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Air purification reduces children’s morbidity in the daycare

Published on 12.9.2024
Tampere Universities
Kuvituskuva viruksista tummalla taustalla.
Photo: E3-hanke
The multidisciplinary E3 Excellence in Pandemic Response and Enterprise Solutions (E3) project, which focuses on preventing pandemics and finding out the different routes of infectious diseases, starts publishing final results after three years of work. The most significant outcomes are, for example, the results from the daycare study performed in four different daycare centres in the city of Helsinki. In the daycare centres, where the air was cleaned with air purifiers, children’s morbidity decreased by 18 percent.

E3 is a multidisciplinary co-innovation project looking for research-based solutions to prevent the spread of pathogens. The project aims to harness science and technology to create effective countermeasures to prevent spreading of infectious diseases. 

The goal has been that during the current pandemic and before the emergence of the next pandemic, scientifically proven technical solutions would be available to reduce the spread of pathogens in places where people meet. The E3 project ends at the end of October 2024. 

Morbidity was reduced in the daycare centres with the help of air purification 

Within the last two years, a crossover study was performed in four daycare centres in Helsinki to determine the significance of the airborne transmission route of pathogens and to study the effectiveness of air cleaning in reducing infections among children in daycare. 

The daycare centres included in the study had working ventilation systems and the indoor air quality was generally at a good level. The study lasted for two years, during which a year-long intervention was implemented in two daycare centres at a time, increasing the amount of clean air in the premises with air purifiers to reduce airborne exposure. 

Based on the risk assessment, the placement, number and power of the air purifiers were chosen in such a way that the amount of clean air in the rooms more than doubled on average. During the intervention, indoor air quality and children's illnesses were monitored and analyzed. 

Data about children's illnesses was collected in electronic diaries in November and April in the winters of 2022–2023 and 2023–2024. All children attending the daycare were invited to participate (n = 262), and consent was obtained from 88 guardians resulting in 51 subjects for the final analysis. 

The study found a significant reduction of 18 percent in morbidity without implementing other infection mitigation strategies beyond air purification. The findings highlight growing scientific evidence that common respiratory infections are spread through the air.  

Since ventilation and air purification can only affect particles traveling in the air stream, the results highlight the possibility of airborne transmission of the spread of infectious pathogens through the air, and air purification as a preventive measure. 

The importance of these results is emphasized when considering the high probability of other transmission routes, such as contact and droplet infections, among daycare children. Furthermore, the placebo had no effect on the results when the subjects were between 1 and 6 years old. 

The study was led by research doctors Enni Sanmark and Ville Vartiainen from the Helsinki University Hospital and Piia Sormunen, Industry Professor (Built environment & Civil engineering) from the Tampere University. Senior researcher Inga Ehder-Gahm from Technical Research Centre of Finland, VTT was responsible for dimensioning the air cleaners and the technical implementation of the intervention. 

Several leading companies participated in the collaboration. They brought e.g. diagnostics, air cleaning, ventilation and sensor technology. The research bodies in the kindergarten study were Helsinki University Hospital (HUS), Tampere University, Tampere University of Applied Sciences, Finnish Meteorological Institute, Finnish Institute of Occupational Health, VTT Technical Research Centre of Finland and University of Helsinki. The E3 companies included in the daycare study were Granlund, Air0, Halton Group, Lifa Air, Alme Solutions, Inspector SEC (ISEC), Airlyse, Filterpak, Roche Diagnostics and Tamlink. 

The goal is to fight pandemics and epidemics 

The research results found in the E3 project have already been utilized, for example, in research and preparedness work related to the spread of bird flu (H5N1 virus). 

E3 has primarily studied different pathways of pathogens and viruses, virus control and detection methods that can be used to find solutions to keep indoor air clean and safe in offices, public spaces, and vehicles. 

The main goal has been to develop solutions that allow the various functions of society to continue without interruption and people can continue to move and live safely despite epidemics and pandemics. 

The final results and findings of the project will be presented in more detail at the Tackling Pandemics final seminar at the University of Helsinki on October 30, 2024. 

About the project 

E3 is one of the largest co-innovation projects between companies and research organizations ever launched in Finland. The project has a budget of 12 million euros and a duration of three years. The project is jointly financed by Business Finland and the participating companies. 

The participating companies are Afry Oy, Air0 Oy, Airlyse Oy, Alme Solutions Oy, AW2 Architects Oy, Biomensio Oy, Cleamix Oy, Filterpak Oy, Granlund Oy, HUS, Halton Oy, Inspector SEC Oy, Kone Oyj, Lumikko Oy, Ramboll Finland Oy, Olfactomics Oy, Royal Caribbean Group Oyj, EG Finland Oy, Rune & Berg Oy, Roche Diagnostics Oy, Vetrospace Oy, Helsinki University Hospital and Lifa Air Oy. 

The participating research organisations are Tampere University, VTT Technical Research Centre of Finland, Finnish Meteorological Institute, University of Helsinki, Finnish Institute of Occupational Health, Tampere University of Applied Sciences and Finnish Institute for Health and Welfare. 

More information at project website www.pandemicresponse.fi 

Contact persons: 
Piia Sormunen 
Tampere University 
piia.sormunen [at] tuni.fi (piia[dot]sormunen[at]tuni[dot]fi), +358 50 476 6731 

Enni Sanmark 
Helsinki University Hospital, HUS 
enni.sanmark [at] hus.fi (enni[dot]sanmark[at]hus[dot]fi), +358 40 844 6940 

Inga Ehder-Gahm 
VTT Technical Research Centre of Finland 
inga.ehder-gahm [at] vtt.fi (inga[dot]ehder-gahm[at]vtt[dot]fi), +358 40 542 7043 

Jari Erkkilä 
E3 Project Coordinator, Tamlink 
jari.erkkila [at] tamlink.fi (jari[dot]erkkila[at]tamlink[dot]fi), +358 40 513 6917 

Earlier publications from Yle (Finnish Broadcasting Company): https://yle.fi/a/74-20062381