Associations between school characteristics and children’s health

Determinants of the health status of the children varied significantly among the participating countries, thus all the analysed associations between the school environment and children’s health status were corrected for country, as well as for age, gender, parental smoking and living density at home. For a summary of the statistically significant (p<0.05, i.e. where the probability of chance is less than 5 percent) or borderline significant (p<0.1, where the probability of chance is less than 10 percent) associations between school and classroom characteristics and the health status of children, click on the link below.


Additional information

Tables A5 and A6 summarise the statistically significant (p<0.05, i.e. where the probability of chance is less than 5 percent) or borderline significant (p<0.1, i.e. where the probability of chance is less than 10 percent) associations between school and classroom characteristics and children’s health status.

Table A5 Significant associations between school characteristics and children’s health status (corrected for age, gender, parental smoking at home, living density at home and country)

School characteristics

Health outcomes

OR (95% CI)

Reconstructed <5 years

Doctor-diagnosed aeroallergen allergy

Doctor-diagnosed house dust mite allergy

Doctor-diagnosed pollen allergy

1.95 (1.20–3.18)**

2.04 (1.22–3.41)**

2.09 (1.05–4.18) *

Traffic heavy/very heavy vs. light/moderate

Any allergic symptoms

Earache

Depression

1.14 (0.98–1.33)~

1.22 (0.99–1.51)~

1.16 (0.99–1.36)~

Existence of school yard

Hay fever (protective effect)

Social withdrawal (protective effect)

0.27 (0.11–0.65) **

0.34 (0.16–0.71)**

Existence of green space around the school

Diagnosed allergy to medicines (protective effect)

 

0.71 (0.54–0.92)*

 

Industry in the vicinity

Regular day/night cough

Earache

Upper respiratory complications

1.39 (1.04–1.85)*

1.43 (1.09–1.87)*

1.22 (0.97–1.55)~

Table A6 Significant associations between classroom characteristics and children’s health status (corrected for age, gender, parental smoking at home, living density at home and country)

Classroom characteristics

Health outcome

OR (95% CI)

Floor level (per level)

House dust mite allergy diagnosed (negative effect)

Pollen allergy diagnosed (negative effect)

0.87 (0.77–0.99)*

0.89 (0.79–1.0)~

Street orientation

Chronic cough for more than 3 months

1.46 (1.05–2.05)*

Crowdedness

(<1.5 m2/person)

Any chronic cough

Chronic day/night cough

1.28 (1.04–1.57)*

1.30 (0.99–1.71)~

Wooden floor

Attention deficit

Food allergy

1.31 (1.03–1.66)*

1.26 (0.98–1.63)~

Plastic floor

Any doctor-diagnosed allergy

Doctor-diagnosed pollen allergy

Animal fur, feather allergy diagnosed

1.18 (0.99–1.41)~

1.35 (1.07–1.69)*

1.37 (1.06–1.69)*

Stone/concrete floor

Attention deficit

Social withdrawal (reserve)

1.99 (0.92–4.30)~

1.54 (0.93–2.55)~

Wall whitewashed

Regular morning cough

1.30 (1.00–1.70)*

Water-soluble paint

Anxiety

Blocked/runny nose

1.39 (1.07–1.79)*

1.13 (0.99–1.30)~

Water-resistant paint

Doctor-diagnosed asthma ever

Asthma treatment in the last 12 months

Any doctor-diagnosed allergy

1.32 (1.05–1.65)*

1.39 (1.05–1.82)*

1.18 (1.00–1.39)*

Wallpaper

Irritability

1.71 (1.21-2.41)**

Wall renewed within 1 year

Regular morning cough

Allergic oedema

Dry cough at night

 

1.39 (1.11–1.73)**

1.53 (1.06–2.21)*

1.21 (0.98–1.50)~

Wall renewed within 2 years

Allergic oedema

Conjunctivitis

1.48 (0.98–2.23)~

1.34 (0.99–1.82)~

Openable windows

<2 m2

Any type of chronic cough

Regular morning cough

Allergic oedema

1.30 (1.06–1.58)**

1.32 (1.02–1.71)*

1.62 (1.03–2.55)*

Windows not opened every break

Any type of chronic cough

Regular morning cough

Regular cough with phlegm

Wheeze in the last 12 months

Dry cough at night

Doctor-diagnosed asthma ever

Asthma treatment in the last 12 months

Doctor-diagnosed house dust mite allergy

Doctor-diagnosed ragweed allergy

Doctor-diagnosed animal fur/feather allergy

Blocked/runny nose

Anxiety

Social withdrawal (reserve)

1.37 (1.15–1.62)***

1.27 (1.02–1.57)*

1.43 (1.15–1.79)**

1.35 (1.14–1.60)***

1.36 (1.12–1.67)**

1.29 (1.01–1.63)*

1.29 (0.96–1.74)~

1.30 (1.02–1.66)*

1.43 (1.01–2.02)*

1.53 (1.11–2.11)**

1.16 (1.00–1.35)*

1.43 (1.11–1.83)**

1.49 (1.11–2.00)**

Windows usually closed during classes due to noise

Any type of chronic cough

Fatigue

Anxiety

1.38 (1.03–1.84)*

1.36 (0.98–1.87)~

1.49 (0.94–2.37)~

Morning cleaning

Asthma treatment in the last 12 months

Woken up by wheeze

1.41 (1.02–1.96)*

1.37 (0.94–1.98)~

Evening cleaning

Dry cough at night

Any doctor-diagnosed allergy

Doctor-diagnosed house dust mite allergy

Doctor-diagnosed pollen allergy

Conjunctivitis

Anxiety

Hay fever

1.34 (1.01–1.78)*

1.36 (1.07–1.74)*

1.40 (1.02–1.93)*

1.40 (0.99–1.97)~

1.56 (1.08–2.25)*

1.59 (1,10–2.29)*

1.57 (1.01–2.44)*

 

-

 

Cleaning once a day (vs. twice a day)

Upper respiratory complications

1.40 (1.11–1.77)**

Use of vacuum cleaner

Sinusitis

Woken up by wheeze

Hay fever

1.48 (1.03–2.14)*

1.48 (0.96–2.26)~

1.46 (0.94–2.28)~

Use of broom

Regular cough with phlegm

Sinusitis

Fatigue

Depression

1.43 (1.06–1.94)*

1.41 (1.00–1.98)~

1.35 (1.11–1.65)**

1.36 (1.13–1.64)**

Use of mop

Conjunctivitis

Fatigue

Depression

1.69 (1.16–2.46)**

1.34 (1.06–1.69)*

1.37 (1.10–1.70)**

Windows not opened during cleaning

Regular cough with phlegm

1.90 (1.20–3.00)**

Blackboard vs. white board

Asthma treatment in the last 12 months

Sinusitis

2.33 (1.07–5.07)*

2.08 (1.08–4.00)*



Statistically significant associations are not necessarily the most important. Below we discuss those associations that can be considered important from a public health point of view.

School location

An industrial facility in the close vicinity of the school was found to have an adverse effect on children’s respiratory health (shown by the increased prevalence of children with a chronic cough, earache, upper respiratory tract complications and decreased lung function results). The distribution of the participating schools in relation to traffic density by country is shown in Table 1.

Figure 8

Relationship between concentrations measured inside the classrooms and outside the schools

shows that the primary source of NO2, and to some extent also of PM10, is outdoor air pollution. In the case of both NO2 and PM10, there is a significant decreasing trend in the measured indoor concentrations the higher the floor level

(Figure 12

Mean concentrations of NO2 measured in classrooms on different floors of the school building

and

Figure 13).

Mean concentrations of PM10 measured in classrooms on different floors of the school building

In the case of NO2, the decrease is from ground floor to fourth floor, while in the case of PM10 the decrease is from below the ground floor to the fourth floor.

 

Figure 14

Mean indoor concentrations of NO2 in classrooms by traffic density, street orientation and floor level

shows that the mean concentrations of NO2 measured in the classrooms depend on traffic density in the close vicinity of the school, the floor level of the classroom, and whether the classroom faces the street or the schoolyard. Indoor PM10 concentrations were also higher on the lower floors than the higher floors, especially in areas with high traffic density (see link below).

 


Additional information

Indoor PM10 concentrations were higher on the lower floors than the higher floors, especially in areas with high traffic density

(Figure A1).

Mean indoor PM10 concentrations in classrooms by traffic density, orientation and floor level

 



There is a significant decreasing trend in the prevalence of doctor-diagnosed pollen and house dust mite allergies the higher the floor level. Figures showing the prevalence of children with such allergies in classrooms on various floor levels can be found by clicking on the link below.


Additional information

Figure A2

Prevalence (%) of children with a doctor-diagnosed pollen allergy by classroom floor level

shows the prevalence of children with a doctor-diagnosed pollen allergy by classroom floor level, and

Figure A3

Prevalence (%) of children with a house dust mite allergy by classroom floor level

shows the prevalence of children with a house dust mite allergy by classroom floor level.

 



Classroom crowdedness

The mean floor space in this study was 2.02 m2/child. The distribution of classrooms with floor space of less than 2 m2/child by country can be seen on the link below.


Additional information

Table A3 Distribution of classrooms with floor space of less than 2 m2/child by country

Country

>2 m2/n

<2 m2/n

Total

Albania

0 (0.00%)

34 (100.00%)

34

Belarus

35 (94.59%)

2 (5.41%)

37

Bosnia and Herzegovina

16 (40.00%)

24 (60.00%)

40

Hungary

22 (52.38%)

20 (47.62%)

42

Italy

25 (65.79%)

13 (34.21%)

38

Kazakhstan

22 (55.00%)

18 (45.00%)

40

Serbia

30 (78.95%)

8 (21.05%)

38

Slovakia

29 (93.55%)

2 (6.45%)

31

Tajikistan

19 (55.88%)

15 (44.12%)

34

Ukraine

24 (60.00%)

16 (40.00%)

40

Total

222 (59.36%)

152 (40.64%)

374



Overcrowding in the classrooms (i.e. floor space of less than 2 m2/child) resulted in a significant increase in the measured indoor concentrations of several pollutants, including CO2, benzene, toluene and PM10

(Figure 15,

Association between CO2 concentration and overcrowding in classrooms

Figure 16

Association between indoor concentrations of benzene and toluene (µg/m3) and overcrowding in classrooms

and

Figure 17).

Association between PM10 concentration (µg/m3) and overcrowding in classrooms



Classroom occupancy is an important parameter in all countries. The prevalence of children with chronic cough symptoms is significantly higher in overcrowded classrooms. A figure showing the potential health risks of overcrowding can be found on the link below.


Additional information

Figure A4

Prevalence (%) of children with chronic cough symptoms in classrooms with floor space less than or greater than 1.5 m2 per child

shows the adverse impacts of overcrowding, as the prevalence of children with chronic cough symptoms was significantly higher in classrooms with floor space of less than 1.5 m2/child.



Floor covering

The use of plastic flooring was found to be associated with a significantly increased risk of doctor-diagnosed allergies

(Figure 18)

Prevalence (%) of children with various types of diagnosed allergy in classrooms with and without plastic flooring

and decreased lung function in some countries.



On the other hand, a higher prevalence of children with symptoms of depression was found in classrooms with a simple stone or concrete floor, although after adjustments these associations were no longer statistically significant.

Wall covering

The use of water-resistant paint is associated with a significantly increased risk of doctor-diagnosed asthma and allergies in the participating countries

(Figure 19).

Prevalence (%) of children with asthma or asthmatic symptoms in classrooms with walls painted with water-resistant paints

 


Additional information

Figure A5

Prevalence (%) of children with a diagnosed allergy in classrooms with walls painted with water-resistant paint

shows the prevalence of children with a diagnosed allergy in classrooms with and without walls painted with water-resistant paint.

 



Concentrations of the measured volatile organic compounds (benzene, ethylbenzene, xylenes and toluene) were all significantly higher in classrooms with walls that had been renovated in the last two years. Concentrations were similar in classrooms that were renovated either one or two years ago.


Additional information

Figure A6

Mean concentrations of VOCs in classrooms with walls renewed in the last two years or earlier

shows mean concentrations of VOCs in classrooms with walls renewed in the last two years or earlier.

 



Children in classrooms with recently painted walls were at significantly higher risk of regular morning coughing than children in classrooms with walls painted more than two years ago.


Additional information

Figure 7

Prevalence (%) of children with a chronic cough or allergic oedema in classrooms with walls renewed within one year

shows the prevalence (%) of children with a chronic cough or allergic oedema in classrooms with walls renewed within one year



Ventilation

 


Additional information

In classrooms with openable windows bigger than 2 m2, there were significantly fewer children with chronic cough symptoms (protective effect)

(Figure A8).

Prevalence (%) of children with chronic cough symptoms in classrooms with openable windows smaller or bigger than 2 m2

If the association is reversed, openable windows smaller than 2 m2 per classroom were associated with a significantly increased risk of chronic cough symptoms.

 



Openable windows do not in themselves protect children from chronic coughing. In classrooms where windows were not opened every break, significantly more children suffered from a chronic cough than in those classrooms that were ventilated more frequently.


Additional information

In classrooms in which windows were not opened every break, significantly more children suffered from chronic cough symptoms than in those ventilated more frequently

(Figure A9

Prevalence (%) of children with a chronic cough in classrooms in which windows were either opened or not opened during the break


and

Figure A10).

Prevalence of children with psychological symptoms in classrooms in which windows were either opened or not opened during the break

 



The prevalence of chronic coughing was 50 percent higher in classrooms where the windows were not opened every break compared to classrooms where the windows were opened every break, and the prevalence of regular coughing was even higher.

Children in classrooms with windows that were regularly opened even during teaching time were significantly more protected from chronic coughing than children in classrooms where the windows could not be kept open during classes due to outdoor noise.

Time and means of cleaning

Most of the investigated asthmatic and allergic symptoms occurred more frequently in classrooms that were cleaned in the evening (87.7 percent of classrooms). Technical staff therefore need to be advised to open the windows after cleaning the classrooms in order to reduce the level of emissions from cleaning products in the indoor air.

Conclusions

 

  • The large database containing information on 7,860 children from 388 classrooms in 100 schools in 10 countries provided a unique opportunity to study a wide variety of school indoor and outdoor environments; to measure outdoor and indoor concentrations of several air pollutants; and to investigate the associations between the school environment and children’s health.
  • Indoor concentrations of NO2 and — to a lesser extent — PM10 originated from outdoor pollution sources (mainly traffic), while volatile organic compounds and formaldehyde were mainly emitted by indoor sources.
  • The health status of children from the various countries was assessed and compared. It was observed that asthmatic symptoms and doctor-diagnosed allergies were significantly less frequent in the four new SEARCH II countries than in the six SEARCH I countries. This observation is in line with earlier findings on the difference between East and West Germany in the 1990s and can be explained by the “Western lifestyle”.
  • The results of the spirometry tests confirmed that the great majority of children still have normal respiratory function. The challenge is to maintain this situation in the future and to further improve the environment in which they live.
  • The extensive database made it possible to identify several statistically significant associations between the school environment and children’s health. Some associations may be accidental and difficult to interpret, but most provide useful information and well-documented facts that can be used to determine new interventions in order to ensure a healthier school environment and better respiratory health for children.
  • The results allow us to identify some obvious examples of effective interventions: overcrowding in classrooms should be avoided; windows should be opened every break, and some should even be kept open during classes as well; plastic (PVC) flooring and water-resistant paints should be avoided; and schools should not be built alongside busy roads or in areas that are heavily polluted from other sources.

 

 

 
Ministero Dell'ambiente Italian Trust Fund