What’s humidity control got to with fresh air?

Organisms’ survival rate varies based on Sterling Relative Humidity (RH).

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This chart was taken directly from the ASHRAE handbook suggesting that bacteria, viruses, mold, etc. survival varies across dryer and humid environments. The optimum is between 40-60%. Although this study is not from COVID but on coronaviruses, and with the assumption that all coronaviruses have similar traits. Combining parameters of a higher temperature of 105’F (40’C) degrees and relative humidity between 40-60% in a normal indoor conditions can deactivate a lot of viruses.

Malaysia's RH on average is 80% and temperature ranges from 27-33’C between day and night. These data can easily be obtained from https://weather-and-climate.com/. Indoor air-conditioning will reduce humidity, but adding a humidifier, or bringing in the untreated outdoor fresh air with high natural humidity will increase it. Besides stretching your air-conditioning system to work harder.