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Assessments of Radiological Risks in the Buildings and Surroundings of Federal University Wukari (FUW) Campus, Taraba State, Nigeria

This study assesses the radiological risks of the Federal University Wukari campus in Nigeria by measuring indoor and outdoor terrestrial radionuclide concentrations, finding that while current hazard levels are generally low, buildings with poor ventilation and ground-floor locations exhibit higher radiation levels, suggesting that future campus construction should prioritize upper floors with excellent ventilation.

Original authors: Christopher Mmaduabuchi Odoh, Moses Ejike Onudibia, Yangde Andekwe Ezekiel, Olisa Leonard Osimiri

Published 2026-07-01

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CC BY 4.0

Original authors: Christopher Mmaduabuchi Odoh, Moses Ejike Onudibia, Yangde Andekwe Ezekiel, Olisa Leonard Osimiri

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine the ground beneath our feet and the walls around us are like a giant, invisible battery pack. This battery isn't made of lithium or copper; it's made of tiny, natural radioactive elements that have been there since the Earth was formed. The paper you're asking about is like a "safety inspector" who went to the Federal University Wukari (FUW) in Nigeria to check how much of this invisible energy is leaking out of the campus buildings and the soil around them.

Here is a breakdown of their findings in simple terms:

1. The Invisible Battery Pack (The Radionuclides)

The scientists were looking for three specific "batteries" (elements) that naturally exist in rocks, soil, and building materials:

Potassium-40 (40K): Like a steady, humming background noise.
Uranium-238 (238U): A slightly more active element.
Thorium-232 (232Th): Another natural element found in the earth.

They measured how much of these elements were in the soil outside and inside the university buildings (dorms, offices, labs). Think of it as checking the "radioactive temperature" of the campus.

2. The Findings: Is the Campus Safe?

The researchers used a special handheld device (like a Geiger counter but more advanced) to take readings. Here is what they found:

The "Indoor" vs. "Outdoor" Difference: Just like it's usually warmer inside a house than outside on a cool day, the radiation levels were slightly higher inside the buildings than outside. This is because the walls, floors, and ceilings are made of materials (like concrete and bricks) that contain these natural elements.
- The Ratio: The indoor levels were about 1.3 times higher than the outdoor levels. This is normal and expected for most buildings around the world.
The "Safety Check" (Hazard Index): The team calculated a "Hazard Index." Imagine a traffic light:
- Green (Safe): Below 1.0.
- Red (Danger): Above 1.0.
- Result: The campus was almost entirely Green. The average hazard index was 0.5 indoors and 0.3 outdoors. This means the radiation levels are well below the danger zone. The building materials used are considered safe.
The "Cancer Risk" Meter: They also calculated the "Excess Lifetime Cancer Risk" (ELCR). This is a statistical guess of how many extra cancer cases might happen in a population over a lifetime due to this radiation.
- The results were higher than a very strict safety limit set by the US (USEPA), but they were still lower than the global average.
- Translation: While the risk isn't zero, it's not high enough to cause immediate panic, but it's something to keep an eye on over a very long time (like decades).

3. The "Ventilation" and "Floor" Secrets

The paper discovered two very important "hacks" for reducing radiation exposure, using simple analogies:

The "Second Floor" Advantage:
- The Metaphor: Imagine the ground floor is like the bottom of a swimming pool where the "heavy" radioactive dust settles. The upper floors are like the surface of the water, where the air is cleaner.
- The Finding: The scientists found that buildings on the second floor (or higher) had about 33% less radiation than the ground floor. The elements were simply less concentrated up high.
The "Open Window" Effect:
- The Metaphor: Think of a room with poor ventilation as a stuffy closet where smoke (radioactive gas) gets trapped and builds up. A well-ventilated room is like a house with open windows where the smoke blows away.
- The Finding: Buildings with bad ventilation had radiation levels 48% higher than buildings with good airflow. The "stuffiness" allowed radioactive gases to accumulate.

4. The Conclusion: What Should the University Do?

The paper doesn't suggest closing the university or evacuating anyone. Instead, it offers practical advice for the future, like a recipe for safer construction:

Build Up, Not Down: If they build new staff offices or dorms, they should prioritize upstairs locations. This naturally cuts the radiation exposure by about a third.
Breathe Easy: They must ensure buildings have excellent ventilation. Good airflow acts as a shield, flushing out the radioactive gases that build up in stuffy rooms.
The Verdict: The campus is currently safe for students and staff. The radiation levels are within acceptable limits, but by building smarter (higher up and with better airflow), they can make the environment even safer for the long haul.

In a nutshell: The Federal University Wukari is a safe place to study and work. The "invisible battery" in the ground and walls is active, but not dangerous. However, if the university wants to be extra careful for the next 50 years, they should build their new offices upstairs and make sure the windows open wide.

Technical Summary: Assessments of Radiological Risks in the Buildings and Surroundings of Federal University Wukari (FUW) Campus, Taraba State, Nigeria

Problem Statement
The study addresses a critical knowledge gap regarding terrestrial gamma radiation exposure within the Federal University Wukari (FUW) campus, a facility housing approximately 30,000 staff and students. While previous studies in Taraba State, Nigeria, have identified regions with elevated terrestrial gamma dose rates—particularly near uranium deposits and mining sites—no systematic assessment had been conducted specifically within the university's built environment. Given that Taraba State has been linked to a high incidence of cancer cases and that the local geology (Bima sandstones and continental grits) contains natural radioactive materials, the authors sought to determine the radiological conditions of the campus. The study aimed to evaluate indoor and outdoor activity concentrations of primordial radionuclides ( $^{40}\text{K}$ , $^{238}\text{U}$ , and $^{232}\text{Th}$ ), calculate associated radiological hazard parameters, and statistically test the hypothesis that no significant relationship exists between radionuclide activity concentrations and radiological risks.

Methodology
The assessment was conducted across the 200-hectare FUW campus, covering academic buildings, staff quarters, laboratories, and open fields.

Instrumentation: Measurements were performed using a portable NaI(Tl)/BGO gamma survey meter (Compact Gamma Surveyor by GF Instruments, 2016) and a Garmin GPS for geolocation.
Measurement Protocol: In-situ measurements were taken both indoors (in lecture halls, offices, and hostels) and outdoors (open fields, roadsides). The detector was positioned 1 meter above the ground. Five readings were taken at each location for 5 minutes each to ensure statistical reliability, and averages were calculated.
Data Conversion: Raw concentrations were converted to activity units ( $\text{Bq/kg}$ ) using IAEA conversion factors.
Risk Evaluation: The study calculated several radiological parameters:
- Radium Equivalent Activity ( $R_{eq}$ ): To assess the uniformity of gamma dose rates.
- Hazard Index (HI): To evaluate gamma radiation risk relative to safety limits.
- Absorbed Dose Rate (ADR): Measured in $\text{nGy/h}$ .
- Annual Effective Dose (AED): Estimated using occupancy factors (0.8 for indoor, 0.2 for outdoor) and conversion coefficients.
- Excess Lifetime Cancer Risk (ELCR): Calculated using a risk factor of 0.05 and an average lifespan of 55 years.
Statistical Analysis: Pearson correlation coefficients were used to analyze the relationship between radionuclide activities and radiological parameters. Comparative analyses were also performed based on building floor levels (ground vs. upper floors) and ventilation quality.

Key Results

Activity Concentrations:
- Indoor: Mean concentrations were $785.3 \pm 30.7 \text{ Bq/kg}$ for $^{40}\text{K}$ , $44.5 \pm 2.1 \text{ Bq/kg}$ for $^{238}\text{U}$ , and $37.2 \pm 1.9 \text{ Bq/kg}$ for $^{232}\text{Th}$ .
- Outdoor: Mean concentrations were $561.1 \pm 30.4 \text{ Bq/kg}$ for $^{40}\text{K}$ , $35.7 \pm 1.5 \text{ Bq/kg}$ for $^{238}\text{U}$ , and $31.1 \pm 1.4 \text{ Bq/kg}$ for $^{232}\text{Th}$ .
- Comparison: Indoor $^{40}\text{K}$ and $^{238}\text{U}$ levels exceeded global averages, while $^{232}\text{Th}$ levels were below global averages.
Radiological Parameters:
- Radium Equivalent ( $R_{eq}$ ): Mean indoor and outdoor values were $158.2 \pm 6.4 \text{ Bq/kg}$ and $123.3 \pm 4.5 \text{ Bq/kg}$ , respectively, both well below the safety limit of $370 \text{ Bq/kg}$ .
- Absorbed Dose Rate (ADR): Average indoor ADR was $76.4 \pm 3.1 \text{ nGy/h}$ , and outdoor was $59.3 \pm 2.1 \text{ nGy/h}$ . The indoor-to-outdoor ratio was 1.3.
- Hazard Index (HI): Average indoor HI was 0.5 and outdoor was 0.3, indicating low risk as both are below the unity threshold.
- Annual Effective Dose (AED): Mean indoor AED was $0.37 \pm 0.02 \text{ mSv/y}$ , and outdoor was $0.07 \pm 0.00 \text{ mSv/y}$ . The total campus AED ( $0.45 \text{ mSv/y}$ ) is below the Nigerian public dose limit ( $1.0 \text{ mSv/y}$ ) and the global average ( $0.52 \text{ mSv/y}$ ).
- Excess Lifetime Cancer Risk (ELCR): The mean total ELCR was $1.23 \pm 0.05 \text{ mSv}$ . While this exceeds the USEPA threshold of $0.106 \text{ mSv}$ , it remains below the global average of $1.45 \text{ mSv}$ .
Influencing Factors:
- Floor Level: Upper floors exhibited approximately 33–35% lower activity concentrations and radiological parameters compared to ground floors.
- Ventilation: Buildings with poor ventilation showed significantly higher radiological parameters (up to 48% higher ADR) compared to well-ventilated structures.
Statistical Correlations: A strong positive correlation ( $p=0.01$ ) was found between indoor radionuclide activities and all radiological hazard parameters. Outdoors, $^{40}\text{K}$ showed a strong correlation, while $^{238}\text{U}$ and $^{232}\text{Th}$ showed moderate correlations.

Significance and Claims
The authors assert that the study provides the first baseline database for terrestrial radiation exposure at FUW, serving as a critical reference for legislators, environmental health authorities, and university management.

Safety Assessment: The study concludes that the current radiological conditions pose "negligible" immediate health risks to the university community, as hazard indices and dose rates generally fall within international and national safety limits.
Long-term Implications: While immediate risks are low, the authors note that the ELCR values exceed the USEPA threshold, suggesting a potential for stochastic health effects (cancer) over long-term exposure periods.
Practical Recommendations: Based on the data, the authors recommend that future construction at the campus prioritize upstairs locations and excellent ventilation. They claim these measures could reduce radiological hazards by approximately 33% (via floor elevation) and 48% (via ventilation), significantly mitigating the accumulation of radioactive gases and daughter products.
Future Work: The paper explicitly calls for further research to assess radiological risks in the campus's water sources and surrounding towns to provide a more comprehensive radiological profile for the region.

The study rejects the null hypothesis, confirming a significant statistical relationship between primordial radionuclide activities and associated radiological risks within the campus environment.

1. The Invisible Battery Pack (The Radionuclides)

2. The Findings: Is the Campus Safe?

3. The "Ventilation" and "Floor" Secrets

4. The Conclusion: What Should the University Do?

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