a spatially differentiated life cycle impact assessment method

# Photochemical Ozone Formation

#### Human Health

###### Photochemical Ozone Formation

Air pollution causing tropospheric ozone in the atmosphere can have a negative impact on human health, e.g. respiratory problems, and terrestrial ecosystems, e.g. plant biomass decrease.

#### Cause-effect pathway

The impact model is addressing emissions of nitrogen oxides (NOx), and non-methane volatile organic compounds (NMVOC) and consequent effects on the Areas of protection ‘Human Health’ and ‘Terrestrial ecosystems’. This overview will focus on the human health effects only.

#### Modeling approach

A marginal approach for calculating the characterization factors is followed, meaning that the additional impact of a marginal increase in ozone precursor emission using today’s situation as the reference state was determined. Model results were determined following a change in anthropogenic emissions and is determined by lowering the year 2000 emissions by 20% for each of the 56 source regions. Impact is measured in disability adjusted life years for human health (DALYs) for human health.

#### Value choices

Time Horizon: not of importance as only short-living substances are involved.

#### Spatial variability

The method was applied to 56 world regions. Country-average CFs were determined from these region-specific factors. A global average is not considered meaningful but provided for background processes.

#### Characterisation factors

The endpoint characterisation factors (CFs for human health damage due to ozone formation caused by emitted precursor substance x in world region i (CFx,i in DALY·kg-1) are defined as the yearly change in Disability Adjusted Life Years (DALY) of all inhabitants (dDALY in yr·yr-1) due to a change in emission of substance x in source region i (dMx,i in kg·yr-1). This CF for human health damage is composed of a dimensionless intake fraction (iFx, i→j), providing the population intake of ozone in receptor region j (in kg/yr) following an emission change of substance x in source region i (in kg/yr), an effect factor (EFe), describing the cases of health effect e per kg of inhaled ozone, and a damage factor (DFe), which describes the years of life lost per case of health effect e. In equation this reads:

$$\mathsf{CF_{x,i}=\sum_j{\Biggl(\left(iF_{x,i\to j}\right)\cdot\sum_e\left(EF_{e,j}\cdot DF_{e,j}\right)\Biggr)}}$$