In this insightful Q&A session, Abhisweta Bhattacharjee, Project Officer for RADICAL, interviews RADICAL postdoctoral researcher Dr. Niall O’Sullivan on his journey on improving air quality with advanced sensors. They discuss his work in atmospheric chemistry and air quality, highlighting key challenges and innovations. The conversation explores the real-world applications of his research both within and beyond the RADICAL project.
Could you tell me about your research journey? I know you recently completed your PhD – congratulations on that! Now you’re in your post-doctoral role. Could you tell me about your research, generally?
My research journey began as a research intern with John Wenger during my third year of undergraduate studies. I worked on monitoring pollutants in Cork City, which piqued my interest in atmospheric chemistry. I later applied for PhD funding through the Irish Research Council with the EPA and began my PhD, focusing on volatile organic compounds (VOCs).
My PhD research involved both field measurements and chamber experiments. We conducted a field campaign in Cork City, tracking pollutants and VOCs, identifying sources like solid fuel burning, which was a dominant pollution contributor. In the lab, I explored the oxidation pathways and particle formation potential of two compounds—4-methyl catechol and guaiacol.
Dr Niall O’ Sullivan, Postdoctoral Researcher, University College Cork
Later, I got involved in a separate project called Dublin PortAIR, measuring pollution in the Dublin Port area. This required a lot of fieldwork and high-resolution data collection. After my PhD, I transitioned to a post-doctoral role in the RADICAL project, focusing on testing atmospheric trace gas sensors in the lab, chamber, and ambient environments.
You were involved in building the Irish Atmospheric Simulation Chamber (IASC), the first of its kind in Ireland. What was that experience like for you?
It was an exciting experience to watch the IASC being built. Each time I walked into the lab, I could see the chamber’s progress. But once it was operational, there was some nervousness too, given the size and expense. We had to implement safety checks and make sure it was working as expected. It was challenging to ensure that everything—from airflow to cleanliness—was perfect. There were teething problems initially, but overall, it was exciting to be involved in something so significant.
Could you expand on the tests you’ve been conducting in the chamber related to methane, ozone, and other gases? How does this relate to the RADICAL project?
RADICAL aims to develop electronic sensors to detect trace gases like ozone and radicals such as hydroxyl (OH) and nitrate. These radicals are crucial drivers of atmospheric chemistry but are notoriously difficult to detect due to their short lifetimes.
Read more: How atmospheric radicals transform the air
The Challenge of Measuring Radicals in the Atmosphere
To test the sensors, we simulate these gases inside the IASC. For ozone, we generate it using oxygen and corona discharge, then measure the response of the RADICAL sensors compared to reference monitors. For radicals, it’s more complex because of their reactivity and low concentrations. We’ve tried generating OH radicals through photolysis of hydrogen peroxide and nitrate radicals by reacting ozone and NO2. The sensors have shown some promising responses, but we’re still working on fine-tuning and isolating the signal from interferences.
So, what is the current sensing capacity of the RADICAL sensor when tested in the IASC?
In the chamber, we’ve seen significant interferences from other gases and even light. We’ve had more success with OH radicals in the probe station setup, detecting concentrations around 1 × 109 molecules/cm3. In the IASC, the concentrations we’re generating are approximately 1000 times lower, making detection more difficult. We’re working on differentiating the sensor’s response to radicals from interferences like light and ozone.
The Irish Atmospheric Simulation Chamber
All this work is incredibly detailed and intense. How do you see it benefiting society, and how will these sensors be used in real-world scenarios?
The radicals we’re trying to measure are central to atmospheric chemistry—they initiate reactions that break down pollutants and form particles. Understanding their concentrations can help us better predict how pollutants react and how harmful species form, which affects both human health and climate. For instance, more oxidised compounds and particles can lead to respiratory issues like asthma and COPD. From a climate perspective, these particles scatter or absorb light, influencing global temperatures. So, having a better grasp of radical concentrations can help in both public health and climate change mitigation.
Related: Key benefits and applications of the RADICAL sensor
Looking ahead, what are the next steps in your research within the RADICAL project and beyond?
In RADICAL, we’re focusing on refining our tests in both the probe station and IASC, with the hope of conducting field measurements soon. We want to see if these sensors can perform well in real-world environments. After the project, I’m looking at opportunities that combine my interest in atmospheric chemistry and data analysis, though I don’t have anything set in stone yet.
Reflecting on your research journey, are there any key learnings, challenges, or personal ‘aha’ moments you’d like to share?
One key learning is that research is full of unknowns. You can’t always control the results, and figuring out why something happens is both the challenge and the reward. Perseverance is crucial, especially during a PhD. It’s also important to ask for help and embrace the collaborative nature of research. You’re rarely working in isolation—research is about learning from others and bringing your own expertise to the table.
Dr. Sullivan (2nd row, 2nd from right) with the RADICAL consortium at the third General Assembly in Athens, June 2024
Specifically within the RADICAL project, is there a particular learning or experience you’ll carry forward in your professional life?
Working on RADICAL has been my first experience in a proof-of-concept project. Watching the development from an idea to fabrication and testing has taught me a lot about overcoming obstacles and adapting to challenges. Even with setbacks like Covid, the project has continued, and that resilience and problem-solving approach is something I’ll take with me moving forward.
Finally, is there anything we haven’t covered that you’d like to highlight?
One thing I’ve really enjoyed throughout my research journey is meeting people from all over the world. Research is incredibly collaborative, and you get to engage with a diverse range of perspectives, travel to conferences, and constantly learn from others. That’s been a big part of my experience and something I value a lot.
