Cleaning up highway truck traffic can lead to better air quality for the most vulnerable. EPA

Trump EPA Doing Something to Actually REDUCE Pollution from Trucks

, senior vehicles analyst | January 6, 2020, 2:53 pm EDT
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Today, EPA Administrator Andrew Wheeler announced an advanced notice of proposed rulemaking (ANPRM) to set more stringent pollution standards on heavy-duty trucks. This follows up on the 2018 announcement of the administration’s “Cleaner Trucks Initiative” and represents the only step thus far the administration has made to actually, you know, do its job and reduce pollution.

What’s next

An ANPRM is just the first step in the process to set stronger pollution standards for trucks, but the evidence is abundantly clear that what we have on the books today is not good enough. The last round of pollution standards was set almost two decades ago, and while the fleet has gotten significantly cleaner as those newer, lower-polluting diesel trucks have phased in, the real-world pollution reductions have not met expectations.

The last round of standards was expected to cut smog-forming emissions from new trucks by 90 percent; however, recent data shows that even the best performing new trucks emit in the real world more than 3 times the levels of pollution required under the current certification tests. The current standards do not adequately capture real-world performance, and as a result, the nearly 20-year-old rules are not yielding the local reductions needed.

It’s also worth pointing out that this positive step is taking place while the administration’s proposal to allow greater sales of highly polluting glider trucks is still on the table, which would significantly undermine any reductions of the “Cleaner Trucks Initiative.”

What’s at stake

Heavy-duty truck pollution is a critical factor in local air quality. In California, diesel trucks represent about one-third of all nitrogen oxide (NOx) smog-forming pollution, and even as newer, cleaner trucks enter the fleet, diesel emissions will continue to be the largest contributor to NOx pollution for the foreseeable future.

Pollution from diesel trucks is concentrated in freight corridors around the country, putting historically disadvantaged communities at risk. (Source: EPA)

But it’s not just California that’s impacted by dirty trucks—freight corridors in the Southeast (e.g., down to Atlanta) and in the Midwest (e.g., through Chicago) are heavily impacted by diesel emissions, leading to increases in both soot and smog as a result of emissions of NOx and particulate matter from diesel trucks.

Communities most at risk from the impacts of such emissions are those that live along these freight corridors or near ports, which have tremendous volumes of truck traffic. While these communities likely have the most to gain from stronger regulations, history has shown that there is no guarantee the federal government is willing to go far enough to protect these communities, since they’ve historically borne the brunt of the health impacts from transportation pollution.

What to look for

Because of its pressing need to address the air quality issues of its inhabitants, California has already been moving forward with setting more stringent pollution requirements for heavy-duty trucks, holding workshops for stakeholder engagement, supporting research on the next generation of pollution controls, and moving forward with complementary policies that advance electric trucks. Other states have echoed the need to move forward with stronger emissions requirements for trucks in light of federal air quality requirements, and state actions to reduce emissions from new trucks will likely go into effect in advance of any federal action.

With states and now EPA moving forward to set stronger requirements for heavy-duty trucks, the key questions for any standards will be 1) will these rules be technologically forcing, as required under the Clean Air Act; 2) will the agencies ensure that reductions on certification tests are matched by real-world reductions; and 3) will these reductions be maximized to protect those communities most currently impacted by truck pollution?

Given the slow turnover in the truck fleet, the lengthy EPA rulemaking process, lead-time restrictions preventing federal implementation until 2026 at the earliest, and a movement already underway towards zero-emission freight, it is possible that the actions undertaken by this administration could be the last set of national pollution standards ever set for diesel-powered trucks—as such, it is critical that this process expedites a transition to a cleaner, more sustainable, and more just freight system as we transition away from fossil fuels.


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  • Engine and truck manufacturers -Industry — actually reached out initially to EPA (Obama Administration days) with a request to further reduce the NOx emissions standards through more stringent regulation, followed by petitions from CA and then a number of NE states. Notable forecasters like McKinsey et al show diesels still the dominate mode of power for commercial vehicles – tractor trailer size trucks- well beyond 2040.

    • There’s no doubt that diesel vehicles will be on the road for decades to come–they’ve got extremely slow fleet turnover and last for a long time. But if they still represent the dominant source of new heavy-duty vehicle sales in two decades’ time, you might as well be relying on a magic wand to solve climate change.

      • Solving climate change is a big challenge, and industries like trucking making incremental but significant gains over large populations are going to be a major contributor to progress until and whenever a transition to alternatives takes place, and we have all electricity from 100 percent renewables to charge them; a concept not stressed a whole lot because we have a long ways to go on that.

        Getting more newer generation diesels – especially the 2027 variety on the road isn’t a magic wand or a unicorn but it is something that will guarantee steady progress toward lower carbon emissions from freight especially if they are using a lot more low carbon renewable biofuels.

  • CCM591

    Not sure I fully understand the EPA graphic on “Projected annual average Secondary PM2.5 concentrations in 2025 Onroad heavy duty diesel.” Is this a projection of secondary PM2.5 from heavy-duty diesel NOx emissions without the NOX emission restrictions proposed in the ANPR?

    If so, there doesn’t appear to be much bang for the buck, so to speak. Reducing PM2.5 concentrations by ~0.1 µg/m3 isn’t really going to help that much since Los Angeles’ 2016-2018 Design Value for PM2.5 is 14.7 µg/m3 per EPA data, which is 2.7 µg/m3 over the PM2.5 NAAQS limit (12.0 µg/m3). There aren’t any other non-attainment areas in the U.S. that would come into attainment with just this action based on a quick review of the EPA data.

    The regulatory agencies need to focus on other sources and PM2.5 precursor emissions than just diesel NOx emissions if they really expect much of a dent in ambient PM2.5 levels.

    • Not sure what’s confusing. The highest bin (encompassing much of the Midwest) goes up to 0.5 ug/m3. This is just for secondary PM2.5 from NOx, excluding the primary diesel PM2.5 which is also not insignificant and should also see a lower target as part of this rule. Point of including the graph was a reminder that NOx isn’t just about smog and ozone, though that is the clear primary target of reductions.

      I linked to the original EPA paper in the blog if you want to dissect all the additional contributing factors or see more details. There is no silver bullet to air pollution–while on-road diesel is one of the largest contributors, non-road diesel is another major sector that will need to be addressed. And while light-duty vehicles continue to be a problem, they at least will continue to see improvements as a result of the Tier 3 regulations that went into effect in 2017. But sure, more must be done.

      You can look at the various state comments I linked to to see their challenges — this is just an obvious easy target for emissions reductions because of its magnitude. Unfortunately, for air quality across the country, it is not the only area that needs to be addressed, but it has thus far been the only problem for which the current administration is even willing to look for solutions.

      • CCM591

        Thank you for your response.

        I did not initially notice that you had linked the EPA source for your graphic. I will read the paper for more detail.

        I appreciate regulatory challenges for improving air quality. It is my opinion that the regualtory agencies need to look at other emissions that just NOx. The other sources of PM2.5 precursor emissions could be, for example, ammonia emissions from mobile sources. There are currently no regulations for those NH3 emissions from mobile sources that I’m aware. NH3 is an extremely prolific SIA precursor because it reacts with both nitrate and sulfate.