LOS ANGELES (CBSLA.com) — Just like people, pets need to answer the call of nature when they travel.

With more passengers bringing their pets along, the U.S. Department of Transportation issued a rule requiring airports serving 10,000 passengers or more each year to provide animal-relief areas by Aug. 4.

They’re primarily intended for service animals, but traveling pets are welcome to use them.

Atlanta’s Hartsfield-Jackson Airport, the world’s busiest, has a 1,000-square-foot dog park outside its domestic terminal. The airport is building pet-relief facilities throughout its concourses and will have nine when the work is done.

About 160 American airports have pet-relief areas.

LAX,  John Wayne/Orange County and Ontario airports all provide small pet parks outside the terminals. This can be a problem if a pet or service animal needs to go after they’ve passed through security screening.

That’s not a problem at Palm Springs, San Diego or Fresno airports, where pet relief areas are accessible from inside the terminal.