Simple viruses or colds can often lead to sinusitis because the cold causes the sinus cavity to obstruct, thus trapping bacteria in a closed space. Once in this closed space, bacteria multiply and lead to the pain and pus of sinusitis.
Keeping the sinuses healthy and bacteria overgrowth-free requires good ventilation of the sinuses.
A recent article in the American Journal of Respiratory and Critical Care Medicine cited a research project on humming. The scientists conducting this study found that humming leads to higher levels of exhaled nitric oxide, a gas produced in the sinuses.
It seems that humming exerts a positive pressure into the sinuses in a fluttering way that promotes their unblocking.
Another research group also studied humming and sinusitis and published their data in the European Respiratory Journal.
Both groups found that repeated humming sessions during days when people had colds markedly reduced the incidence of sinusitis.