Pollen Is Lowering Exam Scores - and the Effect Is Largest in Math and Science

The exam that determines where a Finnish student goes to university, what careers become available, and how their income will compare to their peers - takes place every spring. So does pollen season. That overlap is not a neutral fact, according to a study of 92,280 students and 14 years of data published in the Journal of Epidemiology and Community Health.

A natural experiment built into the calendar

Researchers at Finnish institutions studied every student who sat the national matriculation exam in the Helsinki and Turku metropolitan areas between 2006 and 2020. They retrieved standardized scores across five subjects - Finnish language, History and Social Studies, Mathematics, Physics, and Chemistry - and matched them against daily regional pollen counts for the two plant species that bloom in Finland during the spring exam period: alder (Alnus spp) and hazel (Corylus avellana).

Pollen levels were classified as low (1-10 grains per cubic meter), moderate (10-100), or abundant (100+). On peak days, alder pollen reached 521 grains per cubic meter. Data on air pollution - PM2.5, ozone, nitrogen dioxide - and weather conditions from the Finnish Meteorological Institute were included in the analysis to separate pollen effects from other environmental variables.

In total, 156,059 exam scores were analyzed.

The drop in scores is small per grain, but the scale adds up

An average increase of 10 alder pollen grains per cubic meter of air was associated with a fall in the standardized matriculation score of 0.0034 points. For hazel, the same increase in 10 grains corresponded to a 0.0144 point decline. On the raw exam scale of 0 to 66 points, those translate to reductions of 0.042 and 0.17 points respectively.

These numbers sound modest in isolation. But on a high-pollen day - when counts can exceed 500 grains per cubic meter for alder - the accumulated effect across an exam that might swing admission to a competitive program is not trivial. The score gap between students who got in and those who did not can be narrow enough that the pollen effect matters.

The relationship was not linear. Scores fell on both low-pollen and high-pollen days compared to zero-pollen days, forming a U-shaped curve. That pattern is harder to explain than a simple dose-response relationship and may reflect day-to-day variation in how many students are symptomatic and how severely.

Math, physics, and chemistry took the biggest hit

Both alder and hazel pollen exposure were significantly associated with score drops in quantitative subjects. The researchers suggest this reflects the particular demands of mathematics and science - subjects where a wrong sign, a misread equation, or a moment of lost concentration can cascade into an incorrect answer in ways that essay-based subjects may not penalize as severely.

The pattern differed by sex in some cases. An increase of 10 alder pollen grains was associated with a statistically significant score drop only among female students, corresponding to a 0.0652-point reduction. Hazel pollen's effect on math scores was statistically significant only among males. The study cannot explain these differences; biological variation in allergy prevalence and pharmacological response may be involved, but the data did not include individual allergy histories.

The absent data point

The most significant limitation is that the researchers had no information on which students actually had pollen allergies. Roughly one in five secondary school students is affected by allergic rhinitis - a plausible assumption rather than a measured fact for this cohort. If true, the average score drop observed across all students almost certainly understates the effect on allergic students specifically. The actual impact on a student sneezing through an exam, struggling to concentrate, and potentially sedated by antihistamines could be substantially larger.

"It would be likely that those suffering from pollen allergies would have a higher than average drop in matriculation exam scores," the researchers write - a point that carries weight given how much rides on these results.

What could actually be done

The study's practical suggestions are concrete: schedule high-stakes exams outside peak pollen season where possible, improve real-time pollen forecasting so students can start preventive medication earlier, and raise awareness among healthcare professionals about the academic stakes of poorly managed seasonal allergies. Some countries already provide exam accommodations for students with documented health conditions; pollen allergy is not typically among the recognized categories.

The spring exam calendar is unlikely to change for administrative reasons alone. But knowing that pollen is a measurable performance variable - not an invisible background noise - is the first step toward treating it as one.