They do make sleeves that attenuate the signals.

Link

And as another feature:

In 2006, a mobile security company, Flexilis, conducted an experiment in which the transponder of a partially opened e-passport triggered an explosive planted in a trashcan when a dummy carrying the chipped passport approached the bin. A video of the experiment was shown that year at a security conference.

Flexilis has suggested that the government adopt a dual cover shield and specifically designed RFID tag that would make the e-passport remotely unreadable until it is fully opened.

No changes have been made to the U.S. e-passport in response, according to the State Department.
- Some RFID critics wonder: Could government officials read the microchips in an enhanced driver's license or passport card by scanning people via satellite or through a cell phone tower network?

The short answer is no - because the chips in PASS cards and EDLs are "passive," or batteryless, meaning they rely on the energy of readers to power up. Passive tags are designed to beam information out 30 feet.

However, research is moving forward to make batteries tinier and more powerful, says Ari Juels, director of RSA Laboratories. A "semi-passive" tag that could transmit into the atmosphere when triggered by a reader "may be feasible at some point," he says.

Separately, a system called STAR, that adapts deep-space communications technologies to read passive tags from distances greater than 600 feet, was announced last year by a Los Angeles startup called Mojix, Inc. It uses "smart antennas" and "digital beam forming" to process signals in four dimensions - time, space, frequency and polarization. Mojix, founded by a former NASA scientist, promotes the technology for supply chain management and asset tracking.