Milan, Jan. 3 (Reuters): Custodians of Michelangelo?s David are thinking of blasting air at dusty, sweaty tourists to stop them sullying the Renaissance sex symbol.

Months after a painstaking and costly clean-up of the 500-year-old nude statue, experts at Florence?s Galleria dell?Accademia found dust and humidity brought in by streams of tourists had begun to tarnish their top crowd-puller again.

?The tourists carry in heaps of dust from outside. Dust may sound innocent, but the city grime contains lots of chemicals. They also bring in humidity when it?s raining,? museum director Franca Falletti said.

Falletti said one possible solution was to have air blowing out from behind the five-metre marble statue, reversing an existing draught in the museum that lets dust settle on the famous boy with the slingshot.

Other options include another wash for David ? controversial because of potential damage to his delicate features ? or asking tourists to rigorously brush off before entering the museum. ?We will monitor the situation over the next two years, and are looking at all the options to find a good system of defence for David,? Falletti said.