Indoor and outdoor airborne pollutants levels on the ... · Materials and Methods – Study design 6 Indoor and outdoor airborne pollutants levels on the street- and back-side of

Indoor and outdoor airborne pollutants levels on the street- and back-side of a building in a trafficked

urban area

European Aerosol Conference 2015 - Milan (Italy), September 6-11, 2015

S. Rovelli(1), S. Zauli Sajani(2), A. Cattaneo(1), I. Ricciardelli(3), A. Trentini(3), D. Bacco(3), V. Poluzzi(3), P. Lauriola(2) and D.M. Cavallo(1)

(1) Department of Science and High Technology, University of Insubria, via Valleggio 11, 22100 Como, Italy (2) Regional Centre for Environment and Health, ARPA Emilia-Romagna, via Begarelli 13, 41121 Modena, Italy

(3) Regional Centre for Urban Areas, ARPA Emilia-Romagna, via Rocchi 19, 40138 Bologna, Italy

Introduction 2

Indoor and outdoor airborne pollutants levels on the street- and back-side of a building in a trafficked urban area European Aerosol Conference, 2015 – Milan (Italy), September 6-11, 2015

General Project:

• «SUPERSITO» Project: improve the knowledge regarding the environmental and health aspects of fine and ultrafine particles, both indoors and outdoors (http://www.arpa.emr.it/supersito)

• 7 Work Packages («Linee Progettuali» - LP) to develop and realize an accurate survey on the atmospheric pollution in the Emilia-Romagna Region, through the monitoring of physical, chemical and toxicological parameters that will be then used as a valid support in epidemilogical and environmental studies

• LP5: «Human exposure to Particulate Matter (PM) in indoor environments» • Characterize the human exposure to airborne pollutants of outdoor origin

in indoor environments, with a particular focus on PM mass and chemical composition

http://www.arpa.emr.it/supersito










Aims – LP5 3

General aim «LP5» Focus on the variability of human exposure to air pollution in urban areas, with particular regards to the traffic source, that is considered the main source of fine and ultrafine particles in urban environments not directly infleunced by industrial emissions. Data used to assess:

a) Human health risk associated with a different proximity to traffic sources b) Differences in human health risk due to PM exposure during the summer period and

the winter season Study 1. Assessment of I/O ratios and spatial variability of traffic-related air pollutants simultaneously measured at a traffic site and a residential site, located in a low traffic area (Zauli Sajani et al., 2015)

Study 2. Assessment of concentration trends between two locations of the same building, that are at the front-side and at the back-side of the bulding itself

Study 3. Assessment of spatial variability along the vertical profile


Aims – Study 2 4

• Detrimental effects on human health due to the exposure to PM and other traffic-related air pollutants

• Limited epidemiological evidences of adverse health outcomes associated with a different proximity to traffic sources

• Most of the time spent indoors

Need of an accurate assessment of indoor exposures to the outdoor air pollution Development of an experimental approach to:

Characterize the indoor and outdoor concentrations of PM2.5 (mass and chemical composition), UFPs (number concentration and size distribution) and gaseous pollutants (CO and NO2)

Investigate the street-side/back-side trends and differences of those pollutants


• Environmental monitoring of PM2.5, UFPs, CO and NO2 at two sites with different

characteristics in relation to the traffic source (street- and back-side of a two-storey building) – urban area of Bologna, Northern Italy

• Indoor sites selected on the basis of the following characteristics:

uninhabited and with no indoor sources similar in terms of volumes and building materials at the same height from the street level with a comparable Air Exchange Rate (AER)

• Two monitoring campaigns conducted at the two locations – summer (11th – 25th June

2013) and winter session (28th November 2013 – 13th December 2013)

• Indoor and outdoor sampling performed simultaneously on the street- and back-side of the study building

Street-side

Materials and Methods – Study design 5

Street-side

Back-side

Back-side


Materials and Methods – Study design 6


• Measurements based on the tracer gas-decay technique, using CO2 as tracer gas, to verify the estimated AERs (ASTM Standard E741-95 Method)

• AERs controlled by installing in each room a mechanical system, set at a specific value

in order to obtain an estimated AER of about 0.4 h-1

Materials and Methods – Sampling Methods 7


PM2.5: 24-h PM2.5 concentrations collected via Skypost (flow rate of 2.3 m3h-1) • Gravimetric mass determination (UNI EN 12341) • Chemical analysis for:

- Organic (OC) and Elemental Carbon (EC) – Thermal Optical Trasmittance (TOT) - Metals (As, Cd, Fe, La, Pb, Sb, Sn, Mn, V, Zn) – ICP-MS - Ions (NH4

+, NO3-, SO4

2-, K+) – Ion chromatography (IC)

UFPs: continuous measurements by means of FMPS NO2: collection by radial symmetry diffusive samplers (Radiello®)

• Summer: 15 days of exposure time • Winter: two one-week samplings

CO: continuous measurements by means of Langan T15v electrochemical analyzers

• Zeroing and calibrating procedure performed before and after the monitoring campaign in a glove bag using two certified standard CO gas mixtures (< 50 ppb and 10.3 ppm)

• Correction for temperature on the basis of specific experimental quadratic equations, because of the known interference of temperature on the instrumental baseline

• Sampling limited to the cold season, due to the excessive interference on the output signal when temperatures are elevated (> 28/30 °C)

Results – PM2.5 Mass and Chemical Composition 8

Front-side Back-side

Outdoor Indoor

I/O

Outdoor Indoor

I/O n

Mean n

Mean n

Mean n

Mean

(min - max) (min - max) (min - max) (min - max)

24-h PM2.5 (µg/m3)

Summer 11 15.6 11 15.5 0.99 11 11.1 11 8.5 0.77

(11.3 – 23.8) (11.5 – 20.1) (7.5 – 16.5) (3.8 – 12.8)

Winter 15 47.1 14 26.5 0.56 15 43.4 15 20.2 0.47

(27.0 – 68.1) (16.4 – 41.1) (23.9 – 63.7) (9.5 – 35.7)

Total 26 31.3 25 21.7 0.69 26 27.3 26 14.4 0.53

(11.3 – 68.1) (11.5 – 41.4) (7.5 – 63.7) (3.8 – 35.7)

• PM2.5 outdoor winter levels more than three times higher, on average, compared to the summer data

• Small but significant differences (p < 0.001) in PM2.5 outdoor concentrations between front- and back-side (Ofront/Oback = 1.13)

• Indoor gradients more pronounced (Ifront/Iback = 1.50) • I/O ratios < 1, lower at the back-side and during the cold season


0,0

7,0

14,0

21,0

28,0

35,0

V As Cd Sn Sb Pb Zn Mn La

0,003% 0,002% 0,001% 0,01% 0,004% 0,023% 0,12% 0,023% 0,00%

0,006% 0,002% 0,001% 0,018% 0,007% 0,024% 0,13% 0,026% 0,00%

0,004% 0,002% 0,001% 0,009% 0,006% 0,026% 0,13% 0,020% 0,00%

0,006% 0,003% 0,001% 0,009% 0,004% 0,036% 0,17% 0,026% 0,00%

Out front Ind front Out back Ind back

0,0

1,5

3,0

4,5

6,0

7,5

9,0

OC EC NH4+ NO3- SO42- K+ Fe

28,2% 12,7% 9,3% 26,2% 10,6% 1,4% 0,7%

31,4% 19,8% 4,1% 5,9% 9,8% 1,7% 1,2%

28,7%

8,2% 10,4% 28,4% 11,7% 1,6% 0,4%

41,5%

11,8%

5,3% 7,1%

14,7% 2,4% 0,5%

Out front Ind front Out back Ind back

Results – PM2.5 Mass and Chemical Composition 9

• OC and NO3- as the largest

contributors to the outdoor PM2.5 mass, followed by EC, SO4

2- and NH4+

• Primary role of OC also indoors, with a pronounced decrease of NO3

- (I/Ofront = 0.16; I/Oback = 0.13) and NH4

+ (I/Ofront = 0.30; I/Oback = 0.27)

• Metals: minor component (< 0.3%) – primary role played by Fe and Zn

Mean contributions of the chemical species to the average indoor and outdoor PM2.5 levels, at both indoor and outdoor sites. Concentrations are expressed in µg/m3 (Figure a) and ng/m3 (Figure b)

(a)

(b)


Results - PM2.5 Mass and Chemical Composition 10

Outdoor Indoor

Front/Back p-value Front/Back p-value

Elemental Carbon (EC) 1.76 < 0.001 2.53 < 0.001

Iron (Fe) 1.73 0.122 3.66 0.001

Manganese (Mn) 1.31 0.003 1.5 0.002

Tin (Sn) 1.30 0.246 3.02 < 0.001

Total Carbon (TC) 1.2 0.016 1.45 < 0.001

Organic Carbon (OC) 1.13 0.038 1.14 0.008

Zinc (Zn) 1.11 0.053 1.20 0.008

Nitrates (NO3-) 1.06 0.073 1.25 0.086

Sulphates (SO42-) 1.04 0.184 1.01 0.889

Ammonium (NH4+) 1.02 0.456 1.14 0.129

Vanadium (V) 1.01 0.741 1.35 0.002

Lanthanum (La) 1.00 0.486 1.20 0.138

Arsenic (As) 1.00 0.966 1.07 0.171

Cadmium (Cd) 1.00 0.802 1.07 0.866

Lead (Pb) 0.99 0.782 1.01 0.686

Potassium (K+) 0.98 0.012 1.03 0.279

Antimony (Sb) 0.88 0.591 2.25 0.002

• Significant differences between outdoor front- and back- average levels for EC and Mn

• Large, but not statistically significant, the outdoor trends for Fe and Sn

• Same patterns confirmed indoors, with indoor differences higher than outdoor

• Largest Ifront/Iback ratios for Fe and Sn, with values more than three times higher at the street- compared to the back-site

• EC: important component of diesel exhaust

particulate • Mn and Sn: typical markers of vehicle

emissions for PM2.5 • Tyre wear, vehicle component detachment,

fluid leakage: known sources of elements (e.g. Cu, Mn, Fe)

• Traffic-induced road dust resuspension: secondary contributor to fine-sized aerosol


Results - UFPs Number Concentration and Size Distribution 11

Front-side Back-side

Outdoor Indoor

I/O

Outdoor Indoor

I/O n

Mean n

Mean n

Mean n

Mean

(min - max) (min - max) (min - max) (min - max)

1-h UFPs (pt/cm3)

Summer 353 15502 353 5109 0.33 353 6169 353 2932 0.48

(2118 - 38367) (1472 - 10773) (647 - 24308) (213 - 7901)

Winter 299 36994 299 10595 0.29 299 8948 299 4266 0.48

(3095 - 120931) (2854 - 21142) (1781 - 26860) (1730 - 8854)

Total 652 25358 652 7625 0.30 652 7444 652 3544 0.48

(2118 - 120931) (1472 - 21142) (647 - 26860) (213 - 8854)

• Large and significant differences for the UFPs number concentration, both indoors (Ifront/Iback = 2.2; p < 0.001) and outdoors (Ofront/Oback = 3.4; p < 0.001)

• Higher differences during the cold season

• I/O UFPs ratios < 1 and lower than I/O PM2.5 ratios (electrostatic deposition)


Results - UFPs Number Concentration and Size Distribution 12

• Multimodal distribution at the outdoor front-side • Sharp peaks – higher during the cold season – at about

20 and 30-40 nm - Particles directly emitted by vehicles - Freshly nucleated particles formed when the hot

exhaust gases expelled from the tailpipe of a vehicle are diluted with ambient air

• Less pronounced peak in the 30-40 nm size range at the outdoor back-side

• Plateau in the indoor distributions - Aitken mode (40-50 nm) - Accumulation mode (100-150 nm)


Results – Gaseous pollutants 13

Front-side Back-side Outdoor Indoor

I/O

Outdoor Indoor

I/O n

Mean n

Mean n

Mean n

Mean (min - max) (min - max) (min - max) (min - max)

1-h CO (ppm)

Winter 452 1.28 452 1.11 0.87 124 0.51 117 0.24 0.47

(0.25 – 2.85) (0.34 – 2.37) (0.21 – 1.29) (0.01 – 0.55)

NO2 (µg/m3)

Summer 1 61.8 2 47.6* 0.77 Data missing 2 38.0*

Winter 4 97.0** 4 50.8** 0.52 4 77.2** 4 48.9** 0.63

Total 5 78.9 6 49.6 0.63 4 77.2 6 43.5 0.56 *Concentration value obtained as mean value of diffusive samplers exposed in duplicate for 15 days **Concentration value obtained as mean value of duplicates exposed during two one-week samplings Precision, expressed as coefficient of variability (CV%) from duplicate measurements, was always good (3.0 – 10.6 %)

CO • I/O ratios < 1 (absence of indoor CO sources) • Marked differences between front- and back-

side (Ifront/Iback = 4.6; Ofront/Oback = 2.5) • Strong and significant correlation (r = 0.93; p <

0.05) between both hourly and daily concentrations of CO and UFPs at the front-side

NO2

• NO2 winter levels higher than those monitored during summer

• I/O ratios < 1 • Slight gradient in relation to the proximity to

the traffic source


Conclusions 14

• Study focused on the assessment of differences and trends between the two opposite sides of a building for typical traffic-related air pollutants

• Marked and significant differences for UFPs, CO and elements as EC, Mn, Sn, Fe in relation to the proximity to the traffic source

• Significant, but less relevant, the spatial gradients for PM2.5 and NO2

• Important differences also in the shape of the outdoor particle size distribution

• Indoor levels much lower than outdoors, especially for UFPs, CO, nitrates, ammonium and indoor trends quite similar to those found outdoors

- Potentially high and not negligeable variability in the human exposure to outdoor airborne pollutants also for people living in the same building, due to a different

proximity to traffic sources

- Valid support in epidemiological studies Indoor and outdoor airborne pollutants levels on the street- and back-side of a building in a trafficked urban area

European Aerosol Conference, 2015 – Milan (Italy), September 6-11, 2015

15


Sabrina Rovelli, Ph.D. Student Department of Science and High Technology University of Insubria Via Valleggio 11, 22100 Como - Italy [email protected]

Thanks for your attention

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Indoor and outdoor airborne pollutants levels on the ... · Materials and Methods – Study design 6 Indoor and outdoor airborne pollutants levels on the street- and back-side of