What is that you're breathing now? Is it clean air? Car exhaust? If your air is clean now in July, will it still be clean in December?
Don't worry about it. Chemists are on the case.
Dan Gardner, a recent M.S. Chemistry graduate of the University of Michigan, works in a Maryland Department of the Environment (MDE) air toxics laboratory that monitors air quality throughout the state. MDE works with the federal Environmental Protection Agency to keep an eye on the quality of air across the country.
Part of the work of the Air & Radiation division of the EPA is to record levels of hundreds of air pollutants from locations all over the United States. In particular, the EPA watches levels of six especially important pollutants for which "national standards" - maximum allowable levels - have been established. Carbon monoxide, sulfur dioxide, nitrogen dioxide, dust, lead, and ozone are all regulated.
Air monitoring locations for the EPA and for state-run agencies like the MDE exist all over the country. A team of scientists works at each one to collect samples of the air that we, all of our plants, and all of our livestock breathe. Samples can be collected in a few different forms depending on what they will be used for. Then the samples are carted off to the analysis labs.
|Dan Gardner, an air toxics chemist at the|
Maryland Department of the Environment.
(He's on your side, not the pollution's.)
The team Dan works with is specifically quantifying volatile organic compounds (VOCs) in the atmosphere. These harmful compounds come from a wide number of sources but are most typically used as refrigerants or industrial solvents, or are produced as car exhaust. The EPA compiles the data and offers freely available air quality reports that show how the concentrations of all sorts of airborne pollutants change over time.
What does the work? "I operate two separate gas chromatography/mass spectrometers (GC/MS). I run every sample on both of them and compare the results," Dan writes. The GC/MS is actually two instruments coupled together. Inside the gas chromatograph, a vaporized sample is pushed through a column by an inert carrier gas. The column is made of a material that separates the components of the sample based on some chosen property, most typically polarity. After flying through the gas chromatography column, the sample components reach the next step of the process at different times, which allows them to be detected independently of one another.
In the case of GC/MS, the next step is a mass spectrometer, which ionizes the sample materials and measures their mass. A mass spectrometer was used by the Philae probe last year to answer questions about the origin of water on Earth. Mass spectrometers can also give structural information that is often critical in identifying compounds. GC/MS is a very powerful tandem measurement and is useful across nearly every discipline of chemistry.
The work is all carried out according to procedures written by the EPA. "After the runs, I do a very basic look through the data to make sure it all seems reasonable and does not need to be re-run," Dan writes. He then hands off the test results to another member of the team that is responsible for doing a detailed analysis of the data.
What you see in Dan's winning photo is the preconcentrator set-up for the GC/MS that he works on. "The preconcentrator is the fun part," he writes. "Since the concentrations of the components we are looking for are very small and many of them are volatile, this is used to compile enough in one place to be detected." The samples pass through the traps, which are cooled by liquid nitrogen to temperatures as low as -160 ºC. The cold temperatures force the volatile components to condense as solids or liquids and thereby prevent their escape until they're ready to be injected onto the column.
"We go through a lot of liquid nitrogen. We go through 2/3 to an entire tank each run. Then multiply that by my two instruments and a third one run by a coworker... we go through a lot of liquid nitrogen." All that liquid nitrogen makes for some pretty frosty working conditions as water from the air is frozen onto the pipes. In fact, the ice condensing on the preconcentrator plumbing is one of the largest hang-ups Dan faces in his work. "By the end of a sequence, there's often 5-6 inches of snow and ice. Sometimes it's very powdery and can easily be swept off (or made into snowballs), but some days it's pure, solid ice and we have to take a mallet to it just to close the valve."
The next time you step outside and breathe deep on a fresh, sunny day, send a thought to Dan and his teammates. You never know when all that ice will get the better of them.
First Runner-up: Jessica Gagnon
Jessica performs molecular dynamics simulations on receptor proteins in Dr. Charlie Brooks's lab at the University of Michigan. Research like hers helps to build accurate models of protein-pharmaceutical interactions and is an important part of modern drug discovery.
Second Runner-up: Jordan Boothe
Jordan is a 4th-year graduate student working with Dr. John Wolfe in pursuit of biologically active heterocyclic compounds. He studies palladium-catalyzed reactions with the goal of adding two different nucleophiles across a carbon-carbon double bond.
And finally, by popular demand, here are the remainder of the photo contest entries. Thank you to everyone who entered! Choosing a winner was difficult, and I'm looking forward to the next contest. Thanks again to Sung-Hei Yau and Emily Nelson for helping out with the judging.