Ruijie Zhu joined HOBEL as a new PhD assistant

Ruijie shares her experiences, first impressions, and future goals as she joins EPFL and the Human-Oriented Built Environment Lab. Let's see what she shares.

• You just arrived at the EPFL Fribourg - what are your first impressions?

I first arrived in Fribourg on a rainy and gloomy day, but my mood was excited, unaffected by the weather; perhaps it was because my heart was filled with anticipation for the brand-new doctoral journey in this city. Afterwards, I took a short walk around the city to experience the local lifestyle and pace. My impression was that the people here are friendly, peaceful, orderly, and respectful of boundaries—making it a very comfortable place to be. And yes, I also felt warmly welcomed by the team members, and they kindly showed me around our base (EPFL's Fribourg campus). It felt quite unlike any other university I'd been to before – more compact and refined, with colorful walls that gave me the impression of being in a playground, haha.

• Can you tell us more about your career in academia?

I received my Bachelor's and Master's degrees in Environmental Engineering and Environmental Science, respectively, from Nanjing University in 2022 and 2025. In fact, it was during my Master's degree that my academic career in science really began, and I received professional training in the properties of micro-/nanoparticles (especially micro(nano)plastics) and their toxicological interactions with organisms (especially plants) and the environment. More importantly, these research experiences sparked my interest in exploring the health impacts of fine particles on human beings, which must be inspiring and meaningful!

• What are you most excited about your appointment at the Human-Oriented Built Environment Lab?

I’m really excited that I have joined a team that has been doing and will continue to do research that I have always been curious about and wanted to do--focusing on indoor air quality and human-oriented research. Moreover, the team is composed of distinguished members from diverse disciplines and cultural backgrounds. Personally, as I transition into a field somewhat different from my previous work, I look forward to learning from each member and strengthening my ability to tackle scientific challenges through a multidisciplinary perspective. I am also excited to grow and progress together with the team.

• What will your research focus on over the coming year?

I will start focusing on exploring the sources and dynamics of ultrafine particles (UFPs) in indoor environments, applying my accumulated experience of the properties of nanoparticles (some of which overlap with ultrafine particles in size range). Meanwhile, I may integrate my toxicology knowledge and big-data analysis into UFP-related work to better reveal and understand the impacts on human health.

• What inspires you about the built environment of the future and its research schemes?

What inspires me is the urgent need to create healthier indoor environments where we spend so much of our lives. While we know that PM_2.5 poses a significant health threat, research is now uncovering an even finer and potentially more dangerous pollutant: UFPs. They are more numerous and may be more harmful, but we know little about how they behave dynamically inside our buildings. My specific hope is to elucidate how these tiny particles move and change in different indoor conditions. By understanding this, we could ultimately contribute to designing indoor spaces that better protect our health.

• Whenever you are not doing research, what are you interested in?

My hobbies really revolve around sports and music. On the sports side, I love long-distance running and hiking. They help me get close to nature, relax, stay healthy, and train my perseverance. I also enjoy badminton and have some foundation in tennis (feel free to reach out for a game!). And since we're in Switzerland, I definitely want to start learning to ski. As for music, I often put on my headphones in my spare time and lose myself in my favourite singers and bands. It never fails to lift my mood and keep me energized.