Smarter Kids and Fewer Sick Days Through Clean Air

If you read our other blog posts you might already know that around 90% of the people on our planet are breathing dirty air, and that an estimate of 7 million people die every year due to it [1]. You might also know that nearly half a million babies died in 2019 due to dirty air [2].

There is little doubt that dirty air is bad for both children and adults, but all this might be a bit abstract for a parent. This blog post will mainly look at how the air can impact the development of children and how the air quality relates to absenteeism in school, for both children and teachers.

Impact on Children’s Cognitive Development

There are multiple studies indicating that poor air quality can have a negative impact on a child’s cognitive development.

In a study [3] carried out in Los Angeles and surrounding counties, it was found that for every increase 2.5µg/m3 PM2.5 during the pre-teen and teen years, one performance IQ point was lost. Performance IQ is related to one’s ability to solve new problems, and it is to a greater extent controlled by brain function, as opposed to something you can learn [4].

In a report by Unicef [5] it is mentioned how air pollution can impact memory and verbal and non-verbal IQ. Furthermore, it is mentioned that test scores and average grades (GPA) have been shown to be negatively impacted by air pollution exposure. Also prenatal exposure is discussed. A study they mention showed that prenatal exposure to air pollution resulted in a four-point drop in IQ by the age of 5. In addition to this study, also [6] shows that exposure during fetal life can have negative consequences on brain development. Air pollution seems to haunt us throughout our whole lives, from foetus to when old (especially if you are male) [7].

One of the studies referenced in the Unicef report looked at 2,715 children between 7 and 10 years old in schools in Barcelona [8]. The study concludes Children attending schools with higher traffic-related air pollution had a smaller improvement in cognitive development.. However, the editor comments:
Importantly, these findings do not prove that traffic-related air pollution causes impairment of cognitive development. Rather, they suggest that the developing brain may be vulnerable to traffic-related air pollution well into middle childhood, a conclusion that has implications for the design of air pollution regulations and for the location of new schools. [8]

In [9] researchers looked at children when they were 9 months old and then 3 years old. They observed that exposure to high levels of NO2 was associated with lower verbal ability at the age of 3. They also looked at indoor damp or condensation (which can be a hint for poor ventilation), and observed that it was associated with reduced verbal ability. Furthermore, they looked at exposure to second hand smoking, which perhaps unsurprisingly was also associated with lower verbal ability at the age of 3 years.

Researchers have also looked at the commute to school and found that PM2.5 and black carbon (BC) exposure was associated with diminished growth of working memory [10].

The findings seem fairly consistent - dirty air is harmful. We therefore believe it is worth paying attention to the air quality in the environments where our children spend a large portion of their early lives. We can not eliminate air pollution exposure, but at least it can be reduced through awareness and taking actions if needed.

Also IQAir has looked at this topic and written an article Can clean air increase child IQ?. They found some of the same references as we, but also some others. We recommend you to have a look if you are curious about this topic.

Cleaner Air Leads to Fewer Sick Days

Perhaps more concrete than air pollution’s impact on cognitive development is how it affects the number of sick days. This can naturally also in turn impact a child’s development, since day care (or school) is supposed to be a place where children both have fun and learn new things.

One study [11] found that with air purification non-attendance was decreased by 55% in a preschool. Another experiment, also in a Swedish preschool, showed a reduced sick-leave of at least 22.5% [12].

A school in Finland also observed reduced sick leave [13], as well as improved concentration, after installing air purifiers. However, we couldn’t find any numbers for how much.

In London, following the release of The Mayor’s School Air Quality Audit Programme [14], a number of schools followed the recommendation to get air purifiers. 56 teachers were surveyed after getting air purifiers, and more than half of them reported having noticed a decrease in sick leave among themselves and children [15].

There is also some support for reduced absenteeism among teachers with better air quality, for instance [16] found such a connection. We will in the future look into absenteeism at workplaces and its relation to air quality. We suspect there will be more research about that than teachers specifically.

The Västra Götaland Regional Council in Sweden has observed large variations in sick leave among preschools and theorize that this might be due to differences in indoor air quality [17]. This is expanded on [18] in Läkartidningen, the official Journal of the Swedish medical association. The doctors point out that the indoor air often has more particles than the outdoor air (in Sweden), both because of indoor activities and that small particles from traffic get in. Children are said to be especially vulnerable to air pollution. The doctors theorize that indoor pollution acts as an additional burden on children’s immune system, which risks making it less able to cope with viruses.

Important to note is that many of the above references have links to companies with commercial interests. Sadly, it is hard to find studies without any ties to industry. We found at least two double-blind studies [19] [20] supporting health benefits of air pollution reduction through the usage of air purifiers though. Note that also the European Commission did a research project called SINPHONIE looking at improving air quality in schools and kindergartens. See the final report for a deep dive into this topic. They also cover absenteeism, and on top of [11], they reference Association between substandard classroom ventilation rates and students’ academic achievement, Indoor air microbes and respiratory symptoms of children in moisture damaged and reference schools and The Impact of School Building Conditions on Student Absenteeism in Upstate New York. All in support for that there’s a link between air quality and absenteeism.


We believe there’s enough supportive evidence for it being worth to make sure that the indoor air quality is good (below WHO limits), and if not, take action. We’ll try to write a new post in the future more focused on what one can do, but meanwhile, some suggestions:

  • Especially if you are pregnant, have a baby or young child, pay attention to outdoor air pollution and consider an air purifier if pollution is high. It appears that air pollution may be more harmful the younger the child is.

  • Consider asking your preschool to get an air purifier if it is located close to heavy traffic or the air quality seems low. Some preschools are already aware of this, for instance Eduwings have a strategy in place. Sadly it appears that mainly private expensive preschools are using air purifiers, at least in China [21].

  • Reduce indoor activities that can lead to increased air pollution. For instance high temperature cooking, usage of candles or other indoor combustion. A well maintained kitchen hood and ventilation system can mitigate air pollution build-up. But you can also just open your window when cooking with high temperature.

  • Prefer walking in the forest or through a park rather than along roads with high traffic.

  • Install an app, such as IQAir’s Air Visual. It can help you to know when air pollution is high, so that you can reduce air pollution exposure. For instance by staying indoors the worst days, preferably in a room with an air purifier. Or at least avoiding heavy outdoor exercise.

  • Minimize second hand smoking, especially if you are pregnant, have a baby or young children.

We hope you enjoyed the article. As always, reach out to your doctor or other official services if you have any concerns about your or your families health.


[1] “9 out of 10 people worldwide breathe polluted air, but more countries are taking action,” World Health Organization. May 2018, [Online]. Available:

[2] “Impacts on newborns,” State of Global Air. [Online]. Available:

[3] C. A. Y. Wang Pan AND Tuvblad, “Socioeconomic disparities and sexual dimorphism in neurotoxic effects of ambient fine particles on youth iq: A longitudinal analysis,” PLOS ONE, vol. 12, no. 12, pp. 1–15, Dec. 2017, doi: 10.1371/journal.pone.0188731.

[4] C. Boyd-Barrett, “Teen exposure to air pollution could reduce iq levels long term,” California Health Report. Jan. 2018, [Online]. Available:

[5] N. Rees, “Danger in the air,” UNICEF South Asia. Jan. 2017, [Online]. Available:

[6] M. Guxens et al., “Air pollution exposure during fetal life, brain morphology, and cognitive function in school-age children,” Biological Psychiatry, vol. 84, no. 4, pp. 295–303, 2018, doi:

[7] “Air pollution linked to "huge" reduction in intelligence,” UN Environment. Oct. 2018, [Online]. Available:

[8] M. A. A.-P. Sunyer Jordi AND Esnaola, “Association between traffic-related air pollution in schools and cognitive development in primary school children: A prospective cohort study,” PLOS Medicine, vol. 12, no. 3, pp. 1–24, Mar. 2015, doi: 10.1371/journal.pmed.1001792.

[9] E. Midouhas, T. Kokosi, and E. Flouri, “Outdoor and indoor air quality and cognitive ability in young children,” Environmental Research, vol. 161, pp. 321–328, 2018, doi:

[10] M. Alvarez-Pedrerol et al., “Impact of commuting exposure to traffic-related air pollution on cognitive development in children walking to school,” Environmental Pollution, vol. 231, pp. 837–844, 2017, doi:

[11] K. G. Rosén and G. Richardson, “Would removing indoor air particulates in children’s environments reduce rate of absenteeism — a hypothesis,” Science of The Total Environment, vol. 234, nos. 1 – 3, pp. 87–93, Aug. 1999, doi: 10.1016/S0048-9697(99)00266-1.

[12] A. Jagemo, “Renare luft gav friskarebarn på enögla förskola,” Enköpings-Posten, pp. 6–6, Mar. 2019, [Online]. Available:åFörskolaEnköpingsPostenMars2019.pdf.

[13] “Air-related symptoms no longer trouble in seppo school,” Genano. [Online]. Available:

[14] “The mayor’s school air quality audit programme,” Mayor of London. [Online]. Available:

[15] “London schools improve results and reduce sick leave among children and staff after installation of air purifiers,” Mynewsdesk. Blueair, Sep. 2019, [Online]. Available:

[16] J. Ervasti et al., “School environment as predictor of teacher sick leave: Data-linked prospective cohort study,” BMC Public Health, vol. 12, no. 1, p. 770, Sep. 2012, doi: 10.1186/1471-2458-12-770.

[17] “Bättre inomhusluft kan minska sjukfrånvaron bland förskolebarn,” Västra Götalandsregionen. Oct. 2017, [Online]. Available:

[18] P. Gustafsson et al., “Poor indoor air quality may be behind the high rate of sick leave in preschool,” Lakartidningen, vol. 114, Jul. 2017, [Online]. Available:

[19] R. E. Reisman, P. M. Mauriello, G. B. Davis, J. W. Georgitis, and J. M. DeMasi, “A double-blind study of the effectiveness of a high-efficiency particulate air (hepa) filter in the treatment of patients with perennial allergic rhinitis and asthma,” Journal of Allergy and Clinical Immunology, vol. 85, no. 6, pp. 1050–1057, Jun. 1990, doi: 10.1016/0091-6749(90)90050-E.

[20] S. Weichenthal et al., “A randomized double-blind crossover study of indoor air filtration and acute changes in cardiorespiratory health in a first nations community,” Indoor Air, vol. 23, no. 3, pp. 175–184, 2013, doi:

[21] N. Dandan, “City kindergartens battle to have air purifiers installed,” Global Times. Jan. 2016, [Online]. Available: