Estimates of sources of air pollution in Christchurch compared with recorded concentrations | The Meteorological Society of New Zealand

Estimates of sources of air pollution in Christchurch compared with recorded concentrations

P. Palmer

In the 1998 “Christchurch inventory of total emissions” the mass of air pollutants emitted into the air during the course of a ‘typical winter’s day’ from traffic, industry and home heating were estimated. These estimates have been used as the basis for deriving regulations to reduce the amounts of healthdamaging pollutants in the air we breathe. In this paper the estimates of the amounts of three of these pollutants, fine particles with an aerodynamic diameter less than 10 microns (PM10), carbon monoxide (CO), and oxides of nitrogen NO and NO2 (NOx), are compared with the concentrations recorded at the St Albans Air Quality Monitoring Station. Calculations using a model of the distribution of PM10 in the air and these inventory estimates gave good agreement between recorded and calculated concentrations. From this agreement it has been claimed that the model validates the inventory estimates. Using the same model and the estimates of emissions of NOx and CO from the inventory, the recorded concentrations of these were from four to six times higher than the calculated concentrations. The inventory estimated that almost equal amounts of PM10 and NOx were emitted during winter evenings. The concentration of NOx recorded in the air was regularly four to five times higher than the concentration of PM10. Similarly, the inventory estimated that ten times more CO than PM10 was emitted. However, the concentration of CO in the air was almost 60 times the concentration of PM10. These results call into question the claim that the model with its several assumptions validates the estimates of emissions contained in the inventory. It is asked whether these estimates are shown to be a sound basis for forming policies with very considerable health, social and economic consequences.

Back to top