What are ozone levels under the shrubbery outside the Lamar Fleming Building on the University of Houston campus? Low, around 15 parts per billion, which made sense as shrubbery and other plants absorb much of the chemical pollutant before it reaches the ground.
How about atop a building a few hundred feet away? Being removed from the ozone-destruction processes at ground level, ozone readers were about 30 parts per billion – far higher than ground readings, but still well below levels considered unhealthy.
Houston used to be known for some of the worst air quality in the nation, resulting from a toxic mix of sunlight with emissions from traffic, chemical plants, refineries and other industrial sources. Nowadays, Houston isn’t even among the Top 10 smoggiest cities.
But that doesn’t mean ozone is no longer a problem, as students in Robert Talbot’s Aerosols and Climate class are discovering.
Equipped with six handheld ozone meters, the class, a mix of graduate students and upper division undergraduates, is getting a field lesson in ozone. Each meter is valued at $5,000 and was bought by the Department of Earth and Atmospheric Science with funds from the UH Provost’s Office. The funding is part of an initiative to boost research experiences for undergraduates.
For Sydnee Landry, an environmental science major who plans to work on environmental policy, the exercise provided an insider’s look at collecting and analyzing data. “I think that’s useful, to get hands-on experience,” she said.
Teaching assistant Travis Griggs downloads the data and returns it to students for analysis. Working with data they collected, rather than that provided by a professor, is more meaningful for students, said Talbot, an atmospheric chemist and professor at UH.
Lower industrial and automotive emissions have significantly lowered ozone levels in Houston, said Talbot, whose research led to the discovery of another variable: Climate change, in the form of stronger sea breeze that brings in cleaner marine air from the Gulf of Mexico, contributes to the drop in high-ozone days in the Houston area.
The project also offers students a look at how dramatically ozone levels can vary. “They see how datasets from different locations can vary, even as close as 100 meters,” Talbot said.
Location matters, said Alyssa Holler, a senior environmental science major. Ozone in the stratosphere – the second layer in the earth’s atmosphere – is a good thing, blocking ultraviolet radiation. At ground level, or the troposphere, “it’s harmful for people and the environment,” she said.