The Consumer Product Safety Commission mandated safety standards for folding play yards on Wednesday but scrapped a proposal that was meant to address the hazards that led to the death of a 3-month-old girl a year ago.

The standards, unanimously approved by the four-member commission, build upon voluntary ones put in place by the industry. Most important, they require that these popular portable cribs be tested to ensure that they meet stringent safety criteria. Since 1985, 20 recalls involving play yards have taken place — as have numerous deaths.

While regulators say the new standards address the most serious hazards, consumer groups complained that the industry succeeded in removing a provision that dealt with play yards that come with bassinets and other accessories.

The 3-month-old girl, whose name has not been disclosed, was napping in a bassinet that snapped onto her play yard when the bassinet detached and tilted, pushing her face into the mesh side wall of the play yard. She suffocated. The play yard was not assembled properly and the stricken provision was meant to deal with that issue.

“It’s disheartening that we couldn’t get this taken care of,” said Nancy Cowles, executive director of Kids in Danger.

Still, the new rules are significant, regulators and consumer advocates agree.

When they take effect in December, they will provide baseline safety criteria that all play yards — also known as pack-and-plays — must meet before they reach stores. Those standards will have the force of law, which empowers regulators to take swift action against violators.

Danny Keysar’s parents say these rules are a huge leap in safety.

In 1998, when Danny was nearly 17 months old, he died at his day-care provider’s house in Chicago after the side rails of his folding Playskool Travel-Lite collapsed into a V-shape and clamped around his neck. The play yard had been recalled, but his caregiver didn’t know it.

About 1.5 million portable cribs with this side rail defect have been recalled. At least 19 deaths have been tied to them. Though the deaths tapered off as the industry adopted improved standards, some of these play yards are unaccounted for, according to Kids in Danger, which Danny’s parents founded.

Against that backdrop, Congress approved a bill in 2008 that beefed up the Consumer Product Safety Commission’s powers and named a portion of it after Danny. That portion orders the agency to examine two voluntary standards for nursery products every six months and make them mandatory — strengthening them if needed. The play-yard standards came as part of that directive, and regulators had been working with the industry for months to get them done.

But the collegiality fell apart soon after the CPSC learned of the 3-month-old’s death.

To mitigate the hazard of incorrect assembly, the CPSC added language that would make it tougher to successfully put together a play yard that’s missing parts — as was the case with the play yard of the girl who died last year. One proposal would have had manufacturers stitch together all the parts so that none could be left out.

In May, the industry’s trade group asked that this provision take effect later than originally intended, and the CPSC agreed. But this month, half an hour before the commission held a briefing on the standards, it received a letter from the group accusing the CPSC of violating the law by not soliciting public comment on that provision.

The move infuriated Chairman Inez Tenenbaum, who immediately called the group. She said she was told that one of the group’s members, a company called Arm’s Reach, objected to the provision. At the public briefing, Tenenbaum lashed out at the Juvenile Products Manufacturers Association.

“That is most disappointing for people to act this way to us, [like] we have done something wrong when they were at the table the entire time,” Tenenbaum said in a raised voice.

The commission now plans to deal with this issue separately, and the trade group said it is pleased with that outcome. Consumer advocates say that’s the way safety reform goes.

“We have to keep pushing all the time,” said Linda Ginzel, Danny Keysar’s mom. “It’s never put a red ribbon on this and it’s done. It’s never done.”