all Daniel Jacob stories

Dust from Asia invades North America

70652986 — Mon, 26 Mar 2007 06:28:24 -0400

On the dustiest days in the western United States, 40 percent of the grime blows in from Asia. And fine particles can travel all the way around the world from Africa's Sahara Desert. These unwanted visitors show up in a new model of dust imports developed by researchers from Harvard and the National Aeronautics and Space Administration (NASA). The findings have important implications for air pollution and climate change.

The Asian dust invasion is heaviest in the western states in spring. It moves on into the eastern U.S., but in much lower quantities. The traveling grime is mobilized by strong winds blowing over deserts or dry lakes and streambeds. "Most of the dust is from natural sources and falls out close to its source," notes Daniel Jacob, a professor of atmospheric chemistry and environmental engineering at Harvard. "But fine dust can be transported over long distances: from Asia to North America, and from North Africa to Florida, and all the way around the world to Canada and the U.S."

The grit is a health problem. A study done by other investigators, at the Harvard School of Public Health, concludes that an increase of particulate air pollution increases the risk of early death for people with diabetes, chronic obstructive lung disease, congestive heart failure, and inflammatory ailments like rheumatoid arthritis and lupus. Fine mineral dust is so damaging because it can penetrate much deeper into the lungs than larger particles.

Jacob worked with graduate student T. Duncan Fairlie and research associate Rokjin Park to build a computer model for estimating the impact of dust from Asia. They tested the model's accuracy with measurements from a NASA aircraft mission over the Pacific led by Jacob in 2001. The results were compared with dust records from Japan, various Pacific Islands, and air quality observing stations in the United States.

The model simulates the highs and lows of dust flow. Following the largest flow in spring, things quiet down in summer. Then a second, less active peak blows dust around in the fall. Winter is quiet.

North African dust imports peak during summer months in Florida and along the Gulf Coast. It adds haze in the Great Smoky Mountains, the Appalachians, and other East Coast locations.

Brighter model for global warming

50443248 — Wed, 25 Jul 2007 11:08:56 -0400

To environmental chemist Scot Martin, chemistry is a way of understanding the Earth and some of its most pressing problems.
From global warming to heavy metal pollution in groundwater, Martin, named Gordon McKay Professor of Environmental Chemistry last July, is using the tools of chemistry to shed light on how natural processes interact with human activities to affect the environment.

Warming world would see fewer summer breezes

50443248 — Wed, 25 Jul 2007 15:53:13 -0400

A group of climate researchers has shown that a warming globe over the next 50 years could result in fewer appearances of summer's cleansing winds over the Northeast and Midwest United States, resulting in worsening air pollution in the regions.
Loretta J. Mickley, a research associate at the Division of Engineering and Applied Sciences; Daniel J. Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering; B. D. Field of the Division of Engineering and Applied Sciences; and D. Rind of the Goddard Institute for Space Studies in New York examined the impact of increasing greenhouse gas concentrations on pollution events in the United States through 2050.