PhD research finds poor classroom air quality hinders learning

For her PhD research, Dr Lara Tookey investigated how the indoor environment in Aotearoa New Zealand primary schools affects how well students can think and learn.

Her research focused on two aspects: temperature and carbon dioxide (CO₂) levels.

“I went to several schools in different parts of the country and at different times of the year to measure these factors. I used special equipment to track temperature and CO₂, and also watched how often windows were opened. I also asked teachers and students about how comfortable they felt in the classrooms. Finally, I tested students' concentration, reasoning and memory using online games and activities,” Dr Tookey explains.

She found that when classrooms were at comfortable temperature, had fresh air and low CO₂ levels, students performed better on cognitive tests. However, when CO₂ levels were high or the temperature was too hot or too cold, students didn't do as well.

“Basically, stuffy and uncomfortable classrooms make it harder for kids to think!”

Some ways schools can create optimal learning environments, according to Dr Tookey’s research, include improving ventilation practices by opening windows regularly, improving insulation to reduce temperature fluctuations, installing effective heating and cooling systems in classrooms and implementing continuous monitoring systems for CO₂ levels and temperature.

Understanding the effects of these simple measures can empower teachers to take immediate action to improve classroom conditions.

To understand how temperature and indoor air quality affect cognitive function, Dr Tookey conducted a series of tests in classrooms under three different environmental conditions: baseline representing the typical classroom environment, increased temperature with open windows and increased temperature with closed windows.

“Under each condition, students completed a series of online cognitive tests, designed to assess various aspects of cognitive function, including concentration, reasoning and short-term memory. By comparing student performance on the cognitive tests across the three conditions, I could isolate the effects of temperature and ventilation on cognitive function. This controlled approach allowed me to determine whether warmer temperatures, with or without adequate ventilation, had a positive, negative, or no discernible effect on students' ability to concentrate, reason and remember information.”

Dr Tookey says research suggests a comfortable temperature range for learning environments is typically between 18-24°C. However, this range should be considered a guideline, not a rigid rule.

“In colder regions of New Zealand, particularly during winter, the higher end of this range (closer to 24°C) might be more appropriate. Conversely, in warmer, subtropical areas, especially during summer, the lower end of the range (closer to 18-20°C), or even slightly lower, might be more comfortable. Adapting the temperature within this range based on the specific climate and season is key to creating an optimal learning environment. While maintaining a temperature within the recommended range is important, individual preferences should also be considered. Allowing for some flexibility and providing options for personal temperature regulation, such as layers of clothing, can enhance comfort and wellbeing.”

Dr Tookey’s findings can be used to inform future new classroom design or the redesign of existing ones.

“Architects and engineers can prioritise natural ventilation, thermal comfort and indoor air quality in their designs to create healthier and more conducive learning environments from the outset. Additionally, policymakers can use my research to develop evidence-based guidelines and policies for indoor environmental quality in schools. This could include setting standards for ventilation rates, CO₂ levels and thermal comfort, as well as providing resources and support for schools to implement these standards.

“I also believe it’s important to get everyone involved – teachers, students and school management – to make these changes happen and create healthier learning spaces for kids.”

A surprising finding from Dr Tookey’s research was that a 2015 survey of 40 Auckland primary schools found that only 40 per cent of teachers opened windows during winter teaching sessions. A follow-up survey in 2024 revealed a decrease in window opening, with only 30 per cent of Auckland teachers reporting opening windows during teaching sessions across all seasons.

“Another surprising finding was the significant influence of time of day on cognitive performance. Students consistently performed better on cognitive tests in the afternoon compared to earlier in the day. This suggests that scheduling more demanding cognitive tasks for later in the school day could potentially leverage these higher performance levels. However, this needs to be carefully balanced against the potential for increased fatigue later in the day. Thoughtful scheduling that considers both the potential benefits of peak cognitive performance and the risks of student fatigue is crucial for maximising learning effectiveness.”

Dr Tookey is an accomplished educator and consultant with over two decades of international experience in tertiary education, specialising in the intersection of indoor environmental quality and cognitive performance. Her career reflects a deep commitment to teaching excellence, research innovation and the transformative power of education across diverse cultural contexts, including South Africa, Singapore, Scotland and New Zealand.