Supplementary Information

Indoor and outdoor air concentrations of volatile organic compounds and NO2 in schools of

urban, industrial and rural areas in Central-Southern Spain.

Florentina Villanueva (a),(b)*, Araceli Tapia (c), Sonia Lara (a), Mariano Amo-Salas (d)

aAtmospheric Pollution Laboratory, Research Institute for Combustion and Atmospheric

Pollution, University of Castilla-La Mancha, Camino de Moledores s/n, 13071 Ciudad Real,

Spain Florentina.vgarcia@uclm.es; Sonia.Lara@alu.uclm.esbCastilla-La Mancha Science and Technology Park, Paseo de la Innovación 1, 02006 Albacete,

SpaincPhysical Chemistry Department, Faculty of Chemical Science and Technologies, University of

Castilla-La Mancha, Avenida Camilo José Cela s/n Araceli.tapia@uclm.esdDepartment of Mathematics, Faculty of Medicine, University of Castilla La Mancha, Camino de

Moledores s/n 13071, Ciudad real, Spain. mariano.amo@uclm.es

* Author to whom correspondence should be addressed:

Phone: +34 926295300. E-mail: Florentina.VGarcia@uclm.es

Fig. S1. Location of rural, urban and industrial areas (B) in Spain (A).

Valverde

Las Casas(B)

(A)

Rural areas

Urban area

Industrial area

Fig. S2. Chromatogram registered from a sample collected in the school 1 in the industrial area.

Text S1. Multiple linear regression

Table S1. Results of multiple linear regression

Pollutants variable β S.E p-Value R2

Acetaldehyde marble tile/wooden 1.84±0.63 0.007 0.291Years school1(11-20/1-10) 2.92±1.33 0.035

ACR+ATN Both/blackboard 14.41±3.98 0.001 0.284Propanal marble tile/wooden 0.32±0.14 0.034 0.679

Both/blackboard 0.41±0.23 0.085Urban/rural -1.03±0.18 0.000Industrial/rural -0.73±0.18 0.000

Benzaldehyde Students (11-20/1-10) 0.75±0.27 0.010 0.117Pentanal Urban/rural -2.16±0.36 0.000 0.554

Industrial/rural -1.79±0.36 0.000p-Tolualdehyde Recently painted -0.37±0.17 0.042 0.119n-Hexane ceramic tile/wooden 2.88±0.71 0.000 0.471

Whiteboard/blackboard 1.96±0.81 0.021n-Heptane Whiteboard/blackboard 13.1±5.81 0.031 0.286

ceramic tile/wooden 11.17±5.11 0.037n-Nonane street/playground 7.58±1.56 0.000 0.477

Both/blackboard 3.98±1.37 0.007n-Decane street/playground 9.05±2.56 0.001 0.373

Both/blackboard 6.63±2.26 0.006n-Undecane Both/blackboard 6.68±1.65 0.000 0.418

Students(21-30/1/10) -2.47±1.06 0.026n-Dodecane Both/blackboard 7.12±2.22 0.003 0.238n-Tridecane Floor (first floor/ground floor) -8.14±2.10 0.001 0.331

Classroom (primary /kindergarten) 7.01±2.09 0.002Cyclohexane ceramic tile/wooden 14.74±5.97 0.019 0.160Benzene Outdoor concentration 0.82±0.14 0.000 0.501Styrene street/playground 14.02±2.92 0.000 0.412Trimethylbenzene

Timber cladding/painted wall 3.37±1.29 0.013 0.171

Limonene Years school (11-20/1-10) 50.12±10.93 0.000 0.442Whiteboard/blackboard 21.90±9.06 0.022

NO2 Outdoor concentration 0.865±1.51 0.000 0.584Timber cladding/painted wall 9.80±3.17 0.004Students(21-30/1/10) 4.72±2.11 0.032

β, partial regression coefficient; SE, standard error, p-Value, significant level (set at< 0.05); R 2, coefficient of determination

Pollutant sources are diverse, some pollutants come from outdoor sources, some from

indoors, and other from both outdoor and indoor sources, therefore it is not easy to

establish a relation between VOCs and different factors. We have used multiple linear

regression analysis based on the indoor and outdoor concentrations and the qualitative

parameters taking into account the responses to the questionnaire (see Table 1). Table

S1 shows the significant factors affecting the indoor concentrations of certain VOCs and

NO2. Only the variables of the questionnaire that were included in the final model

obtained by stepwise procedure have been included. In order to understand the table it is

important to know the meaning of the different parameters. β is the partial regression

coefficient that gives the type and magnitude of relation between the pollutant and the

variable given, if β is positive means that when the variable increases, also the

concentration of the pollutant increases and if β is negative the relation is inverse,

therefore, when the variable increases, the level of the pollutant decreases. The

inclusion of categorical variables has been done using dummy variables and β stands for

the relation between the category of the numerator with respect to the denominator in

the concentration of the pollutant. For instance, if β is positive the presence of the

category of the numerator increases the levels of the studied pollutant with respect to the

presence of the category of the denominator. For benzene, the variable included in the

model is outdoor concentration, the relation is positive with a coefficient of

determination (R2) of 0.501. Thus the 50 % of the variability of the levels found of

benzene can be explained by the outdoor concentrations. Also NO2 is positive

associated with the outdoor concentrations. The statistical analysis shows a significant

and positive association between n-alkanes (n-hexane, n-heptante, n-nonane, n-decane,

n-undecane and n-dodecane) and limonene with the type of board what suggests that the

use of whiteboard (category of the numerator) has a certain impact on the levels of these

pollutants in the classrooms.

The location of classrooms appeared to affect the indoor levels of n-nonane, n-decane

and styrene. Those classrooms located street facing had higher levels of these pollutants.

This happened only in two schools of the industrial area.

The timber cladding used in the walls appeared to positively affect the indoor levels of

trimethylbenzene and NO2. No association was found with the type of floor covering.

Finally the levels of benzaldehyde, n-undecane and NO2 were associated with the

number of students in the classrooms, thus more concentration of n-undecane and NO2

were found in those classrooms with the highest number of students (21-30).

Table S2. Spearman correlation coefficients of VOCs and NO2 in the classrooms of kindergarten and primary in the schools of the rural, urban and industrial arearural 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

1.Formaldehyde 1.002.Acetaldehyde ,699* 1.003.ACR+ATN 0.01 -0.23 1.004.Propanal ,790** ,706* 0.18 1.005.Benzaldehyde 0.12 0.37 -0.18 0.20 1.006.Pentanal ,825** ,643* -0.19 ,748** 0.27 1.007.p-Tolualdehyde -0.22 -0.10 -,65* -0.28 -0.25 -0.15 1.008.Hexanal 0.51 0.53 -0.26 0.45 -0.20 ,734** -0.01 1.009.n-Pentane 0.31 0.42 -0.25 0.11 -0.03 0.29 0.01 0.27 1.0010.n-Hexane 0.03 0.06 0.13 -0.26 0.28 0.04 -0.36 0.02 0.17 1.0011.n-Heptane 0.29 0.10 -0.04 0.25 -0.48 0.45 0.24 0.54 0.30 0.02 1.0012.n-Octane 0.34 0.12 0.20 0.38 -0.01 0.37 -0.07 0.01 0.46 -0.07 ,615* 1.0013.n-Nonane 0.36 0.38 0.37 ,636* 0.13 0.22 -0.29 -0.11 0.36 -0.38 0.09 ,692* 1.0014.n-Decane 0.00 0.22 0.46 0.41 -0.08 -0.15 -0.17 -0.20 0.23 -0.29 -0.01 0.27 ,692* 1.0015.n-Undecane -0.02 0.17 ,662* 0.45 -0.09 -0.15 -0.47 -0.08 -0.20 -0.25 -0.12 0.01 0.53 ,818** 1.0016.n-Dodecane 0.20 0.17 ,690* 0.53 -0.17 0.06 -0.23 -0.05 0.02 -0.28 0.13 0.32 ,629* ,846** ,776** 1.0017.n-Tridecane 0.38 0.48 -0.21 0.28 -0.37 0.29 0.13 0.54 0.44 -0.41 0.20 -0.02 0.20 0.19 0.11 0.21 1.0018.Cyclohexane 0.21 0.03 0.08 0.27 -0.50 0.29 0.27 0.33 0.32 -0.13 ,930** ,748** 0.33 0.19 0.01 0.28 0.12 1.0019.Benzene -0.26 -0.24 -0.29 -0.57 0.18 0.01 0.23 0.08 0.04 ,653* 0.13 -0.13 -,685* -,63* -,70* -0.51 -0.33 -0.05 1.0020.Toluene 0.03 0.11 0.41 0.20 -0.18 -0.20 -0.42 -0.12 0.43 -0.19 -0.26 0.10 ,580* ,699* 0.57 0.49 0.26 -0.06 -,608* 1.0021.Ethylbenzene -0.35 -0.31 ,585* -0.01 -0.48 -0.45 -0.33 -0.22 0.00 -0.28 0.10 0.26 0.47 ,601* ,678* 0.46 -0.01 0.31 -0.57 ,643* 1.0022.m,p-Xylene -0.33 -0.37 0.27 -0.09 -,74** -0.30 0.15 0.08 0.01 -0.21 0.48 0.20 0.09 0.35 0.32 0.29 -0.06 ,629* -0.22 0.33 ,734** 1.0023.Styrene 0.09 0.25 -0.23 0.28 -0.28 0.33 0.54 0.49 0.20 -0.35 ,701* 0.44 0.22 0.14 -0.02 0.23 0.29 ,758** 0.04 -0.19 0.05 0.43 1.0024.TMB -0.28 -0.17 0.35 -0.01 -,73** -0.29 0.04 0.16 0.20 -0.29 0.38 0.15 0.24 ,601* 0.53 0.53 0.32 0.51 -0.34 0.55 ,776** ,860** 0.42 1.0025.Alfa-pinene 0.10 0.43 -0.34 0.33 0.05 0.48 0.22 ,643* 0.24 0.03 0.52 0.08 -0.07 0.19 0.10 0.13 0.24 0.36 0.16 -0.19 -0.15 0.17 ,591* 0.26 1.0026.Limonene 0.19 0.36 0.08 0.49 0.17 0.45 -0.16 0.37 -0.03 -0.06 0.40 0.23 0.20 0.33 0.42 0.40 0.23 0.24 -0.11 -0.21 0.01 -0.08 0.31 0.12 ,713** 1.0027.NO2 -0.26 -0.14 0.24 -0.12 0.54 -0.26 -0.28 -0.54 -0.01 0.38 -0.55 -0.15 0.03 0.32 0.17 0.17 -,592* -0.46 0.13 0.29 -0.03 -0.17 -0.49 -0.18 -0.09 -0.13

Bold values indicate ρ>0.6 *p<0.05, **P<0.01urban 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26 27

1.Formaldehyde 1.002.Acetaldehyde ,615* 1.003.ACR+ATN ,825** ,783** 1.004.Propanal ,594* ,832** ,769** 1.005.Benzaldehyde ,650* ,629* ,657* 0.56 1.006.Pentanal ,585* ,782** ,641* ,796** 0.45 1.007.p-Tolualdehyde 0.02 -0.44 -0.11 -0.57 -0.09 -0.29 1.008.Hexanal 0.50 ,825** ,678* ,790** ,769** ,768** -0.32 1.009.n-Pentane -0.26 0.24 -0.16 -0.15 -0.14 0.20 -0.02 0.07 1.0010.n-Hexane 0.10 -0.36 0.04 -0.06 0.01 -0.37 0.10 -0.41 -0.57 1.0011.n-Heptane -0.05 -0.09 0.23 -0.04 -0.06 -0.39 0.03 -0.09 -0.33 0.38 1.0012.n-Octane 0.17 -0.06 0.22 -0.05 0.10 -0.44 -0.01 -0.16 -,608* 0.50 ,769** 1.0013.n-Nonane 0.11 0.22 0.17 0.13 -0.17 0.00 -0.21 -0.24 0.36 0.33 0.22 0.09 1.0014.n-Decane 0.44 0.57 0.43 ,748** 0.16 0.54 -,692* 0.38 -0.05 0.04 -0.12 -0.10 0.36 1.0015.n-Undecane -0.03 0.20 -0.17 0.34 0.05 0.33 -0.50 0.14 -0.08 -0.10 -,699* -0.31 -0.16 0.39 1.0016.n-Dodecane 0.10 0.24 -0.01 0.36 0.21 0.54 -0.16 0.33 -0.06 -0.27 -,769** -0.49 -0.40 0.10 ,825** 1.0017.n-Tridecane 0.29 0.41 0.35 0.31 ,713** 0.31 -0.08 ,755** -0.11 -0.33 0.04 0.09 -,608* 0.01 -0.03 0.10 1.0018.Cyclohexane 0.04 -0.20 0.24 -0.08 -0.08 -0.38 0.15 -0.20 -0.22 0.50 ,825** 0.48 0.35 0.02 -,797** -,867** -0.11 1.0019.Benzene 0.15 ,594* 0.41 0.38 ,643* 0.30 -0.15 ,636* 0.40 -0.30 -0.14 -0.24 0.00 0.15 0.01 0.06 0.50 -0.03 1.0020.Toluene 0.55 0.36 ,706* 0.46 0.50 0.06 -0.22 0.24 -0.40 0.52 0.45 0.50 0.28 0.39 -0.25 -0.36 0.15 ,594* 0.34 1.0021.Ethylbenzene 0.52 0.17 0.50 -0.01 0.46 0.16 0.57 0.26 0.16 0.05 0.18 -0.02 0.07 -0.15 -,692* -0.41 0.32 0.45 0.34 0.36 1.0022.m,p-Xylene 0.37 0.18 0.38 -0.11 0.36 0.13 0.55 0.24 0.38 -0.20 0.11 -0.15 0.04 -0.24 -,713** -0.42 0.31 0.36 0.42 0.20 ,951** 1.0023.Styrene -0.09 0.04 -0.01 0.20 0.17 0.05 0.08 0.20 -0.07 0.27 -0.07 -0.12 -0.01 0.23 0.22 0.10 0.18 0.04 0.33 0.02 0.04 -0.09 1.0024.TMB 0.34 ,783** 0.52 ,608* 0.14 0.54 -0.55 0.43 0.37 -0.33 -0.08 -0.09 0.43 ,720** 0.22 0.01 0.05 -0.07 0.45 0.32 -0.04 0.02 0.04 1.0025.Alfa-pinene 0.52 0.51 0.57 0.43 ,769** 0.51 0.04 ,629* 0.21 -0.02 -0.26 -0.31 -0.04 0.23 -0.04 0.12 0.54 0.02 ,755** 0.45 ,657* ,601* 0.31 0.27 1.0026.Limonene -0.04 0.39 0.04 0.49 0.38 0.23 -0.52 ,587* 0.03 -0.31 -0.15 -0.20 -0.17 0.45 0.38 0.23 0.45 -0.20 0.51 0.00 -0.23 -0.21 0.46 0.25 0.22 1.0027.NO2 -0.57 -0.12 -0.41 -0.20 -0.46 0.04 -0.17 -0.02 0.52 -,727** -0.32 -,608* -0.30 -0.09 0.10 0.15 -0.03 -0.28 0.10 -0.52 -0.30 -0.04 -0.25 0.14 -0.17 0.15 1.00

industrial 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27.

1.Formaldehyde 1.00

2.Acetaldehyde 0.29 1.003.ACR+ATN ,608* 0.34 1.004.Propanal 0.45 ,73

4** 0.19 1.00

5.Benzaldehyde 0.48 0.42 ,678* 0.34 1.00

6.Pentanal ,685* 0.54 0.27 ,888** 0.29 1.00

7.p-Tolualdehyde -0.05 0.17 0.29 0.17 0.34 0.18 1.00

8.Hexanal ,657* ,629* 0.19 ,797** 0.36 ,88

8** 0.27 1.00

9.n-Pentane -0.20 0.23 -

0.46 0.29 0.03 0.21 0.03 0.35 1.00

10.n-Hexane -0.41 -0.46 -

0.41 -0.52 -,591* -0.51 -0.57 -,64

0* 0.04 1.00

11.n-Heptane -0.36 0.41 -

0.08 0.23 0.11 -0.05 -0.17 -0.11 ,587* 0.26 1.00

12.n-Octane 0.11 0.29 -0.05 0.38 0.03 0.37 -0.05 0.33 ,75

5** 0.13 ,636* 1.00

13.n-Nonane -0.15 0.04 -

0.38 0.26 -0.21 0.28 0.00 0.18 ,790** 0.28 0.55 ,85

3** 1.00

14.n-Decane -0.20 -0.24 -

0.54 -0.08 -0.17 -0.03 -0.21 0.07 ,839** 0.23 0.36 ,671* ,72

0** 1.00

15.n-Undecane 0.33 -0.08 -0.24 0.19 -0.08 0.38 -0.08 0.49 0.55 0.16 -

0.09 0.50 0.45 ,587* 1.00

16.n-Dodecane 0.44 -0.28 -0.08 0.00 -0.16 0.34 -0.24 0.35 0.31 0.16 -

0.22 0.42 0.33 0.56 ,853** 1.00

17.n-Tridecane 0.41 -0.20 -0.14 0.29 0.26 0.40 -0.28 0.38 0.36 -

0.11-

0.08 0.23 0.19 0.50 ,636* ,629* 1.00

18.Cyclohexane -0.06 0.38 0.08 0.00 0.36 -0.15 -0.10 -0.01 0.43 0.04 ,685* 0.45 0.34 0.30 -

0.17 -0.24 -0.15 1.00

19.Benzene -0.34 0.45 -

0.43 0.48 0.08 0.27 0.42 0.43 ,783**

-0.29 0.43 0.42 0.53 0.41 0.21 -0.16 0.04 0.24 1.00

20.Toluene 0.27 0.02 0.48 0.13 0.34 0.25 ,671* 0.16 -0.15

-0.15

-0.11 0.08 0.10 -

0.31 0.06 -0.04 -0.15 0.03 -0.04 1.00

21.Ethylbenzene 0.03 0.14 -0.31 0.57 -0.03 0.57 0.15 0.40 ,594* -

0.04 0.33 ,580* ,825** 0.42 0.29 0.13 0.31 0.14 0.57 0.22 1.00

22.m,p-Xylene -0.01 0.00 -

0.26 0.44 0.08 0.45 0.20 0.28 ,622* -0.04 0.36 ,608* ,83

2** 0.52 0.29 0.15 0.38 0.20 0.54 0.27 ,958** 1.00

23.Styrene 0.07 -0.08 -0.46 0.33 -0.33 0.45 -0.34 0.25 0.53 0.30 0.28 0.54 ,76

9** 0.55 0.45 0.46 0.46 0.07 0.24 -0.07

,805**

,725** 1.00

24.TMB 0.17 0.10 -0.34 0.42 -0.08 0.56 0.12 0.52 ,699* 0.10 0.20 ,643* ,83

2** 0.55 ,685* 0.49 0.39 0.13 0.52 0.29 ,846**

,790**

,798** 1.00

25.Alfa-pinene ,748** 0.29 0.28 ,657* 0.41 ,80

4** 0.13 ,720** 0.29 -

0.27 0.01 0.54 0.44 0.17 0.54 0.43 0.52 0.13 0.14 0.48 ,615* ,594* 0.48 ,685* 1.00

26.Limonene 0.52 -0.13 0.48 -0.10 0.48 -0.03 -0.48 -0.14 -0.27 0.09 0.06 0.01 -

0.20-

0.05-

0.08 0.13 0.38 0.34 -,629* 0.03 -0.19 -

0.08 0.00 -0.22 0.29 1.00

27.NO2 - 0.03 - 0.10 -0.34 -0.08 0.06 -0.05 ,72 0.13 ,587* ,657* ,74 ,685* 0.11 -0.02 - 0.36 ,650* - 0.52 0.56 0.40 0.39 - - 1.00

0.53 0.56 0** 1** 0.04 0.18 0.01 0.41