Further increasing the formaldehyde concentration to 1 milligram per cubic meter led to a dramatic increase — up to 136.4 per cent — in cilia
beating frequency relative to the baseline value.
In contrast, when air mixed with 0.5 milligrams per cubic meter of formaldehyde was passed through the chamber, they observed a 7.4 per cent increase in cilia
beating frequency relative to the baseline value.
When fresh air was passed into the chamber, the researchers observed a 3 per cent drop in cilia
beating frequency relative to the baseline value.