PM2.5 concentration from bus traffic in Helsinki in 2020

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Scope

• Spatial limits: Helsinki metropolitan area
• Temporal limits: year 2020
• Type of pollutant: primary PM2.5
• Source of pollutant: bus traffic

Definition

Causality

List of parents:

• Variable:PM2.5 emissions from bus traffic

Data

List of data files or sources:

• Database from EXPOLIS study (1996-1997) - individual measurements of total outdoor PM exposure
• Database from ULTRA study - fixed monitoring sites

Formula

Total PM2.5 exposure/concentration was used as the starting point for the calculations of PM2.5 due to bus traffic, subtracting the contributions from other sources.

E_bus = (E_c-E_lrt)/f_tr*f_bus

fi = (Em_i * wf_i)/Sum(Em_i*wf_i)

Where:

E_bus is average PM2.5 exposure to primary particles from local buses (μg/m³)
E_c is total exposure to combustion originating particles (μg/m³)
E_lrt is the concentration of combustion-based long-range transport (average exposure to long-range transported PM2.5)(μg/m³)
f_tr is the ratio of local road traffic exposure to local CoPM (no units)
f_bus is the ratio of local bus-derived primary CoPM to all local road-traffic-derived CoPM (no units)
Em_i is the CoPM emissions in the Helsinki area (%)
wf_i is the relative weight factors to CoPM-emissions (no units)
wf is an estimate of the the impact of a unit emission on the average population exposure in the area (no units)
Index i denotes different CoPM sources in Helsinki

Unit

μg/m³

Result

For accessible numerical results, go to Media:Gasbus model 01.ANA