“These invisible particles go on to coat and spread onto surfaces like floors and counters; or objects like hand towels, bathmats or even toothbrushes.
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Toilets are scientifically proven to continue to produce contaminated toilet plumes over multiple successive flushes as indicated in the above video.
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Toilet aerosols are known to contain Norovirus, SARS Coronavirus, Salmonella and many other Diseases.” https://en.wikipedia.org/wiki/Toilet_plume

TLDR: always put the lid down before flushing.