Campus and Community

“Explain it like I’m 5” kicked off in 2026 with a session dedicated to radiation (which ‘we [human beings] also transmit’)

January 16thupdated on January 21st at 17:06

The first session of the year took place in the Great Hall at Alameda Campus, showcasing the presence of radiation in health, food, and the environment, along with its associated risks, benefits.

“What is radiation used for?” was the question that kicked off the first session of 2026 of the “Explain it like I’m 5”, at 10 a.m. on 14 January in the Great Hall of Instituto Superior Técnico, Universidade de Lisboa. In the front rows, children listened attentively to the presentation, some swinging their feet above the ground, creating an atmosphere marked by curiosity and many questions throughout the morning.

What cannot be seen or smelled began to take shape as Joana Madureira, a researcher at the Centro de Ciências e Tecnologias Nucleares do Instituto Superior Técnico (C2TN), led the conversation. The explanation began with an overview of the electromagnetic spectrum, explaining the differences between ionising and non-ionising radiation, in a way suitable for younger audiences while maintaining scientific rigour.

Examples of radiation in everyday life were emphasized – such as radiology examinations, computed tomography, clinical applications and medical equipment sterilisation processes – showing how radiation is used for the benefit of society. “Radiation is not only associated with danger, but also with concrete benefits in the health sector”, said Joana Madureira, framing these applications in the context of controlled and regulated use.

The researcher also addressed safety issues, exposure limits and protection mechanisms, explaining that “the use of radiation always depends on clear rules and rigorous monitoring”. References to popular culture, such as Hulk, helped to clarify concepts, namely the idea that exposure to radiation causes immediate mutations. “We don’t turn green”, she stressed, adding that the effects always depend on the dose rate and duration of exposure.

The children’s questions guided the session. When talking about natural and artificial sources of radiation, Joana Madureira explained that “we [human beings] also transmit radiation”, reinforcing the idea that radiation is everywhere. “What varies is the amount and duration of exposure, and this difference separates risk from benefit”, she added, noting that negative effects are mainly associated with very high exposure, such as in nuclear accidents.

Audience interest peaked when the conversation shifted to food. Food irradiation was introduced as a method used to eliminate bacteria and fungi, thereby extending the shelf life of fresh produce. Examples included strawberries, raspberries, and onions. In the case of onions, radiation can delay sprouting for several months, while for fruits, it helps maintain quality and prolong preservation. It was emphasised that “irradiated food does not become radioactive and its sale requires specific labeling”, identified by the “Radura” symbol.

Despite the advantages, it was emphasised that the main challenge of this technique is not technical, but rather consumer acceptance. In Portugal, the treatment of food with radiation is not currently permitted, except for aromatic herbs.

Other applications of radiation were highlighted, such as the treatment of contaminated water, environmental decontamination, and the reduction of industrial pollutants. The pre-treatment of agro-industrial waste enabled the extraction of natural phenolic compounds, which possess antioxidant, antimicrobial, and anti-inflammatory properties, illustrating how food by-products can be valued and reused by various industries. “Domestic waste is thus transformed into raw material with added value through radiation”, summarised Joana Madureira.

Once again, children’s curiosity led the conversation to the periodic table with the question, “which element has the most radiation?”. The explanation focused on uranium and clarified that radioactive elements are less numerous than is often thought. The reference to Marie Curie helped frame radiation as the result of scientific discovery, paving the way for new questions about chemical elements and their properties.

The session concluded with the idea that radiation is a part of everyday life and can be used safely and beneficially when it is understood, measured, and applied with proper protection. The balance between accessible language and scientific rigour defined the first session of 2026 of “Explain It Like I’m 5”, which continues to inspire curiosity in young people and the adults who accompany them.