Recipe for organic haze requires invisible particles
A new study shows that invisible gases seem to be more important than the direct emission of particles from smokestacks and tailpipes. Photo: Gracey Stinson
A new study shows that invisible gases hovering in the atmosphere are important in forming organic haze in both rural and urban areas.
They seem to be more important than the direct emission of particles from smokestacks and tailpipes.
Jose-Luis Jimenez: The particles that you see, for example, coming out of a diesel bus or truck are actually a minor part of the problem. Much more than what you see coming out of a tailpipe is formed later in the atmosphere.
That’s Jose-Luis Jimenez at the University of Colorado. He was co-author of a study published in July 2007 that analyzed data on aerosols from instruments across the northern hemisphere. Aerosols are natural or human-made fine particles suspended in the air above us.
The study showed that these invisible aerosols may be responsible for about two-thirds of organic haze in urban areas and more than 90 percent of haze in rural areas.
This study joins others recently showing the importance of aerosols in human and natural processes. In early 2007, scientists reported a thinning of aerosols, important because aerosols help cool the Earth. Fewer aerosols could mean more warming. This new study on aerosols and organic haze also points to the need to understand aerosols better.
Our thanks today to NASA: explore, discover, understand.
Jimenez told Earth & Sky this study indicates that soot and other tiny particles spewed directly into the air are far less significant than invisible aerosols. These scientists are looking specifically at Volatile Organic Compounds, or VOCs, within aerosols. These invisible VOCs increase the reflection of light back into space. And that reflection, in turn, influences climate change by causing Earth to cool. Because VOCs are not yet well understood, it’s difficult to factor aerosols into climate models. Scientists hope to determine where the majority of VOCs come from in order to reduce their effects.
VOCs are released from gasoline and certain industrial processes, but they’re also produced by trees and other biological sources. Once in the atmosphere, VOCs immediately begin combining chemically with other particles to create organic haze. The haze can then spread over long distances, said Jimenez.
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Press release: Invisible gases form most organic haze in urban, rural areas
Volatile Organic Compounds on Wikipedia
- Our thanks to:*
Jose-Luis Jimenez
Assistant Professor, Department of Chemistry
Cooperative Institute for Research in the Environmental Sciences (CIRES)
University of Colorado at Boulder
