Nitrous oxide—better known as laughing gas — is used to make whipped cream, beer, and rocket propellant. It has been used by dentists since the 1800s – as well as by partiers who inhale “nitro” for giggles.  

But all humor aside, nitrous oxide is also an incredibly potent greenhouse gas. When released into the air, it is 273 times more powerful than carbon dioxide at warming the atmosphere. Nitrous oxide is also the most significant ozone-depleting pollutant that has not been banned.

On July 23, the Biden-Harris Administration announced new voluntary actions by industry to reduce emissions of climate-warming “super-pollutants,” including nitrous oxide. But the announcement included no regulations for nitrous oxide and no requirements for industry to control this super-pollutant.  

This isn’t the first time that EPA has passed on the opportunity to curb nitrous oxide emissions, which grew by 40 percent globally between 1980 and 2020.

The Environmental Integrity Project and Sierra Club in 2009 sued EPA, in part for failing to review and update technology-based limits for nitrous oxide, as required by the Clean Air Act. In response, the agency declined to regulate nitrous oxide while promising to continue studying the issue.  

In the 10 years following EPA’s decision, between 2012 and 2022, nitric acid plants emitted the equivalent of 102 million metric tons of carbon dioxide that could have been avoided. That’s enough to cause at least $19.4 billion in climate-related damage, including from flooding, wildfires, and crop losses, according to EPA cost formulas.

Nitrous oxide is not only a serious problem, it’s also seriously misunderstood.

Earlier this year, Supreme Court Justice Neil Gorsuch confused nitrous oxide with nitrogen oxide in writing an important decision in Ohio, et al. v. EPA, which blocked EPA limits on Midwestern states polluting their downwind neighbors.  

While such a high-profile flub bolsters arguments that justices should not be left to decide matters of science, it can be easy to mix up types of nitrogen-related air pollution.  

So to clarify the issue:  

Nitrogen oxides (NOx) are a group of compounds that contribute to the formation of ground-level ozone and contribute to acid rain. It includes nitrogen dioxide (NO2), a lung irritant that can cause and exacerbate breathing problems and other negative health effects, and nitric oxide (NO).  

By contrast, nitrous oxide (N2O) is a colorless non-flammable gas that has a slightly sweet scent and is a potent greenhouse gas that also damages the ozone layer.

The overwhelming majority—about two thirds-- of global nitrous oxide emissions from human activity come from agricultural practices. When nitrogen fertilizer is applied to soil under the right conditions, microbes that feed on that nitrogen release nitrous oxide into the air.  

Because farming is such a significant source of nitrous oxide, and because fertilizers are so widely used, reducing emissions from agricultural land is both a massive and worthwhile undertaking.

But a significant amount of global nitrous oxide emissions—14 percent—come from industrial sources, like coal-fired power plants and facilities that make key ingredients in nylon, chemical  fertilizers, and explosives. (These ingredients are nitric acid and adipic acid.)

According to the EPA’s Greenhouse Gas Reporting Program, industrial sources in 2022 reported emitting nitrous oxide in the amount equivalent to 17.5 million metric tons of carbon dioxide – as much as 4.5 coal-fired power plants running nonstop for a year. Nitric and adipic acid production accounted for 63 percent of that total—over 11 million metric tons.  

The technologies to nearly eliminate these emissions exist and are being used at many plants across the country and internationally. They have been around for decades. But about half the nitric acid plants in the U.S. still have not installed it.

During a conference in Washington D.C. in July about industrial nitrous oxide emissions, John Podesta, Biden’s senior advisor on international climate policy, underscored how achievable it would be to slash nitrous oxide emissions from nitric and adipic acid plants.  

“Reducing these emissions is cost-effective -- indeed it’s one of the most cost-effective ways of reducing emissions,” Podesta said. “The EPA finds that about 80 percent of industrial N2O abatement is available for under $20 per ton.”

“It’s not often that we find ourselves with an affordable and relatively straightforward way to eliminate emissions equivalent to tens of millions of cars on the road. Cutting industrial nitrous oxide emissions is that opportunity.” Podesta said.

Currently, efforts to mitigate nitrous oxide emissions are voluntary or limited to facilities that must reduce nitrogen dioxide emissions because they are in areas that are failing air quality standards for ozone or nitrogen oxides.

In the U.S., nine voluntary industrial nitrous oxide pollution control projects have registered with the Climate Action Reserve, a nonprofit that facilitates carbon trading. However, voluntary and market-based efforts have moved slowly and don’t provide an enforceable limit on future emissions. They are also ineffective under certain economic conditions, for example, if it no longer becomes economically favorable to maintain or replace aging pollution control technology.

The table below identifies the individual nitric acid production units in the U.S. and shows that about half of them—25 of 52—and many of the top emitters don’t have any nitrous oxide controls installed.  

The Biden Administration’s announcement on July 23 about voluntary greenhouse gas “super polluter” reductions by industry included some good news.

A Florida-based company called Ascend Performance Materials, which makes adipic acid and nitric acid and accounted for the lion's share of U.S. industrial nitrous oxide emissions until 2020, had installed technology to nearly eliminate nitrous oxide emissions.  

This improvement, however, came after the company announced it would make these reductions four years ago – but then failed to do so.

Two other sites have also installed abatement technology that would reduce or further reduce emissions—Dyno Nobel in Missouri and Invista in Texas. According to the White House, starting next year, these actions should reduce U.S. industrial N2O emissions by 50 percent compared to 2020. Industrial sources reported emitting 22.5 million metric tons (as carbon dioxide equivalents) that year.

While near-term reductions and industry-led efforts are promising, the White House did not include any commitment to review or establish enforceable limits on nitrous oxide emissions from all nitric acid plants. Doing so would send a clear signal internationally that the U.S. is starting to get serious about controlling nitrous oxide.  

Lead photo: CF Industries' Donaldsonville complex in Louisiana, one of the largest point sources of nitrous oxide emissions in the U.S.

Note: For this report, we adjusted nitrous oxide emissions to reflect the latest science on their global-warming potential.