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The primary purpose of this research was to improve our understanding of the impacts that dust emissions from unsealed roads have on people and investigate dust mitigation measures. The project’s key research objectives were:

1. Characterise the dust and quantify the impacts of dust from unsealed roads on people.
2. Determine the effectiveness and cost of dust mitigation measures.
3. Estimate the costs of the health impacts of dust and estimate the benefits of mitigating the dust.
4. Propose a methodology to support decision making about mitigation options.

A two month road dust monitoring campaign was undertaken on a section of Mataraua Road, 10km southwest of Kaikohe in the Far North District, during February, March and April 2015.

The monitoring results indicated that potential adverse human health impacts might occur due to the dust discharged from untreated unsealed roads. A comparison of the PM10 concentrations monitored at the untreated and treated sites showed that the application of a dust suppressant significantly reduced the impact of dust discharged from the road.

Keywords: dust PM₁₀, dust suppression, health effects, unsealed roads.

Changes made to version of report published in August 2016

• Order of authors changed to more accurately reflect the relative effort contributed.
• Page 8, paragraph five of the Executive summary – edited to include the 10 year cost estimate.
• Page 8, paragraph six of the Executive summary - edited to update the BCR values as a result of corrected health cost calculations.
• Page 68, table 6.2; page 69, tables 6.3 and 64.  Values in all three tables have been updated to reflect corrected health cost calculations.
• Page 69, paragraph 1 - updated BCR values transcribed from updated tables 6.3 and 6.4.
• Page 70, paragraph 1 - number of years a sealed road needs to be used to get a BCR of 1 updated as a result of the revised health costs.
• Page 77, paragraph 2 – information in parenthesis, approximate percentage of days monitored, deleted.
• Page 78, section 8.3 - updated BCR values transcribed from updated tables 6.3 and 6.4.
• Page 95, Appendix D2, Benefit assumptions - corrected health cost calculations incorporated.
• Page 97, Appendix D7, Health costs from dust - corrected health cost calculations incorporated.

In the original version of the report, Golder had incorrectly presented the health costs calculated for the Kiakohe CAU rather than the Ngapuhi-Kaikou CAU within which Mataraua Road is located. A review by Emission Impossible Ltd highlighted the issue and enabled Golder to amend the report. We acknowledge this error and appreciate the opportunity to correct it.

Incorporating the correct health cost calculations into the report has resulted in a slight change to the conclusions. The BCR values have changed (improved) as follows:

• treating the surface of the road with chemical suppressant - BCR has gone from 0.8 to 1.1.
• sealing the surface of the road (40 year use) - BCR has gone from 1.4 to 1.9.
• sealing the surface of the road (10 years use) - BCR has gone from 0.7 to 0.9.