Article

09 April 2004

Chasing Asian smoke across Texas and New Mexico

Forrest M. Mims III

On 27 March 2004, soot from Asian fires fell across New Mexico and Texas. NAAPS model smoke forecast courtesy of the Naval Research Laboratory. Click image to enlarge.

Beginning in early March, farmers across Southeast Asia began burning their fields in preparation for planting. The smoke from these fires became so dense it was easily seen in satellite images.

The density of the smoke and the weather conditions combined to send much of the smoke eastward over the Pacific Ocean. Several days after leaving Asia, much of the smoke crossed The West coast of the United States, where much of it fell out as microscopic particles of soot.

On some days in March 2004, the rain of soot covered most of the Western U.S., including Texas.

This was an opportunity too good to miss. When the Naval Research Lab forecast a new invasion of Southeast Asian smoke to arrive over New Mexico and Texas at the end of March, I loaded up the old pickup with science gear and headed West.

I took along some sophisticated instruments on this trip. But none were as successful as the Model USS dust and smoke sampler, a device specifically engineered to capture microscopic particles of dust and smoke.

Please don't tell any scientists you know that USS is the abbreviation of Ultra Simple Sampler. You might as well know that the instrument is also known as a Model UCS (Ultra Cheap Sampler).

The Model USS is a black plastic tube. One end is flattened and bent at an angle. This leaves a narrow, rectangular opening. A two-inch wide piece of clear tape is placed over the opening.

Air entering the open end is deflected by the tape out openings on either side. Particles in the air that don't get deflected stick to the tape. At least that's what I hoped would happen.

Model USS Ultra Simple Sampler taped on the hood of a pickup truck for initial pilot test. The sticky side of the tape faces toward the air flow. Note the microscope slide inserted in the gap between the tape and the output of the sampler. The slide is used as a substrate for the tape sample after a collection run. Click image to enlarge.

The original plan was to mount the Model USS onto a strip of hook and loop fastening material on the hood of the pickup. But that meant dust stirred up by the turbulent wake of passing cars and trucks might contaminate the samples.

So I simply held the Model USS out the window for fixed distances while cruising along the highways of West Texas and New Mexico. If a car or truck approached, I simply placed the air sampler inside the cab until the vehicle was well away.

After a specific distance, usually 10 miles, I stopped the truck and downloaded the data. This was done by inserting a sterile microscope slide between the exposed loop of tape and the USS opening. I then inspected the sample through the eyepiece of a microscope.

So what did I see when the samples were inspected? Space has run out for this week's column, so be sure to read next week's installment. I'll let you know the surprising results of my quick smoke trip to New Mexico.

Forrest M. Mims III and his science are featured online at http://www.forrestmims.org/.

This feature was originally published in Forrest Mims's weekly science column in the Seguin Gazette-Enterprise, Seguin, Texas. The column is written for a general audience.