Quantcast

U.S. Air Pollution Falling More Slowly Than EPA Data Suggests

Science
Los Angeles skyline. Prayitno Photography / CC BY 2.0

U.S. air pollution isn't declining as fast as the Environmental Protection Agency (EPA) has claimed, a study published Monday in Proceedings of the National Academy of Sciences revealed.

To track the levels of nitrogen oxides and carbon monoxide, two pollutants that contribute to smog formation, an international research team used satellite pollution measurements backed up by local air quality monitor readings.


They compared this to EPA data, which is based on readings from air monitors and pollution estimates from vehicles and industry, and came to a surprising conclusion.

While nitrogen oxide levels had fallen by a healthy 7 percent annually from 2005 to 2009, from 2011 to 2015 the decline stalled to a mere 1.7 percent per year. This meant a 76 percent slowdown in pollution decline and contrasted with EPA data, which put the slowdown from 2011 to 2015 at only 16 percent.

A graph showing the discrepancy between EPA and satellite nitrogen oxide measurements. Zhe Jiang, redrawn by Simmi Sinha, UCAR

"We were surprised by the discrepancy between the estimates of emissions and the actual measurements of pollutants in the atmosphere," lead author Zhe Jiang said in a National Center for Atmospheric Research (NCAR) and University Corporation for Atmospheric Research (UCAR) press release. "These results show that meeting future air quality standards for ozone pollution will be more challenging than previously thought."

The researchers, who were funded by NASA, the National Oceanic and Atmospheric Administration, the University of Colorado Boulder and the NCAR-sponsoring National Science Foundation, hypothesized that the difference between the satellite data and the EPA measurements of nitrogen oxide were due to three factors.

  1. The decrease in nitrogen oxide released by cars because of the widespread use of catalytic converters
  2. A relative increase in nitrogen oxide released by boilers and off-road vehicles
  3. A slower decrease in emissions from diesel trucks than expected due to the fact that effective catalytic converters for these vehicles are still being perfected.

The researchers found that carbon monoxide levels had also slowed their decline and hypothesized that this was due to the effectiveness of catalytic converters in cars.

NCAR scientist and study co-author Helen Worden told Bloomberg News that the slowdown in air pollution decline was influenced by the fact that, as the 1970 Clean Air Act succeeded in reducing pollution from cars and factories, pollution sources such as boilers and off-road vehicles that had fallen under the radar before were playing a bigger role.

"To some extent, this is a product of our own success," Worden said. "The relative contribution of those sources is now more important because cars and power plants have gotten better."

Unfortunately, the findings come at a time when the EPA is backtracking on its commitment to its former successes. Since December 2017, the EPA has passed four memos weakening controls on industrial air pollution. And in April, EPA head Scott Pruitt announced the agency would adapt less stringent car emissions standards through 2025.

Show Comments ()

EcoWatch Daily Newsletter

Kissing bug. Pavel Kirillov / Flickr / CC BY-SA 2.0

The Centers for Disease Control and Prevention (CDC) confirmed that the kissing bug, which can transmit a potentially deadly parasite, has spread to Delaware, ABC News reported Wednesday.

Read More Show Less
"Take the pledge today." Screenshot / StopFoodWasteDay.com

Did you know that more than a third of food is wasted or thrown away every year? And that only 25 percent of it would be enough to feed the 795 million undernourished people in the world? That's why today is Stop Food Waste Day, a chance to reflect on what you can do to waste less of the food you buy.

Stop Food Waste Day is an initiative of food service company Compass Group. It was launched first in the U.S, in 2017 and went global the year after, making today it's second worldwide celebration.

Read More Show Less
Sponsored
Pexels

By Franziska Spritzler, RD, CDE

Berries are among the healthiest foods you can eat.

Read More Show Less
Flames and smoke are seen billowing from the roof at Notre-Dame Cathedral on April 15 in Paris, France. Veronique de Viguerie / Getty Images

When Paris's Notre Dame caught fire on April 15, the flames threatened more than eight centuries of culture and history. The fire evoked shock, horror and grief worldwide. While the cathedral burned, French President Emmanuel Macron expressed determination to rebuild what the French regard as a sacred site.

Read More Show Less
An artist's impression of NASA's InSight lander on Mars. NASA / JPL-CALTECH

Scientists have likely detected a so-called marsquake — an earthquake on Mars — for the first time, The National Aeronautics and Space Administration (NASA) announced on Tuesday.

Read More Show Less
Sponsored
Hero Images / Getty Images

Across the political aisle, a majority of American parents support teaching climate change in schools even though most teachers currently do not.

Read More Show Less
Priit Siimon / flickr / cc

By Andrea Germanos

Lawyer and visionary thinker Polly Higgins, who campaigned for ecocide to be internationally recognized as a crime on par with genocide and war crimes, died Sunday at the age of 50.

She had been diagnosed with an aggressive cancer last month and given just weeks to live.

Read More Show Less
Pixabay

An E. coli outbreak linked to ground beef has spread to 10 states and infected at least 156 people, CNN reported Wednesday.

Read More Show Less