Report: TR02/20

Author: Emily Wilton (Environet)

Abstract

Air quality monitoring in Hamilton identifies suspended particulate (PM10) as the main contaminant of concern. Concentrations of PM10 in Hamilton are generally low, with up to 3 per cent of the annual concentrations typically within the MfE "alert" category indicating concentrations above 66 per cent of the guideline value. In 2001, two guideline exceedences were recorded giving a 99.7 percentile concentration of 52 µg m-3.

Sources of PM10 and other contaminants in Hamilton were assessed in 1997 using emission inventory methodology. This involves the assessment of contaminant discharge rates from a number of sources and quantifies them for a selected time period and area. The 1997 emission inventory was carried out in two phases: the assessment of emissions from domestic heating and motor vehicles and the assessment of emissions from industry. Results from these phases were not combined to give an overall assessment for Hamilton.

A further domestic heating emission inventory was carried out in 2001. The purpose of this assessment was to monitor changes in emissions since 1997 and to implement a number of methodological improvements. Similarly in 2002, an investigation into vehicle usage on the Hamilton road network was commissioned to provide estimates based on road network use in 2001 and projected use for 2021. The latter study is presented in detail in this report along with the estimated relative contribution of different sources in 1997 and 2001. Industrial emissions estimates for the latter are based on the 1997 study, as no update has occurred.

Collation of the 1997 emission inventory shows that 89 per cent of the PM10 emissions in Hamilton occur as a result of solid fuel burning for domestic home heating. About 10 per cent come from motor vehicle emissions and around 1 per cent from industry. Domestic heating and motor vehicles were each found to contribute about half of the carbon monoxide, sulphur dioxide and volatile organic compounds and motor vehicles were responsible for the majority of the nitrogen dioxide emissions (95 per cent). The industrial contribution to other contaminants was negligible (less than 1 per cent).

Vehicle registration data for Hamilton in 2001 indicates that around 87 per cent of vehicles registered use petrol, 13 per cent diesel and less than 1 per cent use other fuels such as LPG or CNG. Around 85 per cent of the registered vehicles are passenger cars. In 2001, around 2.5 million vehicle kilometres travelled (VKT) per day were estimated by Gabides Porter for Hamilton. Of these, about 26,000 occurred under the congested conditions that give rise to higher emission rates. Estimates for 2021 indicate an increase in VKT to just over 3 million per day. Despite this, a significant reduction in emissions of PM10, CO and VOCs is expected as a result of improved vehicle technology and fuel specifications.

Collation of the 2001 emission inventory data for home heating and motor vehicles indicates that domestic heating produces the majority (90%) of the PM10 in Hamilton. The remainder is attributed to motor vehicles (9 per cent) and industry (1 per cent).

Hamilton Emission Inventory Assessment : 1997 and 2001 [PDF, 198 KB]