Officials said they had repaired the fencing that was damaged after the pile-up which sent debris flying into the crowd and injuring fans on the final lap of Saturday's second-tier Nationwide race.
Halifax Health spokesman Byron Cogdell said that seven people were treated for injuries at their facility but two who had initially been listed as critical were now in a stable condition.
Another injured spectator was being treated at Florida Hospital Memorial Medical Center in Daytona Beach, but their condition was not available.
Fourteen other fans had been treated on site at the track before being released, said Daytona International Speedway president Joei Chitwood.
Chitwood said any fans in the affected area who were concerned about the safety of their seat position would be relocated.
"If fans are unhappy with...their seating location or if they have any incidents, we would relocate them. We will treat that area like we do every other of the grandstand.
"If a fan is not comfortable where they are sitting, we make every accommodation we can," he said.
NASCAR and the speedway could face millions of dollars' worth of claims from the injured, litigation that would likely center on the sturdiness of the safety fence that was supposed to keep fans from danger, according to several plaintiffs' lawyers.
"Maybe the fence should have been higher; maybe there should have been more spacing between the track and spectators," said Adam Levitt, a lawyer with Grant & Eisenhofer.
However, lawyers also said the auto-racing business would likely point to the disclaimers that it typically displays on tickets, which are designed to exempt NASCAR from any potential injury liability. They expected NASCAR would argue that fans knew what they were getting into when signing up for the race.
Both the speedway and NASCAR have said they will closely review the incident in search of any ways they could improve safety.
Chitwood said new, 22-feet-high (6.7 metres) fencing had been put in place three years ago following a review of a crash involving Colin Edwards at Talladega in 2009.
"If you look at our 55 years in the business, we have a pretty good safety track record. I think we are prepared today," said Chitwood.
However, three-times Indianapolis 500 winner Johnny Rutherford said a change might be needed.
"Maybe a double fence, one behind the other with some space in between to stop something like this," he told reporters.
"But there are a lot of things and NASCAR and Indy Car racing are looking at everything they can to make it safer.
"What happened yesterday was a terrible thing because we expect (danger) that is part of it, we have to roll the dice and move on but you don't want to involve the fans," he said.
NASCAR's senior vice-president of racing operations Steve O'Donnell said he would tell any nervous fans that organisers were confident of their safety.
"I would tell them that the fans are our first priority. Obviously we want everyone to be safe at an event," he told reporters.
"We've talked to the speedway. We are confident in what's in place at today's event. Certainly still thinking about those affected but we are confident to move forward for this race," he added.
Fans streamed into the 167,000-capacity venue on Sunday and there was little indication of concern over safety.
"I feel safe. I think anywhere you go you run the risk of being injured but NASCAR does everything they can to protect the fans. They treat the fans like royalty here, it is amazing," said Vinny Nigro of New York City.
Another fan, Brad Stefka from Springfield, Missouri, said that while not particularly worried he would avoid the seating closest to the track.
"I just won't get down low. I would imagine that everyone who comes knows there is some element of danger if the cars are going that fast, if there is going to be a serious impact," he said.