Covering when sneezing
Abu Hurairah (radi Allahu anhu) reported: Whenever the Messenger of Allah (sal Allahu alaihi wa sallam) sneezed, he would cover his mouth with his hand or a piece of cloth, suppressing the sound this way.
[Sunan Abu Dawud - classed as Hasan Sahih by Shaykh al-Albaani]
This Hadith stresses a very important point. In the presence of others, the one who sneezes is supposed to put his hand or handkerchief over his mouth so that the explosive sound may be suppressed.
The other benefit of this precaution is that it avoids causing an uneasy feeling to persons sitting beside him.
And Allah knows best!