After several gruesome incidents in which fans were struck by balls and shattered bats at games last season, Major League Baseball on Wednesday issued a recommendation for all 30 clubs to erect protective netting in front of the most exposed field-level seats from one dugout to the other.

Some clubs like the Boston Red Sox, who had two patrons hospitalized after being struck at Fenway Park, immediately promised to comply with the voluntary directive. Most, if not all, teams, are expected to join in before opening day.

Other clubs, like the New York Mets, the Pittsburgh Pirates and the Minnesota Twins, already have netting down the first- and third-base lines. The Mets have had their netting up since Citi Field opened in 2009.

MLB officials, sobered by the summer’s bloody incidents, have been studying the matter for several months and hired a consulting firm to work with teams and help them install the netting. The hope is to keep the netting as unobtrusive as possible while providing protection.

“There are options that are more translucent,” said Dan Halem, MLB’s chief legal officer regarding the material for the netting. “The goal is to enhance safety while continuing to provide that up-close experience to the game and the players that fans enjoy at baseball games.”

Some seating could remain vulnerable to high-speed projectiles. Halem said teams could elect to extend their netting farther down the lines than MLB’s recommendation, which calls for the netting to extend from the existing screen behind home plate to the closest edge of the dugout. In Japan, some stadiums have netting that reaches all the way to the foul poles. Whistles blow when balls are headed for the seats. After each foul ball signs urging fans to pay attention are illuminated on the scoreboard. Some stadiums even have signs in the far reaches of the upper decks where balls could not possibly land. And some stadiums have a row or two of seats in front of the netting and provide fans with helmets under the mutual understanding of the risk involved.

In the United States such precautions are more rare, and fans are generally more vulnerable. In June, a woman near the third-base dugout at Fenway Park was struck by the broken bat of the Oakland Athletics’ Brett Lawrie. She bled profusely, was carried out on a stretcher and spent a week in a hospital with what was described as life-threatening injuries. A month later another woman in the same seating area was struck in the forehead with a foul ball and required 40 stitches.

The Red Sox said they planned to consult with season ticket holders in the affected areas before constructing the new netting.

“The club is in the process of evaluating different design options to identify the best solution for Fenway Park,” a Red Sox statement said.

Part of the recommendation by MLB calls for notification at the time of purchase about whether the seats are behind the netting and for a campaign to heighten awareness of the potential dangers if fans choose not to sit behind the netting.

One of the growing problems cited in recent years is that many fans often look down at their smartphones rather than pay close attention to the action.

A group of ticket holders seeking enhanced protection filed a class-action lawsuit against MLB in July in U.S. District Court in Northern California. The claim cited a number of factors that made today’s baseball games more dangerous, including bats that splinter more easily, and video boards and other distractions, like enhanced Wi-Fi connectivity.

The suit, led by an Athletics season-ticket holder, cited a 2014 Bloomberg News survey that said about 1,750 people were injured at MLB games each year.

Joe Torre, who is in charge of baseball operations for the league is looking at ways to enhance player safety, and said the same went for the fans.

“We don’t want to carry guys off the field,” he said. “We certainly don’t want fans in the stands to not stay healthy.”

Baseball would not be the first sport to add netting to enhance fan safety. In 2002, 13-year-old Brittanie Cecil died as a result of the injuries she suffered when she was struck in the head by a hockey puck at a game between the Columbus Blue Jackets and the Calgary Flames. The following year the NHL added netting behind the goals in all its arenas.