Student’s research will help predict ozone air quality in Philadelphia

Lexie Herdt, a senior majoring in meteorology, enhanced a method to predict ozone levels that will be used in the Philadelphia metropolitan area in summer 2015.  Credit: Ginger KowalchukAll Rights Reserved.

UNIVERSITY PARK, Pa. -- Lexie Herdt has always been fascinated with how the weather impacts people.

“I have family members who have asthma and respiratory issues, and when I was growing up, I saw a lot of family who live in the Philadelphia region affected by high ozone levels,” says Herdt.

Herdt’s passion for understanding weather led her to Penn State’s meteorology program. Now a senior, she is conducting research that will help to more accurately predict ozone levels in the Philadelphia metropolitan area — home to more than 1 million people and her family.  

“When there are high ozone days, hospitals see many more people, especially children and older adults,” says Herdt. “If we can warn people to avoid going out on certain days, it’s going to make a big difference in the long run. Exposure to high ozone levels over multiple days can cause serious lung and health issues.”

In the summer of 2014, Herdt received a Research Experiences for Undergraduates grant though National Science Foundation to conduct research in the Penn State Air Quality Forecast Office with research associate Amy Huff and research assistant William Ryan, both in the Department of Meteorology. For the last 14 years, the office has issued daily forecasts of ozone air quality levels for Philadelphia. Ozone forecasts are provided in the Air Quality Index, a color-coded scale that allows people to understand quickly whether air pollution is reaching unhealthy levels in their communities.

Historically, air quality forecasters have used statistical models as one of the tools to help them prepare ozone forecasts.  However, statistical models became less reliable in recent years as a result of environmental regulations enacted in the early 2000s. The U.S. Environmental Protection Agency required that states reduce the emissions of nitrogen oxides (NOx), chemicals produced during combustion. Ozone is formed when NOx reacts chemically with other pollutants and sunlight in the atmosphere. The statistical models developed in the 1990s were calibrated at a time when NOx levels were higher—so when NOx levels declined in the 2000s, the statistical models became less useful and forecasters could not rely on them to help prepare ozone forecasts for Philadelphia.

Herdt, Huff and Ryan set out to update the statistical models so they could once again be used as a tool to help predict ozone levels—and they did.

After sifting through eight years of 64 meteorological variables, such as daily wind speed levels and temperature, Herdt pinpointed the seven variables most closely associated with high ozone levels. She’s fine-tuning her model this spring through an independent study with Huff, and this summer, she will be implementing her model through an internship with Penn State’s Air Quality Forecast Office.

Helping to improve the accuracy of ozone predictions for millions of people is a significant accomplishment.  The experience of conducting—and presenting—her research is also getting her closer to her dream job of environmental consulting.

“I want to interact with people and work with regulating air quality, emissions, pollution and air quality. I want to be the one communicating to the public and informing them about these issues,” she says.

Herdt presented her research at the 2015 American Meteorological Society conference in January 2015 earning her conference accolades. Out of 198 student presenters, she won the second place Undergraduate Student Poster Award.

“What I really appreciated was how people talked to me about why my research is important,” she says.

Herdt also was approached by several faculty who invited her to consider graduate studies at their university. Even though she hadn’t considered graduate school prior to the conference, Herdt has already applied to work with some of the professors she met.

No matter where her research takes her, Herdt is satisfied with the experience of applying her skills and knowledge to help people.

“This is an issue that impacts people and if I can contribute a piece of research that’s going to help people, I’m happy to have done it,” she says.

Lexie Herdt presented on her research at the 2015 American Meteorological Society conference, where she received a second place prize for undergraduate student research poster. Credit: Lexie HerdtAll Rights Reserved.


Last Updated March 31, 2015