Are microscopic particles captured? Doctoral researcher investigates the effectiveness of air purifiers in radiation hazard situations
A year can bring big changes.
Philson-Amanda Aden, 26, started working on her doctoral dissertation in January 2024 at the Department of Physics, University of Jyväskylä. It felt like a major step in her life.
She had completed her master’s thesis the previous autumn, and she liked its topic: the effectiveness of air purifiers in collecting harmful, microscopic particles containing radioactive substances produced in a radiation hazard situation.
Aden got interested in radiation safety as a research topic on a course included in her master’s studies. The topic for her thesis was eventually found from the Radiation and Nuclear Safety Authority, Finland (STUK). Her contact person and supervisor was JYU Professor of Practice Kari Peräjärvi.
The topic was understandable, close to ordinary people and meaningful,” Aden says. “I saw how research could influence practice.”
She was delighted by the chance to continue work on this topic in her dissertation, in the form of applied research. Applied research aims at solving practical problems through new research knowledge.
Aden extended the group of air purifiers being studied by adding an air purifier equipped with a large, activated carbon filter and lengthened the measurement periods to match the maximum duration of indoor sheltering, which is a protective measure in radiation hazard situations. The research involved a differential mobility particle sizer (DMPS) as a new device, which Aden could use to monitor the size distribution of particles in the air of the measurement space.
Radon research can provide information about other substances in a radiation setting
In her dissertation, Philson-Amanda Aden examines three ordinary commercial air purifiers. These purifiers filter air by an electrostatic, activated carbon, or fibric HEPA filter.
Aden examines how well the different purifiers capture radioactive substances that may seep into indoor air during radiation hazard situations. How well do they actually purify the air when people shelter indoors during emergencies and ventilation is shut down?
The gas Aden uses in her research is radon, which occurs naturally in indoor air. Radon is a radioactive substance produced in the crust of Earth, and it is a significant source of radiation exposure in Finland.
Using radon and its particulate decay products, it is possible to estimate the behaviour of particles containing radioactive substances of a certain magnitude released in a radiation hazard situation,” Aden says.
Radon, which is a noble gas, decays into bismuth, polonium and lead isotopes, which are also radioactive. They then form molecular clusters, which can further attach to airborne particles such as dust. In such a case, they are called attached radon progeny.
Currently, Aden is still analysing the measurements. The results can, however, be projected based on the measurements she carried out for her master’s thesis.
“They showed that the air purifiers were effective in collecting attached radon progeny, but not when it came to much smaller unattached radon progeny, which are ultra-fine aerosol particles,” Aden says.
Particle research feels like detective work
Aden is doing her dissertation research at the University of Jyväskylä, under the supervision of Professor Paul Greenlees and Kari Peräjärvi in the research team for nuclear spectroscopy. Greenlees is the Head of the Accelerator Laboratory in the JYU Department of Physics.
Alongside the air purifier analysis, Aden’s dissertation research includes a “process flow chart” on how the analysis proceeds for a radioactive environmental sample – such as an aerosol sample or a sediment sample– received by a research institute.
“The purpose is to describe what is done to the sample, how it must be handled and what kind of methods are used,” Aden explains. “It also includes what methods can yield detailed information on the origin and journey of an individual particle captured by a filter.
This is a bit like detective work.”
When analysing a sample, a range of methods can be used, including gamma-ray spectrometry or X-ray tomography, autoradiography, microscopy or electron microscopy.
Aden finds it important that her research contributes to the operational aspects of radiation safety.
“In radiation safety, anticipation is important so that people know how to act in a real situation,” Aden says. “There must be people who can use the measurement devices, interpret measurement results and make decisions based on the results.”
New Master of Technology programme trains technology and safety experts
Engineering for safety and risk management is the focus of JYU’s new Master of Technology programme.
The programme starts next year and will be unique in Finland. The future graduates will be experts in both engineering and safety and thus capable of looking at technologies based on natural phenomena from the viewpoint of safety and risk assessment.
What makes this new programme so unique?
"Traditionally, education programmes in this field have concentrated on technological aspects,” says Professor of Physics Pekka Koskinen who is in charge of this degree programme at the University of Jyväskylä.
However, the perspective of safety increasingly governs the use of technology. Technological proficiency is no longer sufficient, but it is also important to understand how people use their devices.”
Similarly, it must be understood how a radiation detector works, for instance, and how people act psychologically when using the device. It is important to understand how to use such devices safely. The use of devices has complex multiplicative effects. Finland has so far lacked this kind of programme that integrates technology and safety.”
According to Koskinen, the message from the business community is clear: the labour market has great demand for experts in both technology and safety.
Graduates from the new Master of Technology programme can work as experts, managers and developers of technological safety in companies, research institutes, governmental organisations, and international cooperation projects.
“They can develop technologies for enhanced technical, chemical, biological, and radiation safety. They also know how to protect critical infrastructure, enhance energy security and prevent threats arising from the use of chemical substances, biological pathogens, radioactive substances, nuclear weapons and nuclear materials.”
The degree programme is being offered by the Faculty of Mathematics and Science, University of Jyväskylä. The faculty is concurrently launching a new Master of Technology programme in Statistics and Data Science.
