Screenshot: BASF (YouTube)

In the late 1990s and early 2000s, Volvo offered on its cars a radiator coated with a catalyst called “PremAir,” which promised to reduce smog as ambient air passed through the cooling module. Here’s how this fascinating technology worked.

As your car drives down the road, oncoming air flows through its grille, across the radiator’s fins and tubes to cool the coolant within, and then bounces around your engine bay before getting exhausted into the environment.

As I learned from an old-timer car journalist at a recent press event, it turns out that, in the 1990s, Volvo worked with New Jersey-based catalyst company Engelhard to use the radiator as a sort of “filter” for smog-producing, ground-level ozone that passed through it in a system called PremAir. Volvo first installed the technology on the 2000 Volvo S80 in late 1999; the company describes the “ozone eater” system in a 2002 press release, writing:

Ground-level ozone is formed through the combination of air pollutants and strong sunlight. It can cause respiratory problems in human beings and it also inhibits plant growth.

Volvo was the first carmaker in the world to tackle the problem of harmful ground-level ozone, with the introduction of PremAir®‚ in 1999. The car’s radiator is coated with a thin catalytic film that converts up to 75 percent of the ground-level ozone as it passes through the radiator, converting it into oxygen.

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According to an Automotive News Europe article from 1998, Volvo wasn’t the first company to look at the technology. It turns out, The Blue Oval had also taken a peek, with the news site writing:

Ford tested the smog-eating radiator concept in 1995 and was, for a time, enthusiastic about the prospects for PremAir. Engelhard said Ford found no technological or cost problems with the technology.

The problem was volume.

Ford said that not enough air passes through a radiator to make much of a difference in fighting air pollution.

‘It was just a decision based on how much good it does for the environment,’ said Ford spokeswoman Sara Tatchio.

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The story says that, according to Engelhard, the coating Ford rejected cleaned up not just ozone but also carbon monoxide (presumably turning it into carbon dioxide), and thus included precious metals like platinum that would have added between $500 and $1,000 to the cost of each vehicle. Volvo’s PremAir coating, the representative went on, only added about $50 per car because it focused solely on ozone reduction, and required just a cheaper “base-metal catalyst.”

In its own story about PremAir, the New York Times wrote in early 2000 about skeptics like transportation analyst with the Union of Concerned Scientists Roland Hwang, whom the newspaper said “results would vary widely depending on whether there was any ozone present to be broken down,” which is fairly obvious, but worth noting. He went on to criticize the tech further, saying:

‘’We see the Engelhard catalyst as a bit of a gimmick,’’ he said. ‘’It’s something the auto companies will use to try and gain some environmental points.’’

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Apparently Engelhard, now a part of German chemical company BASF, had talked up the technology quite a bit, and when PremAir didn’t quite work as well as promised, the stock market took note, with the newspaper writing:

Engelhard initially contended that widespread use of PremAir in Los Angeles would do more for the city’s air quality than the combined benefits of electric cars, reformulated gasoline and reduced driving, and its stock soared 66 percent over the next three months.

Engelhard later said testing had shown that the catalyst’s environmental benefits were ‘’less than originally projected’’ and the stock dropped.

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Still, as written in the New York Times, Volvo clearly found the tech to be effective, claiming that, on especially hot days, it could actually offset all the ozone generated by the car’s exhaust.

Image: BASF

The real benefit to car companies, and the one that the New York Times says got Ford to reconsider PremAir after rejecting it, has to do with emissions credits:

Another reason for renewed interest in PremAir is that installation of the technology can help carmakers meet strict clean air standards in California and other states, including New York and Massachusetts, that follow California’s lead.

Richard Varenchik, a spokesman for the California Air Resources Board, said a 1998 addition to the board’s rules granted low-emission-vehicle credits to auto manufacturers able to demonstrate that the PremAir system works effectively; those credits can be applied to a particular model to improve its overall treatment under C.A.R.B. guidelines.

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The issue, according to the story, was that California requires automakers to be able to monitor their emissions-control systems, which Volvo’s system didn’t allow.

‘’We haven’t seen it up and running on a car,’’ Mr. Varenchik said. ‘’C.A.R.B. doesn’t know how effective the system will be, or how much ozone it will destroy. The carmakers have to demonstrate to us that it works, and they have to guarantee it for seven years or 70,000 miles.’’

Still, Volvo ran with it. And it wasn’t only the S80 that got PremAir, with the article saying that California-only version of the Nissan Sentra also got it, as did the Volvo V70. In addition, Volvo also made it standard on the XC90 and XC70 SUVs, as well as the V50, S40, and S60.

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If you’re a member, you can read an SAE paper showing Volvo’s summer 1997 PremAir test results here. In the summary, the paper says that the system’s conversion of ozone-int-oxygen depended on the radiator’s (or AC condensor’s) surface area and, of course, the total volume of air flowing through it, though apparently conversion ranged between 47 percent and the 75 percent quoted in the Volvo press release above.

Apparently the coating—which AP wrote back in 1998 is supposed to last 100,000 miles on Volvos—is still available and is shown off on BASF’s website and YouTube channel, though I’m not sure which vehicles use it today. It’s even apparently EPA and CARB approved for “direct ozone reduction,” according to the company.

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Anyway, I figured I’d share that little bit of random Volvo (and apparently Nissan Sentra) history. Also, I really just have a thing for cooling systems.