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9 Nelson, Tasman and Marlborough Districts
Historically, air quality monitoring in Nelson and Tasman was based on measurements of black smoke (BS) and dates back to around 1983. The monitoring programme was initially set up by the then Department of Health, which was in part responsible for air quality. Monitoring was carried out at three locations in Nelson: the inner city, Vanguard Street and Quarantine Road during the months May to August inclusive from 1983, and at one location in Richmond (Tasman).
The 98th percentile smoke concentrations (seventh highest reading) in Nelson per year were typically within 50-120 µgm-3 for the Vanguard Street site, between 40 and 80 µgm-3 for the Quarantine Road site and less than 60 µgm-3 for the inner city site.
The first PM10 monitoring programme for Nelson commenced in May 2000 using a high volume gravimetric sampler which was situated at the Nelson fire station. A similar sampler was located in Tasman in the urban area of Richmond. Further PM10 monitoring was carried out in Nelson in 2001 using a gravimetric partisol sampler located at a monitoring site at Swift Suzuki.
The air quality monitoring programme in Marlborough, which included PM10 monitoring, commenced during 2000. This initially involved monitoring using a gravimetric high-volume sampler in Picton and Blenheim.
9.1 Monitoring sites and methods
Details of the seven ambient air quality PM10 monitoring sites within the Nelson, Tasman and Marlborough Districts are shown in Table 9.1. These are all residential neighbourhood monitoring sites and use predominantly gravimetric high and low volume sampling methods.
Table 9.1: Ambient air quality monitoring site for PM10 in Nelson, Tasman and Marlborough
9.2 PM10 concentrations
Concentrations of PM10 have exceeded the 24-hour ambient air quality guideline value in Nelson, Richmond and Blenheim (Table 9.2 and Figure 9.1). Of these areas, the highest concentrations and greatest number of guideline value exceedences have occurred in Nelson. Only one guideline value exceedence has been measured in Blenheim. Extrapolations of this measured data show that if monitoring was undertaken every day during the winter months, it is likely that more exceedences of the guideline value may have occurred at these monitoring sites.
Monitoring data for Nelson for 2001 also indicates that PM10 concentrations exceeded the annual average PM10 guideline value, with an annual average value of 36 µgm-3 being measured. This was estimated based on combining a summer and winter average to remove seasonal bias associated with the commencement of monitoring in March 2001.
Table 9.2: Summary of PM10 concentrations at ambient monitoring sites in Nelson, Tasman and Marlborough
Figure 9.1 shows the percentage of measured PM10 concentrations in Nelson, Richmond, Blenheim and Picton within the air quality categories. This shows a large percentage of the concentrations fall within the alert and action categories for the Nelson and Richmond sites. For the sites in Blenheim and Picton the majority of concentrations are within the good and acceptable categories. Although concentrations in Nelson and Richmond during 2000 appear worse than during 2001, the former monitoring periods included primarily the winter months (i.e. from May to September), whereas monitoring during 2001 was for the period March to December.
