Parameters used
| Parameter | Symbol | Description |
|---|---|---|
| Air change rate | ACH | The number of times air is replaced in a room per hour |
| Aerosol diameter size | d | The diameter of aerosol particles (μm) |
| Biological decay rate | λdecay | The rate at which the virus decays biologically (h−1) |
| Deposition fraction | fdep(D) | The fraction of particles deposited in the respiratory tract (−) |
| Dose–response relationship | ID63.2%; ID50% | The infectious dose required to infect 63.2% or 50% of the population (RNA copies) |
| Droplet volume | DV | The volume of each aerosol/droplet (mL) |
| Event reproduction number | R | The number of new disease cases divided by the number of infectors |
| Efficiency of face mask | η | The inward efficiency of the face mask (values between 0 and 1) |
| Exhalation rate | ER | The volume of air exhaled per hour (m3/h) or per second (L/s) |
| Fraction of infectious virus | finf | The fraction of airborne virus particles that remain infectious (−) |
| Gravitational settling | λdep | The rate at which particles settle due to gravity (h−1) |
| Host immunity of the exposed host | HIexp | The immunity level of the exposed individual (−) |
| Infection risk probability | P | The probability of infection (%) |
| Inhalation rate | IR | The volume of air inhaled per hour (m3/h) |
| Number of infectious individuals | I | The number of infectious individuals in the room |
| Number of susceptible individuals | Ns | The number of susceptible individuals in the room |
| Particle emission concentration | PEC | The number of particles emitted per cubic centimeter (#/cm3) |
| Particle emission flow | PEF | The flow of emitted particles per second (#/s) |
| Probability of infection (event-based) | Pevent | Probability of infection based on reproduction number and population size (−) |
| Quanta concentration in air | n(t) | Quanta concentration in the air over time (quanta/m3) |
| Quanta emission rate | S | The rate of quanta emission per hour (quanta/h) |
| Relative percentage difference | RPD | The relative percentage difference between two tools (%) |
| Relative reduction index | The relative reduction in infection risk (%) | |
| Removal mechanisms | λ1, λ2 | The rate of removal mechanisms before and after intervention (h−1) |
| Room volume | Vroom | The volume of the room (m3) |
| Total exposure time | t | The total time of exposure (hours) |
| Transmissibility factor | Tvoc | Transmissibility factor for the variant of concern (−) |
| Ventilation rate | λdep | The rate at which air is ventilated (h−1) |
| Viral concentration in air | N(t) | Viral concentration in the air over time (RNA/m3) |
| Viral load | VL | The concentration of viral RNA copies per milliliter (RNA/mL) |