One tool for reducing #COVIDRisk is to carry around a small portable #C02Monitor to see how safe an indoor environment is: the lower the C02, the better ventilated the space is. If the C02 gets above 600ppm to 700ppm, the COVID risk is elevated, so leave and go elsewhere. This is a small portable C02 monitor I've seen recommended by experts:
https://www.co2radical.com.au/product-page/aranet4-sensor