean" the air quality, you can reduce the risk of infection. There's moisture (water) in the air. Like in rush hour traffic, the more moisture is in the air, the harder it is for a virus particle to travel. The quicker a virus particle slows down, the quicker it falls to ground and avoids infecting others.
The virus also travels in different size clumps, like motorcycles vs cars vs vans vs trucks on a highway. Some viral particles are encapsulated like a car or van and some break open like a convertible with its top down; some are active and others are not. Whether or not the virus is active, and the way in which it travels directly affects the infection risk, muck like your risk of getting into an accident increases when driving a motorcycle vs an SUV. Aerosol science is the physics of how things travel through the air, even if they're just water droplets or gas vapors.
Masks. Assuming the quality is good, and you wear it properly, a mask greatly reduces the amount of virus that you may transmit to others, or others to you. There is nothing else more effective to control spread at the source.
Distance. The US recommends 6' distance, but note that this is merely a simple, practical distance. When you dig into the science, many recommend 12' or even 20'+ because many other air qualities factor in, such as elaborated in the below paragraphs. Meanwhile, at the start of the pandemic, and likely thru today, some countries recommend only 1 meter (just over 3') or 1.5m. Therefore, 6' is just what the US settled upon.
Air changes. The primary goal in an indoor space is to improve the air circulation frequently. This is often measured as air changes per hour, or ACH. A typical room in a home is only 0.5, or 1/2 the volume of air is changed out per hour. Flipping that fraction means it takes 2 hours to change out the air once. A typical healthy rate is an ACH of 6. Remember that a high ACH does not mean fresh air, just that air is moved in/out. For example, the ACH in an airplane is 20+. Most do not think airplanes have 'good' air because a lot of it is recycled, feeling 'stale,' but airplanes use high grade filters so when the air is recycled, it's been 'cleaned.' Do keep doors closed to a private office or meeting room when you're alone in there, but 'air it out' for the next person between uses by keeping the doors open.
Fresh air. Fresh air ventilation from the outside is ideal. So do keep open any exterior windows and doors, even if it's cold outside. Even better is cross ventilation so open that door on the opposite side of the room. Similarly, increase/open up the fresh air intake for the HVAC system, if possible.
CO2. Humans breathe out carbon dioxide, CO2. If someone is sick, they breathe out their CO2 along with germ-carrying droplets. Measuring the CO2 level in the air will tell you how much people are breathing out in your room...and how much air is being changed out. If air builds up, then CO2 builds up. If that air is infected, then health risk is increased. A low CO2 level is <600 parts per million, or ppm; 600-800 ppm is still acceptable. A CO2 monitor/sensor measures the CO2 levels so you can respond accordingly by opening more doors or windows, turning on that fan, filter or humidifier, or even leaving the room. Measuring CO2 is therefore a way to see if a space has poor ventilation. A CO2 monitor can ease your anxiety that the air quality is indeed less risky, despite however you may emotionally feel at the moment.
Humidity. "Humid" air means there's high water content, or high "relative humidity" (RH). It feels humid when the RH is between 40-60%, but then this is also the range that reduces the distances that COVID-19 can travel, and therefore reduces infection risk. Be careful to not keep a room too humid for too long (60%+) or you can cause mold to accumulate. Winter air tends to be drier, so adding a humidifier will reduce infection risk. Few humidifiers however can fill a sizable room such as a classroom, so I recommend placing it near a teacher, and point it away from the teacher and others. Perhaps place it in front and to the left of you, and direct it to the right for a cross 'breeze.'
Wash hands. It is more readily feasible to wash your hands than to sanitize every conceivable surface around you. Yes viruses do reside on surfaces, but they have not infected anyone. A virus will not jump off a surface to infect you. You do not even need to wipe down groceries, for example.
Plastic desk dividers and face guards. A viral plume is like cigarette smoke - it hovers up and around anything that's partial height or width. Would a plastic divider initially reduce someone from blowing cigarette smoke into your face? Yes, ditto a viral plume. Does cigarette smoke pretty readily meander up and around? Yes. In fact, if there's a constant flow of virus onto a plastic divider, there can be an increase of virus on the other side. Imagine how air flows around an 18-wheeler and causes a suction of greater air flow at the back of the trailer. More viral plume will in fact gather on the other side of that plastic divider.
The air quality outdoors is infinitely better, but it is NOT 100% safe. Risk increases the closer you are to someone and the longer you socialize with them. Risk increases even further if you socialize with multiple people. Fifteen minutes is the rule of thumb, but like physical distancing of 6', it's a practical, simple amount of time to remember. There's no magical threshold of safety so that at 14 min. it's ultra safe, or suddenly dangerous at 16 min.
There's no single magic bullet with any of the safety recommendations. Everyone must use a combination of the above recommendations at all times with the primary goal of reducing risk, not eliminating risk. You can do a lot yourself to greatly reduce the risk of infection, and often very affordably.
Some of the above are not explicitly cited by the CDC or WHO. Due to government delays and other reasons, the CDC/WHO and other health organizations have not officially adopted all of these facts. There are also academic debates about aerosol vs small droplets vs large droplets and whether "airborne" is the proper syntax. For the rest of us outside of the science community, we only care that the virus travels through the air to infect others, and that there is water in the air that affects the virus' ability to travel through it.