  Aerosolized droplets play a central role in the transmission of various
infectious diseases, including Legionnaire's disease, gastroenteritis-causing
norovirus, and most recently COVID-19. Respiratory droplets are known to be the
most prominent source of transmission for COVID-19, however, alternative routes
may exist given the discovery of small numbers of viable viruses in urine and
stool samples. Flushing biomatter can lead to the aerosolization of
microorganisms, thus, there is a likelihood that bioaerosols generated in
public restrooms may pose a concern for the transmission of COVID-19,
especially since these areas are relatively confined, experience heavy foot
traffic, and may suffer from inadequate ventilation. To quantify the extent of
aerosolization, we measure the size and number of droplets generated by
flushing toilets and urinals in a public restroom. The results indicate that
the particular designs tested in the study generate a large number of droplets
in the size range 0.3$\mu m$ to 3$\mu m$, which can reach heights of at least
1.52m. Covering the toilet reduced aerosol levels but did not eliminate them
completely, suggesting that aerosolized droplets escaped through small gaps
between the cover and the seat. In addition to consistent increases in aerosol
levels immediately after flushing, there was a notable rise in ambient aerosol
levels due to the accumulation of droplets from multiple flushes conducted
during the tests. This highlights the need for incorporating adequate
ventilation in the design and operation of public spaces, which can help
prevent aerosol accumulation in high occupancy areas and mitigate the risk of
airborne disease transmission.
