LCA Methodology Human Health Damages due to Indoor Sources of Organic Compounds and Radioactivity in Life Cycle Impact Assessment of Dwellings Part 1: Characterisation Factors

Goal, Scope and Background. Methodologies based on life cycle assessment have been developed to calculate the environmental impact of dwellings. Human health damage due to exposure to substances emitted to indoor air are not included in these methodologies. In order to compare this damage with human health damages associated with the rest of the life cycle of the dwelling, a methodology has been developed to calculate damages to human health caused by pollutants emitted from building materials. Methods. Fate, exposure and health effects are addressed in the calculation procedure. The methodology is suitable for organic substances, radon and elements emitting gamma radiation. The (Dutch reference) dwelling used in the calculation was divided in three compartments: crawl space, first floor and second floor. Fate factors have been calculated based on indoor and outdoor intake fractions, dose conversion factors or extrapolation from measurements. Effect factors have been calculated based on unit risk factors, (extrapolated) effect doses or linear relationship between dose and cancer cases. Damage factors are based on disability adjusted life years (DALYs). Results and Discussion. Characterisation factors have been calculated for 36 organic compounds, radon and gamma radiation emitted by building materials applied in a Dutch reference dwelling. For organic compounds and radon, the characterisation factors of emissions to the second floor are 10–20% higher than the characterisation factors of emissions to the first floor. For the first and second floor, the characterisation factors are dominated by damage to human health as a result of indoor exposure. The relative contribution of carcinogenic and non-carcinogenic effects to the characterisation factors is generally within one order of magnitude, and up to three orders of magnitude for formaldehyde. Introduction In life cycle impact assessment (LCIA), several methods have been developed to calculate the impact of emissions of harmful components on human health [1–7]. These methods take into account outdoor sources of contamination. A method to evaluate the impact of indoor sources on human health due to indoor exposure is, however, still missing [8,9]. The reason for this absence is that LCIAs usually do not take into account local effects of products on users [8]. However, environmental comparisons and improvements for building products may be biased by excluding the impact of indoor air pollution. For instance, human health damage scores of concrete compared to wood may be underestimated by excluding indoor air emissions of radon and gamma radiation. Another example is that the positive influence on human health of mechanical indoor air ventilation in buildings is not accounted for by disregarding impacts of indoor air pollution. Indoor Pollutants, Part 1 LCA Methodology 310 Int J LCA 10 (5) 2005 The impact of indoor pollution on human health may be an important factor for the LCIA of dwellings, because people live in houses for a great part of their lives. The Dutch Health Council for instance estimated the number of casualties due to lung cancer as a result of exposure to radon in the Netherlands at 800 per year [10]. In a review of radiation exposure in the Netherlands, it appears that nearly 50% of the total average annual dose per capita of the Dutch population originates from radon or gamma radiation from building materials [11]. Apparently, the exclusion of indoor exposure to radioactive elements originating from building materials leads to an underestimation of the human health risks in the life cycle assessment of dwellings. Something similar may hold for organic pollutants. For instance, Sexton et al. showed an increased indoor concentration of fifteen organic compounds in three urban communities, if compared with outdoor concentrations [12]. This article presents characterisation factors for 36 organic compounds, radon and gamma-radiating elements present in building materials. The characterisation factors are calculated for a Dutch reference dwelling [13,14]. It is assumed that this dwelling in occupied by three persons. Fate, effects and damages are incorporated in the characterisation factor calculations [7]. Fate factors of organic compounds and radon are calculated using an indoor airflow and exposure model for dwellings. Exposure in both indoor and outdoor environment is considered. Effect factors are calculated using unit risk factors for carcinogenic effects [7], no observed effect levels (NOELs) and lowest observed effect levels (LOELs) for non-carcinogenic effects [15], and epidemiological data for ionising radiation [1]. Damages to human health are expressed in disability adjusted life years (DALYs) [1,4,7]. The impact categories that are taken into account in this research are given in Table 1. Carcinogenic effects, non-carcinogenic effects and effect of ionising radiation are relevant for exposure in both indoor and outdoor environment. Respiratory effects caused by ozone creation, effects of climate change and effects of ozone layer depletion are only relevant for exposure in outdoor environment. Parameter values used in this methodology are given in Appendix 2 (online edition only ).