Good air quality is essential for human health and the environment. Motor vehicle emissions, home heating, industrial emissions, outdoor burning, pollen and dust are all contributors to reduced air quality.
Many contaminants are produced from these sources including particles and gases. In many New Zealand towns and cities, PM10 (particles in the air with a diameter less than 10 micrometres) is the main concern. The main source of particles in Greater Christchurch is from burning wood and coal in winter. In the past, Christchurch experienced very high daily PM10 averages compared to other cities. PM10 are linked to poor public health outcomes, including respiratory disease.
Key points
Monitoring in Christchurch, Rangiora and Kaiapoi in 2018 showed that the Christchurch airshed had the most air pollution with four PM10 exceedance days. Within Christchurch, there are three sites where PM10 was measured. In the St Albans residential area, there were three exceedance days while in Woolston, an industrial area, four were measured. Another roadside site in Riccarton Road had one high PM10 day. Rangiora and Kaiapoi both improved from the previous year, with Kaiapoi dropping from ten days in 2017 to two in 2018, and Rangiora from six days to zero.
Note this is an interactive chart and you can select the legend items to change what is shown on the graph.
Commentary
There has been an improvement in air quality in greater Christchurch since 2000, with the number of PM10 exceedance days dropping markedly over the period from between 50-60 exceedance days measured at the St Albans site in the early 2000s, to 4 in 2017.
The number of PM10 exceedances each year in Rangiora has ranged from 3 to 13, driven mainly by weather. Kaiapoi’s air quality has also improved since the early 2000s. There were 48 exceedance days in 2001, when monitoring started, to 10 in 2017.
A further reduction in PM10 concentrations is still needed to meet the National Environmental Standards for Air Quality (NESAQ) target of only one exceedance. This target should already be met in Rangiora, while Christchurch and Kaiapoi have a couple more years to meet it by September 2020. The current target for Christchurch and Kaiapoi is no more than three exceedances.
See the Environmental Indicator on Greenhouse Emissions for data on transport emissions in Greater Christchurch.
Data notes
The Government set national environmental standards for air quality in 2004 and updated these in 2011. These standards are currently under review. The legislation that sets these standards is called the Resource Management (National Environmental Standards for Air Quality) Regulations 2004 – commonly referred to as the NESAQ. The standards include five main air contaminants that, when breathed in, can cause negative effects to people’s health:
Particulate Matter (PM10) Includes fine particles (less than 2.5 micrometers) and coarse particles (between 2.5 and 10 micrometers)
sulphur dioxide (SO2)
carbon monoxide (CO)
nitrogen dioxide (NO2)
ozone (O3).
Canterbury has eight gazetted airsheds (management areas) that have exceeded the national environmental standard. Three of these airsheds are in the Greater Christchurch area - Christchurch (with monitoring sites in St Albans,Woolston and Riccarton Road), Kaiapoi, and Rangiora. These areas have targets for compliance with the NESAQ from 1 September 2016 and 2020.
