Collectors and dealers of fragile, phenomenally expensive art have never wanted for reasons to stay awake at night. A piece could plunge from the wall. Somebody could stumble into it, or step on it, or add a new color to it with a splash of red wine.

But those responsible for safeguarding art will soon have a new category of anxiety- the possibility that airline employees could open carefully crated works of art to search them the way checked baggage is sometimes searched now, poking around Picassos instead of sweaters and socks.

The Transportation Security Administration [TSA] has mandated that beginning on August 1, 2010, all items shipped as cargo on commercial passenger airlines [estimates are that as much as 20% of art shipped around the world moves this way] will have to go through TSA airline security screening.

Since February 2009, airlines have been required to screen half of the passenger-air cargo. But shippers say that several categories of cargo - including fine art, pharmaceuticals, high-tech equipment and perishable food - have, to date, almost always been passed over when airlines have discretion of searching certain cargo unless an explosives-residue test or bomb-sniffing dog give reason to do so.

News of the requirement began to spread. Many large museums have enrolled in a federal program that allows them to create secure screening facilities within their own buildings. In these rooms institutions can inspect art, crate it and mark it with special seals, locks and tape that will mean that the chances of it being rescreened by airline personnel are miniscule. Many large art shipping companies have also become certified to screen and securely pack art themselves.

Art shipping experts say that the burden of the new regulations will fall more heavily on galleries and private dealers than on museums. Galleries often put together shows much more quickly and strike last minute deals for buying and selling art, and that can mean that a piece of art in New York must be in Zurich or Beijing the next day.

Douglas Brittin - air cargo manager for TSA - said the likelihood of airline personnel needing to open art crates or other complex cargo would probably remain low even after the August inception date considering on any given day over 13,000 tons of cargo is transported by passenger airlines. But the new rules could lead to delayed shipments.