Details of Westbury Plume Plotter

This page should be read in conjunction with How Plume Plotter Works. It provides more details specific to the Westbury version of Plume Plotter.

Stacks and buildings

Building measurements are taken from [1].

The image below shows the layout of the stack and building modelled. North is at the top; colours and numbers indicate the height of the buildings and the stack:

Stack measurements

These are taken from [1]:

The following values are used for albedo, Bowen ratio and roughness length. Roughness length is as specified in [1]:


The emission rates of pollutants are taken from [1]:

PollutantEmission rate
per second
Oxides of nitrogen6.161 g
Sulphur dioxide1.54 g
Carbon monoxide2.567 g
Particulates257 mg
Hydrogen chloride308 mg
TOC513 mg
Hydrogen flouride51 mg
Ammonia513 mg
Cadmium and Thallium1.027 mg
Mercury1.027 mg
Other metals15.4 mg
Dioxins and furans3.08 ng
PAHs5.39 μg
PCBs257 μg

Background levels

The background levels of pollutants are taken from [2]:

concentration per m3
Oxides of nitrogen13.19 μg
Sulphur dioxide2.21 μg
Carbon monoxide266 μg
Particulates14.91 μg
Hydrogen chloride710 ng
TOC390 ng
Hydrogen flouride2.35 μg
Ammonia2.93 μg
Cadmium and Thallium570 pg
Mercury2.8 ng
Other metals141.7 ng
Dioxins and furans32.99 fg
PAHs980 pg
PCBs128.9 pg

Weather data

Weather data is taken from METAR reports from a local airport: Bristol.

Upper air data is the latest reported by the Herstmonceux upper air station.


1. Northacre Facility Environmental Statement: Appendix 8.3 - Emissions Modelling. Fichtner. July 2020.

2. Northacre Facility Environmental Statement: Appendix 8.3 - Baseline Analysis. Fichtner. July 2020.