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Status Report, Vol. 45, No. 9 | September 8, 2010 Subscribe

More boosters earn top ratings for belt fit, but most still don't

Boosters are better than they used to be at fitting lap and shoulder belts on 4 to 8 year-olds to restrain them in crashes. So parents don't have to search as hard for a good fit for their child and their vehicle. Most belt-positioning boosters, though, don't offer consistently good fit in all vehicles. This is the bottom line in the Institute's third round of booster evaluations.

Researchers assessed the safety belt fit of 72 boosters, assigning the best ones the top ratings of BEST BET or GOOD BET because they correctly position belts on average booster-age kids in most vehicles. The worst performers are ones the Institute doesn't recommend because they do a poor job of fitting belts. Good boosters route the lap belt across a child's upper thighs and position the shoulder belt at midshoulder. The Institute doesn't conduct crash tests to evaluate boosters. The focus is on belt fit, not crash performance.

"For the first time top-rated boosters outnumber ones the Institute doesn't recommend," says Anne McCartt, Institute senior vice president for research. "Now more than ever manufacturers are paying attention to belt fit, and it's showing up in our ratings."

Twenty-one boosters are BEST BET models, and 7 earn GOOD BET. Another 8 aren't recommended at all. This represents a market shift. Last year only 9 seats out of 60 the Institute evaluated earned BEST BET.

Even though poor performers make up a smaller percentage of boosters evaluated this year, 36 fall in the middle because they don't consistently fit belts well on most kids in most cars, minivans, and SUVs. Most of these are backless boosters with good lap belt scores but not good shoulder belt scores.

"Unlike the top performers, consumers can't assume boosters in the in-between group will work in every family vehicle. Some may be fine, but parents still need to try them out to see if the lap and shoulder belts fit their kids correctly," McCartt says. Obvious red flags are lap belts that ride up on the tummy and shoulder belts that either fall off the shoulder or rub against a child's neck. McCartt advises parents to keep looking until they find a booster that fits.

Why fit matters

No federal standard dictates how a booster should position belts. The government's dynamic tests of crash performance don't measure what boosters are meant to do, and the National Highway Traffic Safety Administration only ranks boosters by how easy they are to use (see "Booster seats are the subject of a new federal law," Feb. 8, 2003, and "Child restraint ratings based on ease of use will continue, but NHTSA won't rate crash performance," Sept. 28, 2005). Manufacturers crash test boosters, but these simulations don't tell parents how boosters will fit kids in their cars. Every state and the District of Columbia has a child restraint law, but they differ when it comes to booster-age kids. In 27 states and D.C., the laws cover kids until age 8, with exceptions for size.

The Institute in 2008 began evaluating boosters to help make selecting appropriate ones less of a guessing game (see Status Report special issue: booster seats, Oct. 1, 2008, and "Which booster is best for me?" Dec. 22, 2009). Since then some manufacturers have adopted the Institute's test protocol and booster seat fixture to help evaluate belt fit on the new boosters they're designing. Britax Child Safety Inc. is one. The North Carolina-based company has one BEST BET (Britax Frontier 85) and one GOOD BET (Britax Parkway SG) this year.

The "protocols have been invaluable in confirming that our booster seats are designed to maximize belt placement and fit," Britax says.

Belts do the main job of keeping kids in boosters safe in crashes, but belts along with vehicle seats are designed for grown-ups, not children, so it's important for boosters to lift kids into position for lap/shoulder belts to provide proper restraint. Children 4-8 who ride in boosters are 45 percent less likely to sustain injuries in crashes than children restrained by belts alone.

Good belt fit

GOOD BELT FIT: The lap belt should fit flat across a child's upper thighs, not soft abdomen. Good boosters have belt-routing features that hold lap belts down and forward. The shoulder belt should cross snugly over the middle of the shoulder, in position for effective protection in a crash.

Poor belt fit

POOR BELT FIT: The lap belt is too high on the abdomen, and the shoulder belt is too close to the neck or off the shoulder.


How boosters are evaluated

Institute engineers assess boosters using a crash test dummy representing an average-size 6 year-old. They measure how 3- point lap and shoulder belts fit the dummy in each of the boosters under 4 conditions spanning the range of belt configurations in a wide variety of vehicle types. A booster's overall rating is based on the range of scores for each measurement.

Boosters come in 2 main styles, highback and backless. Some highbacks are dual-use. Removing the back converts them to backless. These boosters get 2 ratings, one for each mode, because belt fit can differ by mode.

Highbacks have built-in guides to route shoulder and lap belts and can offer some support for the head. Backless models have lap belt guides, although parents might need to use a plastic clip to properly position the shoulder belts in many vehicles. Not all manufacturers provide clips. Even when they do, many of the clips don't ensure a good fit. Twelve of the highbacks are combination seats that can be used as front-facing restraints for toddlers and then as boosters as children grow. In booster mode, parents remove the built-in harness and use vehicle lap/shoulder belts to restrain kids.

Four highbacks are 3-in-1s. These are similar to combinations but also can be used as rear-facing restraints for infants. Forty-nine boosters are carryovers from the Institute's 2009 ratings because they still are in production. These include 7 BEST BET models, 5 GOOD BET boosters, and 6 that aren't recommended.

Wider variety of seats to choose among

New this year to the BEST BET ranks are seats by Chicco, Cybex, Graco, Harmony, and The First Years. These manufacturers join Britax, Clek, Combi, Dorel, Evenflo, and Recaro, which had BEST BET boosters in Institute evaluations last year and have models in the latest round.

"Parents looking for top-rated seats now have more choices that include several affordable picks," McCartt says. "Consumers don't have to spend much money on a booster to get good all-around belt fit. In fact, shoppers can find several BEST BET boosters for $50 or less through online retailers."

The Institute's recommended boosters include a mix of highback and backless versions. Backless generally provides better lap belt fit, and older kids seem to favor this mode. Highbacks generally do a better job of positioning shoulder belts correctly in all vehicle setups. Either seat is fine as long as the belt fits right.

Harmony improves

It's clear that some manufacturers are taking the ratings to heart. Harmony Juvenile Products has 5 BEST BET boosters, more than any other manufacturer. One of them, the Harmony Secure Comfort Deluxe backless, wasn't recommended last year. The company modified it to eliminate the earlier problem with lap belt fit. Plus, the young Montreal-based company designed new seats to provide good all-around belt fit. Harmony's Dreamtime is the only dual-use booster the Institute has evaluated to earn BEST BET in both modes, highback and backless.

Harmony Dreamtime

Harmony's Dreamtime is the only dual-use booster that earns the Institute's BEST BET designation in both the highback and backless modes. Harmony has 5 BEST BET models, more than any other manufacturer. The company says it factors the rating protocol into its design process.

Michael Noah, senior vice president of Harmony, says his company factored the Institute's protocol into its designs. Having clear U.S. belt fit standards for boosters would benefit everyone, he says, since "good belt fit is the starting point for overall car seat safety." Noah thinks standards should go beyond the required dynamic forward impact tests to include side and rear impacts, plus belt-routing.

Another Harmony seat, the Baby Armor, is a BEST BET when used as a highback but isn't recommended as a backless booster. In highback mode, the lap belt is where it should be — flat on the thighs. The backless problem is that once the thickly padded back is removed, the dummy sits farther back in the booster so the lap belt ends up too far forward on the legs.

Dorel Juvenile Group has 5 seats that rate either BEST BET or GOOD BET, including the new Safety 1st Boost Air Protect. The firm sells seats under the names Cosco, Dorel, Eddie Bauer, Maxi-Cosi, Safeguard, and Safety 1st. Dorel also makes 4 boosters the Institute doesn't recommend, down from 7 in the prior round of evaluations. All 4 are combination or 3-in-1 models. They don't work well as boosters because they don't do a good job of fitting the lap or shoulder belt.

What should parents do if a booster they already have isn't one the Institute recommends using? McCartt advises parents in this situation to take note of how the safety belts in their vehicle fit their child next time they're in the car.

"If the booster isn't doing a good job — if the lap belt is up on your son or daughter's tummy or if the shoulder belt is falling off your child's shoulder — then find a replacement booster seat as soon as practical, but you'll probably want to keep using the old one until then," McCartt says.

Almost all boosters improve belt fit compared with a vehicle's belts alone. Children tend to slouch and fidget, especially on long trips, so belts get out of position. Boosters help make belts more comfortable for kids and keep them upright and in position for the best protection.

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