Nightingal, and Robertson before her, argued for better designs in hospitals to overcome these issues. We are over 150 years on from this arguement which has already been proven.

Using a digital sensor isn't required. The spread of various Corona viruses and others increase during colder weather and are more likely to spread in enclosed environments with limited air flow.

Cafe door shut, no air exchange in place, it's winter and half the clientele are reaching for hankies. Your probably catching a cold.