How long can dangerous covid survive in the air?

Years ago, I thought I heard that covid can survive in the air for up to 16 hours (it may have been under laboratory conditions, I'm not sure). Recently, I found the following source, which suggests it can survive in the air for three days: https://www.verywellhealth.com/how-long-does-covid-live-on-surfaces-8546811 I have read that factors such as temperature, humidity, air flow, and CO2 can affect the survivability of covid, and I think it has been suggested how long covid) survives might not mean it can remain infectious for that long -- hence "dangerous covid" for my concern is not to get myself or anyone else infected. Do I need to avoid spaces where anyone else has been within three days and vice versa?