Why Air Quality Matters in Classrooms
  • BenQ
  • 2022-11-30

Do your students feel sluggish during class? It could be the air.

Ever since the start of the pandemic, indoor air quality (IAQ) has become a hot topic in education as poor air quality in classrooms is known to hasten the spread of airborne diseases among students.1 But beyond this, numerous studies have also shown how IAQ can affect academic performance. 

IAQ, which is a blanket term referring to the air conditions in buildings,2 is an important consideration for schools looking to improve their students' grades and lower their chronic absenteeism rate. According to the United States Environmental Protection Agency (EPA), 1 out of 13 students suffer from chronic asthma,3 a leading cause of school absences.4 It's a respiratory condition that's aggravated by poor IAQ.

To prevent these problems, the EPA recommends schools to monitor and regulate different factors affecting IAQ, such as temperature and suspended particles, to name a few. Below, we'll briefly go over each of these factors and see their real impacts on student health and performance.

Effects of poor air quality in classrooms


Slight changes in a classroom’s temperature may seem inconsequential, but studies have shown that even the smallest adjustments to indoor heating and cooling have notable effects on student scores.

Researchers from Harvard University and UCLA reviewing the effects of cumulative temperature on the scores of 10 million PSAT takers have noted that even a 1°F increase in heat in a warm learning environment is enough to drive learning performance down by 1%. And as the temperature rises, the scores get incrementally lower.5 These findings are consistent with other cases showing how high temperatures can impair a person’s motor skills and thinking.6

The same can be said for learning performance in cold environments. A separate case study in New South Wales reveals that a sharp drop in temperature—as a result of cold waves—lowers test scores by 1.2%. The researchers hypothesize that this change occurs because students are suddenly exposed to conditions that their bodies are not accustomed to.7


Much like temperature, indoor humidity also affects student performance. In a study conducted in 2021, a group of undergraduates were tasked to perform learning exercises in different rooms with varying levels of humidity. Researchers observed that if they deviated from the ideal relative humidity—which is 40%—and either lowered the room’s humidity to 20% or raised it to 60%, then the students would begin feeling uncomfortable and distracted. Compared to the experience of students in a room where the relative humidity was kept at 40%, their overall degree of distraction went down by 61.1%, their fatigue decreased by 23.3%, and reading speed by 12.2%.8

Although many may associate a faster reading speed with better student performance, it isn’t necessarily the case. Experts have noted how “speed reading” tends to affect accuracy and comprehension.9 The study results back this up. At 20% humidity, the students’ reading speed may have increased by a few words per minute, but their reading accuracy went down by 1.44%. At 60% humidity, their speed also went up, but their accuracy fell by 0.52%.10

Changes in humidity have also been linked to instances of asthma and asthma-like symptoms. A group of over 500 teachers participated in a study where they were exposed to low (< 30%) and high (> 60%) humidity classroom conditions. Many reported experiencing shortness of breath, wheezing, dry cough, and chest pains in either low or high humidity environments.11

Effects of ideal relative humidity on student performance

Carbon dioxide (CO₂)

Another factor affecting IAQ in classrooms is carbon dioxide (CO2), a very common gas that's a byproduct of our breathing and other natural processes. At low levels, it's safe to inhale, but once the amount surpasses certain thresholds, it begins affecting a student’s concentration and health.

A typical classroom would have a CO2 level of around 400 to 1000 parts per million (ppm), depending on the room’s ventilation and crowdedness. A fully occupied room with inadequate ventilation traps CO2 in the enclosed space and raises its level. Beyond 1000 ppm, students would start getting drowsy and experience other side effects like poor concentration, increased heart rate, and nausea.12

An experiment done in 2016 showed that in rooms where the CO2 levels were increased, cognitive function scores went down significantly. For example, in rooms where the average CO2 concentration was kept at 1400 ppm, the scores dropped by 50%. Activities like gathering and processing new information became more challenging. According to the researchers, on average, an increase of 400 ppm would already be enough to pull cognitive function scores down by at least 21%.13

How different CO2 levels affect health

Volatile organic compounds (VOCs)

As with CO2, the same researchers found that high levels of volatile organic compounds (VOCs) in the air also have negative effects on cognitive performance. They noted a 13% decrease in scores when the room’s total VOC (TVOC) concentration was upped by 500μg/m3.14

VOCs are gaseous compounds that are often found in construction materials, pesticides, and industrial cleaning products.15 Aside from its effects on student performance, exposure to VOCs is also known to cause eye, nose, and throat irritation, fatigue, dizziness and nausea, and in extreme cases, damages to internal organs like the liver, kidney, and the central nervous system.16

One of the most common VOCs is the highly toxic chemical called formaldehyde (CH2O), which can be found in new carpeting and pressed wood furnishings such as chairs and particle boards.17 The United States Occupational Safety and Health Administration considers 100 ppm of CH2O already dangerous as prolonged inhalation of it could lead to severe pulmonary reactions.18 In case there is a high level of CH2O in a classroom, school staff should act quickly to ensure everyone’s safety.

How changes in air quality affect cognitive performance

Particulate matter (PM₂.₅ and PM₁₀)

The last of the common classroom pollutants is “particulate matter”, a term used to describe a mixture of tiny particles suspended in the air. They can be anything from dust, smoke, pollen, or other solid fragments or liquid droplets. Depending on their size, they’re classified as either PM10 (< 10μm) or PM2.5 (< 2.5μm). 

Between the two, health experts consider PM2.5 the bigger health risk19 as it’s been known to infiltrate airways and bloodstreams causing a variety of symptoms like coughing, difficulty breathing, asthma, and irregular heartbeat.20 Long-term inhalation of PM2.5 can also lead to chronic bronchitis, cancer, and heart disease.21

Further research has also linked it to developmental problems in young children.22 Stanford University researchers tested the blood of kids exposed to wildfire smoke and found changes in a gene involved in the development and function of T cells, which are essential in preventing allergies and infections.23

Because of PM2.5’s size and density, it’s easy for the particles to travel far distances and enter classrooms, regardless of the school’s proximity to common sources like factories, open fields, or thoroughfare.24 And for schools that still use chalkboards, both students and teachers are constantly exposed to high levels of PM2.5 in the form of chalk dust. Researchers have noted that chalk use in classrooms with poor ventilation can increase indoor PM2.5 concentration by almost 400%.25 In an effort to regulate PM2.5 levels in classrooms, schools have already begun investing in air filters and ionizers as part of their HVAC system upgrades.

Common sources of particulate matter

Monitoring IAQ with BenQ

The BenQ Board has built-in air quality sensors* that alert teachers via the widget when their classroom’s air quality is below satisfactory. Schools will have the option to customize their widget on the BenQ Board home screen and show only the readings that matter to them. Below is a quick guide explaining what each level means.

From the widget, they can easily see a summary of the real-time status of their classroom’s IAQ levels. In case any of them are high, teachers can immediately improve ventilation by simply opening a window or adjusting the HVAC settings of their classroom. If their BenQ Board is programmed to work with their school’s smart HVAC system, they don’t even need to lift a finger. The BenQ Board can send the live readings to the cloud, which the smart system can then process and use to immediately adjust the room’s air quality.

Understanding the BenQ Board indoor air quality sensor readings

For more information on the BenQ Board air quality sensors, check out our related products below.


  1. Bartzokas, N., et. al, “Why Opening Windows Is a Key to Reopening Schools”, The New York Times, 26 February 2021, https://www.nytimes.com/interactive/2021/02/26/science/reopen-schools-safety-ventilation.html, last accessed 20 September 2022. 
  2. “Introduction to Indoor Air Quality”, United States Environmental Protection Agency, 16, December 2021, https://www.epa.gov/indoor-air-quality-iaq/introduction-indoor-air-quality, last accessed 20 September 2022.
  3. “Why Indoor Air Quality is Important to Schools”, United States Environmental Protection Agency, 9 December 2021, https://www.epa.gov/iaq-schools/why-indoor-air-quality-important-schools, last accessed 20 September 2022.
  4. Balfanz, R. and Byrnes, V., “The Importance of Being in School: A Report on Absenteeism in the Nation’s Public Schools”, Johns Hopkins University School of Education, 16 May 2012, https://new.every1graduates.org/wp-content/uploads/2012/05/FINALChronicAbsenteeismReport_May16.pdf, last accessed 20 September 2022.
  5. Goodman, J, et. al, “Heat and Learning”, National Bureau of Economic Research, May 2018, https://scholar.harvard.edu/files/joshuagoodman/files/w24639.pdf, last accessed 20 September 2022.
  6. Zhong, R., “How Extreme Heat Kills, Sickens, Strains and Ages Us”, The New York Times, 13 June 2022, https://www.nytimes.com/2022/06/13/climate/extreme-heat-wave-health.html, last accessed 20 September 2022.
  7. Baker, J, “Cold snaps hurt student academic results more than heat: study”, 26 October 2021, https://www.smh.com.au/national/nsw/cold-snaps-hurt-student-academic-results-more-than-heat-study-20211025-p592ya.html, last accessed 20 September 2022.
  8. Liu, Chao, et. al, “Influence of indoor air temperature and relative humidity on learning performance of undergraduates”, Case Studies in Thermal Engineering, Volume 28, December 2021, https://www.sciencedirect.com/science/article/pii/S2214157X21006213#, last accessed 20 September 2022
  9. Seidenberg, M., “Sorry, But Speed Reading Won’t Help You Read More”, Wired, 24 January 2017, https://www.wired.com/2017/01/make-resolution-read-speed-reading-wont-help/, last accessed 20 September 2022.
  10. Liu, Chao, et. al, “Influence of indoor air temperature and relative humidity on learning performance of undergraduates”.
  11. Angelon-Gaetz, K., et. al, “Exploration of the effects of classroom humidity levels on teachers’ respiratory symptoms”, International Archives of Occupational and Environmental Health Vol. 89, p. 729-737, 27 January 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4873430/, last accessed 20 September 2022.
  12. “Carbon Dioxide”, Wisconsin Department of Health Services, 15 June 2022, https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm#, last accessed 20 September 2022.
  13. Allen, J., et. al, “Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments”, Environmental Health Perspectives, Vol. 124, No. 6, June 2016, https://dash.harvard.edu/bitstream/handle/1/27662232/4892924.pdf, last accessed 20 September 2022.
  14. Ibid.
  15. “Controlling Pollutants and Sources: Indoor Air Quality Design Tools for Schools”, United States Environmental Protection Agency, 14 September 2022, https://www.epa.gov/iaq-schools/controlling-pollutants-and-sources-indoor-air-quality-design-tools-schools, last accessed 20 September 2022.
  16. “Volatile Organic Compounds' Impact on Indoor Air Quality”, United States Environmental Protection Agency, 26 August 2022, https://www.epa.gov/indoor-air-quality-iaq/volatile-organic-compounds-impact-indoor-air-quality, last accessed 20 September 2022.
  17. Ribeiro, I., et. al, “Formaldehyde levels in traditional and portable classrooms: A pilot investigation”, Journal of Environmental Health, Vol. 78, No. 7, p. 8-44, 1 March 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4876979/, last accessed 20 September 2022.
  18. “1910.1048 App C - Medical surveillance - Formaldehyde”, United States Department of Labor Occupational Safety and Health Administration, https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1048AppC#, last accessed 20 September 2022.
  19. "Particulate Matter (PM) Basics", United States Environmental Protection Agency, 18 July 2022, https://www.epa.gov/pm-pollution/particulate-matter-pm-basics, last accessed 20 September 2022.
  20. “Health and Environmental Effects of Particulate Matter (PM)”, United States Environmental Protection Agency, 30 August 2022, https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm, last accessed 20 September 2022.
  21. “Fine Particles (PM2.5) Question and Answers”, New York State Department of Health, February 2018, https://www.health.ny.gov/environmental/indoors/air/pmq_a.htm#, last accessed 20 September 2022.
  22. Popovich, N., et. al, “See How the World’s Most Polluted Air Compares With Your City’s”, The New York Times, 2 December 2019, https://www.nytimes.com/interactive/2019/12/02/climate/air-pollution-compare-ar-ul.html, last accessed 20 September 2022.
  23. Marill, M., “The Health Effects of Wildfire Smoke May Last a Lifetime”, Wired, 27 June 2019, https://www.wired.com/story/the-health-effects-of-wildfire-smoke-may-last-a-lifetime/, last accessed 20 September 2022.
  24. “Health and Environmental Effects of Particulate Matter (PM)”.
  25. Lin, C., "Effects of Chalk Use on Dust Exposure and Classroom Air Quality", Aerosol and Air Quality Research. Vol. 15, April 2015, https://aaqr.org/articles/aaqr-15-04-oa-0216.pdf, last accessed 20 September 2022.



  • The air quality sensors are available on all models of the BenQ Board Pro.

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