Biological pollutants are contaminants produced by living things. As a result, they are often found in areas with excessive food or moisture.

Biological pollutants can include bacteria, viruses, pet dander/saliva, dust, mites, and pollen.

In buildings, these pollutants are commonly found near excessive moisture, like in humidifiers or an unvented bathroom, as excessive moisture can be a breeding ground for mold, mildew, and bacteria.

It is stated in the Regulation of the Minister of Manpower of the Republic of Indonesia Number 5 of 2018, that the Microbiological Parameters in the IAQ are the Total Bacterial Count and Total Fungus Number.