View all publications

5 Sources of PM10 in New Zealand

The results of the emission inventory investigations into sources of particles in New Zealand are shown in Figure 5.1. With the exception of Bay of Plenty, Taranaki and Gisborne, these data represent average wintertime emission sources. The main limitation with the assessment is the exclusion of sea spray emissions, as these may be a significant contributor in some of the coastal locations. Variations in the inclusion of some of the smaller emission sources are unlikely to significantly impact on results as all inventories include an assessment of the main anthropogenic contributors, domestic fires, motor vehicles and industrial emissions.

In Figure 5.1, results are presented for the main urban areas within the different regions. For areas such as Canterbury and Otago results are also available for many of the smaller urban towns (see Sections 2.6 and 2.8 and Table 5.1). In these smaller areas domestic fires are generally more dominant than for the larger cities of Christchurch and Dunedin. In contrast, results for some of the smaller north island areas (e.g. Tokoroa and Taupo), show a stronger industry component.

Table 5.1 shows estimates of PM10 and TSP discharges to air from different sources in kilograms per day and tonnes for per year. For the larger cities, PM10 emissions of around four to 30 tonnes per day are estimated, compared to around one tonne or less for most of the smaller urban areas. In Auckland, just less than 19 tonnes of PM10 is estimated from domestic heating per day compared to around eight tonnes for Christchurch and six tonnes for Wellington.

The relative contributions to PM10 emissions illustrated in Figure 5.1 and Table 5.1 are based on assumptions relating to emission rates and fuel use and contain some degree of uncertainty. There is some variation from area to area in the approach taken and the subsequent confidence in the results. The potential contribution of sea spray combined with concerns regarding methodological issues suggests that estimates of the relative contribution for Auckland illustrated in Figure 5.1 may not be appropriate.

The main source of particles within the urban areas of New Zealand is solid fuel burning for domestic home heating. However, industrial emissions also have the potential to be a significant contributor in a number of locations.

Table 5.1: Comparison of emissions estimates for different regions of New Zealand

 

  Domestic
kg/day
Mobile sources
kg/day
Industry
kg/day
    Total
kg/day

Alexandra

264

4

114

   

382

Arrowtown

120

0.5

14

   

135

Balclutha

250

4

17

   

271

Clyde

63

0.5

8

   

72

Cromwell

127

1

48

   

176

Milton

174

2

43

   

219

Mosgiel

325

3

290

   

618

Oamaru

870

17

236

   

1123

Queenstown

586

31

143

   

760

Wanaka

147

1

68

   

216

Dunedin

3174

101

1933

   

5208

  Domestic heating
kg/day
Motor vehicles
kg/day
Industry
kg/day
Other domestic
kg/day
Other mobile
kg/day
Total
kg/day

Christchurch

7929

991

1027

   

9947

Rangiora

543

8

61

   

612

Kaiapoi

334

12

5

   

351

Ashburton

897

18

106

   

1021

Waimate

285

1

6

   

292

Timaru

1124

61

41

   

1226

Hamilton

3600

371

39

   

4010

Taupo

409

77

866

   

1352

Tokoroa

1232

58

2866

   

4156

Nelson

1486

78

264

85

 

1912

Northland

3028

633

1915

103

 

5679

Auckland

18,900

2000

7100

300

700

29,000

  Domestic/ commercial heating
kg/day
Motor vehicles
kg/day
Industry
kg/day
Other domestic
kg/day
Other mobile
kg/day
Total
kg/day

Wellington

6160

1200

2000

180

490

10,030

  Domestic
t/year
Mobile sources
t/year
Industry
t/year
Burn-offs
t/year
  Total
t/year

Taranaki

490

251

138

   

879

BOP

1110

455

849

323

 

2737

Gisborne

151

58

340

210

 

759

Figure 5.1: Relative contribution of sources of particles within New Zealand