Wildfire, Soil Emissions Increasing Air Pollution in Remote Forests

Satellite Data Reveals Increase in Nitrogen Dioxide Levels in California’s Forests

A recent study conducted by the University of California, Davis, published in the journal Environmental Research Letters, has found that nitrogen dioxide levels in remote forest areas of California have been increasing. This increase is likely due to wildfires and soil emissions.

The Impact of Nitrogen Dioxide

Nitrogen dioxide is a short-lived atmospheric pollutant that plays a significant role in the formation of ozone and particulate matter. These pollutants can have detrimental effects on human health, causing respiratory issues and asthma, as well as harming plants and crop yields.

The researchers analyzed surface and satellite concentrations of nitrogen dioxide between 2009 and 2020. They discovered that while levels decreased by 2-4.5% per year in urban areas across California, rural concentrations remained relatively constant, and remote forests experienced an alarming increase of approximately 4.2% per year.

According to bio-micrometeorologist Ian Faloona, the senior author of the paper, “Forested areas show a steady, rapid rate of increase in summer. The trend is alarming.”

To conduct the research, scientists analyzed surface nitrogen dioxide levels collected by the state and NASA’s Aura satellite. They categorized different areas based on surface temperature, soil moisture levels, and land types such as urban, forests, croplands, scrublands, and barren areas with little vegetation.

New Sources to Consider

The study revealed that controls on internal combustion engines and other fossil fuel emitters have successfully reduced nitrogen dioxide levels in urban areas where most air pollution monitors are located. However, continuous satellite data showed that this effect is not mirrored in rural areas and remote forests. In these regions, wildfires and emissions from agricultural soils, particularly those with fertilizer use, are correlated with an increase in nitrogen dioxide levels.

These findings have important implications for future policy decisions as regulators aim to further decrease the pollutant. While current emission management actions continue to target fossil fuel emissions, it is crucial to address other sources that have been overshadowed by traditional internal combustion sources.

According to Faloona, “Soils, and wildfires in particular, are really going to become steerers of the ship of our air pollution. We have to put a lot of effort into curtailing the effects of wildfires and understanding better our emissions from agricultural soils.”

Additional Research Needed

Areas with high fertilizer use can be a significant source of nitrogen dioxide emissions due to microbial competition with crops for nitrogen, resulting in the generation of gaseous nitrogen compounds. However, further research is required to fully understand the exact role of wildfires and soil in the increase of ambient nitrogen dioxide levels.

The authors of the study emphasize the need for additional research to better comprehend the environmental dependence of soil and wildfire emissions. They state, “Our results point to opportunities for different sets of policies and technologies to assist in reducing nitrogen dioxide concentrations in rural and economically disadvantaged areas of California.”

Yurun Wang from the Department of Land, Air and Water Resources, now at Hong Kong Polytechnic University, and former UC Davis professor Benjamin Houlton, currently at Cornell University, also contributed to this research.

The research was funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture.

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SDGs, Targets, and Indicators

1. SDG 3: Good Health and Well-being

   • Target 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination.
   • Indicator: Nitrogen dioxide levels in remote forest areas and their impact on respiratory issues and asthma in humans and harm to plants and crop yields.

2. SDG 11: Sustainable Cities and Communities

   • Target 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.
   • Indicator: Decrease in nitrogen dioxide levels in urban areas across California.

3. SDG 13: Climate Action

   • Target 13.2: Integrate climate change measures into national policies, strategies, and planning.
   • Indicator: Increase in nitrogen dioxide levels in remote forests due to wildfires and emissions from agricultural soils.

4. SDG 15: Life on Land

   • Target 15.1: By 2020, ensure the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems and their services.
   • Indicator: Increase in nitrogen dioxide levels in remote forests and its impact on the environment.

Table: SDGs, Targets, and Indicators

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Source: ucdavis.edu

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