A method for real-time virus infection risk monitoring is provided. A CO2 sensor, a particulate matter sensor, a temperature sensor, and a humidity sensor are utilized to respectively detect an ambient CO2 concentration, an ambient particulate matter concentration, an ambient temperature, and an ambient humidity in a first environment. A first difference between an ambient CO2 concentration and a reference CO2 concentration and a second difference between an ambient particulate matter concentration and a reference particulate matter concentration are computed by a processor. The first environment is determined to have a high infection risk of a specific virus by the processor in response to a condition being met.