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Jul 24, 2023

GASOLINE Particulate Filters On US Cars & Trucks Are A Good Idea

A $200 filter could dramatically lower particulate emissions from gasoline

A $200 filter could dramatically lower particulate emissions from gasoline engines.

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When gasoline is burned inside an internal combustion engine, a lot of junk is created that is not especially friendly to our lungs. Most of it we can't see, and so we ignore it, but that doesn't mean it isn't harmful to our health. Among the nasty stuff that exits the tailpipes of our vehicles are particulates — tiny bits that are so small they can cross directly into our bloodstream in our lungs. From there, they get carried to all the organs in our body. They are stored in our liver, pancreas, and gonads. They also infiltrate our brain, where they can lead to cognitive difficulties, especially in younger humans.

Emisions Analytics is the leading independent global testing and data specialist for the scientific measurement of real world emissions and fuel efficiency for passenger and commercial vehicles and non-road mobile machinery in the world. In a report released this week, it says most cars in Europe and China are now sold with tailpipe particle filters, known as gasoline particulate filters or diesel particulate filters, but that is not the case in the US.

A gasoline vehicle with a filter emits around 0.9 x 1011 particles per mile (90 billion), but without a filter it is about 6.3 x 1011 (630 billion), according to testing conducted by Emissions Analytics. With about 300 million internal combustion engine (ICE) vehicles likely to be on the road in America on average over the next 10 years, each traveling an average of 10,000 miles per year, that puts the total number of ‘unnecessary’ particles emitted at 1.6 x 1024, or 1.6 septillion particles.

If you are math challenged, as I am, here's a handy way to envision how big a number a septillion is. If each of those particles were a dollar bill, the whole of the US could be carpeted over half a mile deep in money. Oh.

Image credit: Emissions Analytics

Some of those particles are as small as 10 nanometers. A nanometer is one billionth of a meter. Emissions Analytics says those ultrafine particles, when inhaled, can be drawn deep into the lungs and cross the blood-brain barrier, with potential effects on cognitive development. The direct link to negative health outcomes is not generally considered as proven yet, but Europe has nevertheless regulated due to the weight of evidence and as a precaution. European particle-number-based standards have led to the widespread adoption of GPFs, which are effective at trapping these small particles. This was quickly adopted by China and India.

On average a gasoline vehicle without a filter emits around 0.070 mg of particulates per mile. By contrast, a vehicle with a filter emits 0.027 mg per mile. Since vehicles with internal combustion engines are likely to be around for the next several decades, Emissions Analytics says we should do what we can to reduced the pollution they leave in their wake as much as possible.

So how much does one of those fancy, schmancy GPFs cost? Less than $200. Is your brain worth $200? How much is it worth for your children to have brains that function at the highest level? This isn't rocket science here, people. Are we really prepared to sacrifice our health and the health of our kids for the sake of $200? EA points out the cost of the filter is about equal to the cost of a set of floor mats from a BMW dealer for the X5 vehicle used in their comparison tests.

The company ran a number of test using virtually identical vehicles sold in both the US and the UK. The UK car were fitted with gas particulate filters; the UK cars were not. For more on the methodology used to conduct these tests, please see the press release link above. "Few things in emissions control are a no-brainer. Mostly, awkward trade-offs between cost, vehicle utility, and emissions reduction have to be resolved. In this case, the benefits appear high, costs relatively low, and risk minimal," Emissions Analytics says.

There is an additional benefit to particulate filters, EA says. First, the efficiency of GPFs tends to improve with the age of the filter, so the positive effect, if anything, grows. Second, those filters can capture particles in the atmosphere from other sources. We hear a lot of EV opponents nattering on these days about how electric vehicles are heavier than gas powered equivalent models and that means EV tires shed more particles. That is true, as far as it goes. EA says its tests show a 21% increase in tire particle mass emissions for every 500 kg extra vehicle mass — roughly equivalent to the mass of a large battery pack.

Of course, that tire particle argument conveniently ignores all the carbon emissions and particulates shooting out of the back of those cars or treats them as irrelevant. And, as EA notes, all cars are getting heavier as customers gravitate toward larger and larger vehicles. That being said, however, GPFs could have the added benefit of removing all small particles from the air. In other words, gas-powered vehicles could help clean up those tire particles left by EVs.

The US insists on dealing with vehicle emissions indirectly. The reason can be traced back to the OPEC oil embargoes of 50 years ago. Suddenly, fuel economy became the number one metric everyone cared about and so that's the metric the information on the Monroney stickers affixed to new cars was designed to inform shoppers about. Later, as the focus began to shift from fuel economy to exhaust emissions, the government decided to leverage its existing test protocols to measure emissions.

Here's how it works. A car that gets 20 mpg of gasoline emits more pollution than a car that gets 30 mpg. So if you want to lower emissions, simply raise the fuel economy requirement. Unfortunately, this 2-step process really doesn't measure actual emissions at all. It relies on formulas and assumptions that distort reality rather than revealing it.

Europe, China, and India do directly what we do indirectly, with a far better outcome for their citizens. The US could change the way it does things, but that leaves the whole process subject to political pressure and court challenges. "If it ain't broke, don't fix it," is the conventional thinking and any suggestion that the system really is broken is batted aside.

For the sake of $200, the US could significantly reduce pollution from ultra-fine gasoline particulates. Is that too high a price to pay?

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new."

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