Zeroing in on the chemistry of the air

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We breathe it in and out every few seconds, yet the air that surrounds us has chemical activity and variations in its composition that are remarkably complex. Teasing out the mysterious behavior of the atmosphere’s constituents, including pollutants that may be present in tiny amounts but have big impacts, has been the driving goal of Jesse Kroll’s research.

We breathe it in and out every few seconds, yet the air that surrounds us has chemical activity and variations in its composition that are remarkably complex. Teasing out the mysterious behavior of the atmosphere’s constituents, including pollutants that may be present in tiny amounts but have big impacts, has been the driving goal of Jesse Kroll’s research.

Kroll, an associate professor of civil and environmental engineering and of chemical engineering who earned tenure last year, has been especially focused on studying the role of organic compounds in the air. These carbon-containing compounds include natural emissions from plants as well as products of combustion — everything from gaseous emissions that come from fuel burning in internal combustion engines, to components of soot and other particulate matter that arise from forest fires and other open flames. Such particles are smaller than a micron in diameter but can have outsized environmental effects.

“If you inhale them, they can cause adverse health effects, and they also can affect the Earth’s climate by affecting the amount of sunlight that comes through,” Kroll says.

However, a large fraction of organic particulate matter is not directly emitted into the atmosphere, but instead is formed within the atmosphere from oxidation reactions of gaseous organic species. Understanding such chemical transformations and their effects on atmospheric composition is a daunting task.

 

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Photo via MIT.