| Air Quality Standards and Guidelines | WNP Wharekirauponga Underground Mine - Assessment of Effects of Discharges to Air | 4397169-66885702-23 | | 27 4 Air Quality Standards and Guidelines 4.1 National Environmental Standards and Guidelines for Ambient Air Quality Ambient air contaminant concentrations may be compared with relevant criteria to assess the potential for adverse health and environmental effects to occur. The MfE Good Practice Guide for Assessing Discharges to Air from Industry (GPG Industry)9 sets out the order of priority for the use of various air quality assessment criteria as follows: ● Air quality standards contained in the Resource Management (National Environmental Standards for Air Quality) Regulations 2004 (NESAQ) ● New Zealand Ambient Air Quality Guidelines (AAQG) published by the MfE (2002) ● Regional Plan objectives (unless more stringent than above criteria) ● World Health Organisation (WHO) guideline concentrations (where appropriate) ● California OEHHA reference exposure levels (REL) (acute and chronic) and the US EPA inhalation reference concentrations and unit risk factors (chronic) ● Texas effects screening levels (if these have been derived from toxicological data in a transparent manner). The NESAQ Regulations set out ambient air quality standards for a number of contaminants including PM10, SO2, CO and NO2 for the protection of public health. The NESAQ and the AAQG are intended to apply where people are likely to be exposed for periods commensurate with the relevant assessment averaging period. The NESAQ and AAQG include both concentration limits and the specified number of occasions that these concentrations may be exceeded within any year. The Regional Ambient Air Quality Guidelines for Waikato are consistent with the AAQG and are not more stringent than the NESAQ or the AAQG. The NESAQ and AAQG that are relevant to this project are summarised in Table 4-1. The OEHHA chronic REL for respirable silica is also shown in Table 4-1. Table 4-1 Relevant air quality assessment criteria Contaminant Averaging period Threshold concentration µg/m3 Number of permitted exceedances Source PM10 24-hour Annual 50 20 1 - NESAQ AAQG CO 1-hour Running 8-hour 30 10 - 1 AAQG NESAQ NO2 1-hour 24-hour 200 100 9 - NESAQ AAQG Respirable silica Annual10 3 - OEHHA 9 Ministry for Environment (2016) Good Practice Guide for Assessing Discharges to Air from Industry 10 The annual guideline for silica of 3 µg/m3 is approximately equivalent to a 24-hour average guideline of 9 µg/m3. To convert concentrations for different averaging periods following power law equation Cn = Ct 2 (t2/t1) 0.2 is used. In this instance 9 ≈ 3 (365/1)0.2. Historically, the power law equation has been used in dispersion modelling assessments to estimate pollutant concentrations for different average periods when there was insufficient meteorological data to do so
RkJQdWJsaXNoZXIy MjE2NDg3