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  Environment » Environmental Information » Environmental indicators » Air: monitoring and reporting » Carbon monoxide levels in air » Methods - how we monitor

Methods - how we monitor

Where and how we collect the data

Waikato Regional Council measures carbon monoxide levels in Hamilton. We suspect Hamilton to be at risk from carbon monoxide because of the density of housing and levels of traffic.

Monitoring sites

Monitoring sites for this specific indicator are marked in blue below:

(Map source: LAWA(external link))

Carbon monoxide was monitored in Hamilton at Waikato Regional Council's Peachgrove Road monitoring site over the period 1998 to 2005. This is classified as a residential peak monitoring site in accordance with the Ministry for the Environment’s air quality monitoring site classifications.

Carbon monoxide has also been monitored in Hamilton at Waikato Regional Council’s Ohaupo Road monitoring site over the periods 1 October 2012 to 31 March 2013 and 6 March 2014 to 10 June 2014. This intersection was selected on the basis of it having been identified as a busy traffic site.

Monitoring frequency

Carbon monoxide concentrations are measured continuously and are logged as 10 minute averages. Hourly and eight hour averages are derived from 10 minute data.

Monitoring history

Carbon monoxide monitoring commenced at the Peachgrove Road site in November 1997 and finished in July 2005.

While data are collected continuously, several periods of missing data have occurred. The largest of these are:

  • November 1 to December 22, 1998
  • October 5 to November 17, 1999
  • January 22 to February 13, 2001
  • August 29 to September 16, 2002
  • February 24 to March 19, 2003
  • April 18 to May 18, 2003
  • February 24 to March 18, 2004
  • April 17 to May 17, 2004.

More recently, carbon monoxide has been monitored continuously at the Ohaupo Road monitoring site over the short survey periods 1 October 2012 to 31 March 2013 and 6 March 2014 to 10 June 2014.

Measurement technique

Monitoring is carried out using an advanced pollution instrumentation (API) analyser. This is a continuous analyser that measures carbon monoxide concentrations using gas-phase infra-red absorption.

The more recent monitoring at the Ohaupo Rd site has been carried out using an Ecotech ML/EC 9830 CO analyser (gas phase infra-red absorption).

How this indicator is compiled

Monitoring results are reported in relation to the Waikato Regional Plan, using the Ministry for the Environment air quality indicator reporting framework outlined in the table below. This framework is used to report on air quality for a range of contaminants relative to their respective guidelines.

Table 1: Ministry for the Environment categories for air quality

Category Value relative to guideline Comment
Excellent Less than 10% of the guideline Of little concern
Good Between 10% and 33% of the guideline Peak measurements in this range are unlikely to affect air quality
Acceptable Between 33% and 66% of the guideline A broad category, where maximum values might be of concern in some sensitive locations but generally they are at a level which does not warrant dramatic action
Alert Between 66% and 100% of the guideline A warning level, which can lead to the guideline being exceeded if trends are not curbed
Action More than 100% of the guideline Exceeding the guideline is a cause for concern and warrants action if it occurs regularly

 

Tables 2 and 3 show the percentage of times carbon monoxide levels fell into each category and the maximum level for the year of monitoring.  

Table 2: 1998-2014 one-hour carbon monoxide levels at Hamilton

Year Categories 99.7
%ile1 (mg/m3)
Maximum value (mg/m3) Number of times levels exceeded the proposed regional guideline
Excellent Good Acceptable Alert Action
1998 98% 2% 0% 0% 0% 7 9 0
1999 99% 1% 0% 0% 0% 4 7 0
2000 100% 0% 0% 0% 0% 4 5 0
2001 98% 2% 0% 0% 0% 8 9 0
2002 99% 1% 0% 0% 0% 6 10 0
2003 99% 1% 0% 0% 0.0 6 7 0
2004 97% 3% 0% 0% 0% 7 9 0
2005 98% 2% 0% 0% 0% 4 6 0
2012 100% 0% 0% 0% 0% 1 1 0
2013 100% 0% 0% 0% 0% 1 1 0
2014  91% 9%  0% 0% 0%  3  5 0

 

Table 3: 1998-2014 8-hour carbon monoxide levels at Hamilton

Year Categories 99.7
%ile1 (mg/m3)
Maximum value (mg/m3) Number of times levels exceeded the proposed regional guideline
Excellent Good Acceptable Alert Action
1998 84% 16% 1% 0% 0% 5 5 0
1999 92% 7% 0% 0% 0% 3 4 0
2000 97% 3% 0% 0% 0% 2 3 0
2001 86% 13% 2% 0% 0% 7 7 0
2002 88% 12% 0% 0% 0% 4 5 0
2003 93% 6% 1% 0% 0.0 5 5 0
2004 84% 14% 1% 0% 0% 6 7 0
2005 81% 18% 0% 0% 0% 3 4 0
2012 99% 0% 0% 0% 0% 1 1 0
2013 100% 0% 0% 0% 0% 1 1 0
2014 100% 0%   0%  0% 0%   2  3 0

 

Guidelines and standards

National ambient air quality guidelines for carbon monoxide are:

  • 30 mg/m3 – 1-hour average.
  • 10 mg/m3 – 8-hour average.

National Environmental Standard for Air Quality for carbon monoxide is:

10mg/m3 - 8-hour average (1 allowable exceedance per year.)

Limitations

Waikato Regional Council has carried out carbon monoxide monitoring in Hamilton only. Results from Hamilton suggest that carbon monoxide concentrations in other areas are unlikely to be of concern.

 

Quality control procedures

Waikato Regional Council, 1999: Environmental Monitoring Technical Manual. Waikato Regional Council, Hamilton. (unpublished).

Environment Waikato, 2003: Quality Assurance Procedures Manual for ambient air quality monitoring at Environment Waikato. Environment Waikato, Hamilton. (unpublished).

Footnotes

  1. The 99.7 per cent value is the highest value recorded for 0.3 per cent of samples. Compared with the recorded maximum value this provides more information about extreme values.

Updated June 2014

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