Occasions For Tayammum And Can It Be Done In The Absence Of Dusty Surface
There are three occasions or situations mentioned in the Quran for dry ablution: Travelling, Sickness and absence of water. “But if you are ill, or are travelling, or have just satisfied a want of nature, or have cohabited with a woman, and can find no water-then take resort to pure dust, passing therewith lightly over your face and your hands. God does not want to impose any hardship on you, but wants to make you pure, and to bestow upon you the full measure of His blessings, so that you might have cause to be grateful.” (5:6) So during travelling you can do tayammum. Travelling itself an excuse for Tayammum. it is not necessary to use rock or dust, anything pure can serve the purpose. Having said that, Muslims should not be shy for performing his or her religious duties in front of people, millions of Muslims do that. However for fear of persecution one can be advised to not to perform his or her religious rites in public.