Exposure of Finnish subpopulations to fine particles due domestic wood combustion

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• Abstracts should not exceed 300 words (2,000 characters).
• Abstracts reporting on research or investigations must include results. Statements such as “findings will be reported” are not sufficient.
• Abstracts must be submitted electronically at www.ises09.org by May 1, 2009.

Introduction

This abstract is exploring the method and results of GIS (Geographical Information System) based exposure assessment of Finnish population. Exposure is evaluated for fine particles of domestic wood combustion emissions in Finland. Concentration of PM2.5 (fine particles with aerodynamic diameter ≤ 2.5 µm) is used in intake fraction (iF) based exposure evaluation. In previous studies GIS has been used in evaluation of PM2.5 dispersion and assessment of exposure for PM2.5. Also mortality and hospital admissions as health effects of fine particles have been found in short-term studies. Previous studies have concluded that Finnish population average exposure for primary fine particle emissions is 0.54 µg/m3. Intake fraction for Finnish population has evaluated to be 3.31 per million for fine particles due to domestic wood combustion emissions. In this assessment four different education and age groups in Finland are taken account to intake fraction and exposure evaluations for fine particles of domestic wood combustion. Differences between men and women exposure to fine particles are also studied.

Material and Methods

The population data for Finland was obtained from the Statistics Finland Grid Database [1]. The dataset contained population numbers for Finland on a resolution of 250 x 250 m2 for 2004 of different age groups and 2005 of different education groups, respectively. PM2.5 emissions of domestic wood combustion in residential buildings were calculated with the Finnish Regional Emission Scenario (FRES) model. The dispersion model applied in this study was the urban dispersion modelling system. It includes a multiple source Gaussian plume model and a meteorological pre-processor MPP-FMI. Data of PM2.5 contained concentrations (ng/m3) with 1 km grid resolution. Data of dispersed concentrations were joined into population data with ArcGIS. using nearest concentration points of each population grid. Product of population and concentration of each grid and sum of this product over Finland was calculated with ArcGIS (eq. 1). Rest of iF calculation and exposure were implemented using Analytica ™ version 4.1 (eq. 2).

Intake fraction illustrates the fraction of pollution that is taken in via inhalation, ingestion and dermal by exposure for individual or population. In this study iF has been defined as fraction of fine particles of domestic wood combustion in residential buildings in Finland to Finnish population as following equation:

eq. 1 				iF = Σi(Ci * Popi) * Br / Q, 

where Pop is the number of population in grid cell i (persons), i = 1,2, ..., n, n is the total number of grid cells in the study area, C is the concentration increase of PM2.5 in the grid cell i due to a specified emission source category or area of emissions (g/m3), Br is the breathing rate (m3/s/person), and Q is the emission rate (g/s). A nominal breathing rate of 20 m3/day/person (~0.0002 m3/s/person) was adopted in this study as in many previous ones.

eq. 2 				C = (E x iF) / (Pop x Br) 

, where C is population average primary fine particle concentration (unit g/m3), iF is intake fraction, Pop is number of people, and Br is breathing rate. Constant 20 dm3/day breathing rate was used in the analyses.

Results

Intake fraction

The intake fraction didn’t vary a lot between men and woman (Table 1). Children had highest intake fraction and juvenile lowest. There were more variation between iF of educational subpopulation groups. People who had vocational education had highest iF and upper secondary school passed population had lowest.

Table 1. The intake fraction of fine particles of domestic wood combustion in residential buildings to female and males and different age and educational groups of Finnish population.

	iF (per million)
Female	1.7
Male	1.6
Children (0-17)	0.7
Juvenile (18-24)	0.3
Middle age (45–54)	0.5
Pensioner (65–)	0.5
Higher education	0.4
Vocational education	1.1
Upper secondary school	0.2
Comprehensive school	0.8

Exposure

Exposure for fine particles due to wood combustion in household buildings of Finland population varied between educational groups (Fig 1). Upper secondary school and higher education groups had higher exposure level (0.58 and 0.60 µg/m3) than comprehensive school and vocational education groups (0.50 and 0.54 µg/m3). In age groups juveniles exposed most (0.59 µg/m3) and pensioner least (0.50 µg/m3) to fine particles of domestic wood combustion. Children and middle age groups exposed to fine particles as 0.55 and 0.54 µg/m3. As the same as in iF estimation exposure was higher for females than for males (0.55 and 0.54 µg/m3).

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Figure 1. Exposure (µg/m3) of different population groups in Finland for fine particles of domestic wood combustion emissions.

Conclusions

Both iF and exposure varied between different subpopulations. Most differences of iF were in educational population groups. Exposure variations in educational and age groups can be caused