LCI - Particular Matter Formation

Air pollution causing primary and secondary aerosols in the atmosphere can have a substantial negative impact on human health, ranging from respiratory symptoms to hospital admissions and death. Inhalation of different particulate sizes can cause various health problems. The effects of chronic PM exposure on mortality (life expectancy) are most likely attributable to PM2.5 rather than to coarser particles.

Cause-effect pathway

The impact model is addressing emissions of PM2.5, as well as precursor emissions sulfur dioxide (SO₂), nitrogen oxides (NO_x), ammonia (NH₃) and consequent effects on the Area of protection ‘Human Health’.

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.
Level of robustness: evidence for effects from primary PM is available and therefore considered robust. There is evidence concerning human health risks at ambient concentrations of secondary PM from SO₂, NO_x and NH₃ available, but the level of effect is still under debate There are more studies indicating health effects from secondary PM from SO₂ than from NO_x or NH_3.

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 particulate matter formation caused by emitted substance x in world region i (CF_x,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 (dM_x,i in kg·yr^-1). This CF for human health damage is composed of a dimensionless intake fraction (iF_{x, i→j}), providing the population intake of PM2.5 in receptor region j (in kg/yr) following an emission change of substance xin source region i (in kg/yr), an effect factor (>EF_e), describing the cases of health effect e per kg of inhaled PM2.5, and a damage factor (DF_e), which describes the years of life lost per case of health effect e. In equation this reads:

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