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EPA Phasing in Cleaner Diesel Engines; PA Has Few Limits on Existing Dirty Diesel Engine Emissions

For the first time in 20 years, the U.S. Environmental Protection Agency (EPA) is imposing new, more stringent standards on certain heavy-duty on-road diesel-powered vehicle emissions - specifically nitrogen oxides.

This rule is the first part of the EPA’s Clean Trucks Plan designed to reduce emissions from heavy-duty on-road vehicles beginning with model year 2027. The two other parts of the Clean Trucks Plan will be published later this year and will be aimed at reducing emissions of greenhouse gases from heavy-duty on-road vehicles and emissions of greenhouse gases, NOx, and particulate matter from medium- and light-duty vehicles.

Emissions from heavy-duty diesel engines are notoriously bad for human health and the environment. They increase concentrations of ozone, particulate matter, NOx, carbon monoxide, and air toxics in the ambient air - especially close to traffic corridors that tend to be located where people live and work.

These pollutants increase the risk of respiratory illness, cardiovascular problems, cancer, and even premature death in those who breathe them.

Although the new NOx emission standards for heavy-duty trucks focus on reducing levels of NOx and ozone in the ambient air, they will also - as a collateral benefit - reduce trucks’ emissions of particulate matter, carbon monoxide, and air toxics.

Besides reducing emissions, the rule for heavy-duty trucks that EPA published last December also will apply the new emission standards to a broader range of operating conditions (including idling). The rule will also at least double the number of miles that manufacturers must warrant engines will meet the new emission standards applicable to them.

EPA estimates that by 2045 (when the rule’s full impact will finally be felt – heavy-duty engines have long lifespans and dirty engines in service now may not be replaced for many years) the new standards for heavy-duty diesel trucks will prevent hundreds of premature deaths and thousands of illnesses annually.

EPA said that by 2045 the value of the health benefits from the rule will be between $10- $30 billion dollars annually and estimates that the cost of complying with the rule will be less than $5 billion dollars annually.

And *that* raises the question: Between now and 2045, what rules are in place to limit harmful emissions from heavy-duty diesel trucks? At least here in Pennsylvania, the answer unfortunately is “not many.”

Here’s what the Keystone State does regulate:

First, the Clean Air Act makes it illegal to tamper with or disable diesel (or any other) vehicles’ emission controls; there is a temptation for truck owners to do this because the controls reduce both the power and efficiency of trucks’ diesel engines.

Second, Pennsylvania restricts idling by larger diesel vehicles in many situations.

“There is, however, no third,” Baillie said. “Pennsylvania does not require diesel vehicles’ emissions or emission controls to be inspected.”

That means dirty, heavy-duty diesel engines are subject to less regulatory oversight than are less-polluting gasoline-powered cars, which must have their emission control systems inspected annually in many parts of the state.

Further, other than limitations on idling, there are no other restrictions on emissions from the operation of diesel trucks in Pennsylvania.

In contrast, a few other states – Maine, Rhode Island, and Utah – do impose an emission inspection requirement on heavy-duty diesel vehicles. Also, in a few states, high-opacity emissions from diesel vehicles operating on the highways can be against the law:

  • Colorado prohibits diesel vehicle emissions that “create an unreasonable nuisance or danger to the public health, safety, and welfare,” and have opacity of at least 20%. The prohibition does not apply to emissions during the start-up of a cold engine.

  • Georgia prohibits diesel emissions of more than 30% opacity. The prohibition does not apply “during periods of acceleration and deceleration not to exceed 10 continuous seconds or 1,000 feet.”

  • Maine has a prohibition against rolling coal that makes it illegal to operate a diesel vehicle with a gross vehicle weight rating under 18,000 pounds that emits smoke because of an alteration to the vehicle’s pollution control system.

  • Virginia prohibits diesel vehicle emissions of 20% opacity or more that last for longer than five seconds “after the engine has been brought up to operating temperature.” The prohibition only applies in a few counties and cities in northern Virginia.

Each of these states makes smoke reader training available to police officers and any other government employees who are empowered to enforce the prohibitions.

Annual emission inspections and prohibitions on extended, high-opacity emissions give truck drivers incentives to operate their vehicles properly and keep their engines well-maintained with pollution controls in good working order, which helps reduce the vehicles’ emissions.

“These are measures that every state - including Pennsylvania - can and should take to limit emissions from dirty diesel engines until the Clean Trucks Rule takes effect over the coming decades,” GASP Executive Director Patrick Campbell said.

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