#physics **Indoor air quality** For those being forced to go back to work. From the experience of my neighbours, you'll be back sick from covid a week later. I am impressed with a new generation of air quality monitors, at about $40 cdn. Quite the competition, so it will be going down.
I had the dubious honour of being in the first of the 'new wave' efficient office buildings in the 70's. Many people had to quit their jobs because they got so sick. For huge floor of 500 people, they recycled all the air through cheap filters, and had an opening of less than a sq ft for fresh intake. It was a soup of disease.