A recent study conducted by the Massachusetts Institute of Technology (MIT) indicates that climate change may complicate efforts to reduce smog in several regions around the world, particularly in eastern North America and western Europe.
The study explains that rising temperatures caused by global warming will reduce the effectiveness of industrial emission reduction policies, making it increasingly difficult to control air pollution in the future.
Smog’s Growing Threat: How Climate Change Is Making the Air We Breathe More Dangerous.
Smog’s Impact on Health
Smog mainly involves ozone near the Earth’s surface — a harmful pollutant that poses serious risks to public health. It forms when sunlight reacts with pollutants such as nitrogen oxides (NOₓ) and volatile organic compounds (VOCs).
Although previous efforts to cut these emissions have improved air quality, the study warns that rising temperatures could increase natural emissions of nitrogen oxides from sources like soil. This would, in turn, reduce the effectiveness of human measures to curb these pollutants.
The researchers combined a climate model that simulates weather factors — including temperature and wind speed — with a chemical transport model that tracks how different substances move and interact in the atmosphere.
Protecting Air Quality
By generating a range of possible future outcomes, the researchers’ integrated approach better captures the natural variability of the climate, allowing for a more complete picture than many earlier studies.
Amy Lu Ryu, a graduate student in MIT’s Department of Earth, Atmospheric, and Planetary Sciences and the study’s lead author, explains:
“Future air quality plans should account for how climate change affects the chemical makeup of air pollution. We may need deeper cuts in nitrogen oxide emissions to meet the same air quality goals.”
The Challenge of Ozone Control
Ground-level ozone differs from the protective ozone layer in the stratosphere that shields the Earth from harmful ultraviolet radiation. Instead, it irritates the respiratory system and harms humans, animals, and plants alike.
Controlling ground-level ozone poses a special challenge because it’s a secondary pollutant — formed in the atmosphere through complex chemical reactions involving nitrogen oxides and volatile organic compounds in the presence of sunlight.
“That’s why ozone levels tend to spike on warm, sunny days,” explains Amy Lu Ryu.
Regulatory agencies typically try to reduce ground-level ozone by limiting nitrogen oxide emissions from industrial sources. Yet predicting the results of these policies remains difficult, since ozone interacts with nitrogen oxides and volatile organic compounds in highly nonlinear ways.
