Carbon monoxide in air

Monitoring sites

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

(Map source: LAWA)

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 was also 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 was collected continuously, several periods of missing data 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 was 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 was 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 was carried out using an Ecotech ML/EC 9830 CO analyser (gas phase infra-red absorption).

Monitoring results were 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

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

 

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

 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.)

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.

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).

Monitoring sites

The amount of nitrogen oxides produced by motor vehicles, industry and home heating were estimated for:

• Hamilton
• Tokoroa
• Te Kūiti
• Taupō
• Putaruru
• Matamata
• Waihi
• Te Awamutu
• Ngāruawāhia 
• Turangi.

Monitoring frequency

Emission summaries were completed for Hamilton, Tokoroa, Taupō and Te Kūiti every three to five years.

Monitoring history

The following table lists the years in which each town’s emission inventories were compiled.

Measurement techniques

Home heating

We estimated the amount of air emissions coming from home heating using household surveys. We asked people what they use to heat their home and the quantity and type of fuel they use, for example, gas or wood. We used this information to:

• estimate the amount of fuel used by different home heating appliances. For example, an open fire may burn about 20 kilograms of wood per day.
• estimate the amount of emissions given off by different home heating appliances and different types of fuel. For example, open fires emit about 100grams of CO per kilogram of wood burned.
• estimate CO emission rates, as grams of CO per kilogram of fuel burnt (g/kg). For example, a household burning 20 kilograms of wood per day on an open fire emits around2,000 grams of CO a day, based on an emission rate of 100 g/kg for an open fire.

Motor vehicle emissions

Waikato Regional Council used information from area-specific ‘local road network models’ to estimate the number and types of vehicles travelling in an area. Using the Ministry of Transport’s data for average vehicle emission rates, we estimated the amount of emissions coming from motor vehicles in a given area.

Industrial emissions

We used the information contained in resource consent files at Waikato Regional Council to estimate emissions from industry. Emission estimates were calculated based on daily fuel use or activity and the use of either average industrial emission rates for that process type or emission-specific information for the site. Where there was no New Zealand specific data, we used average emission rates from the United States.

Emissions of carbon monoxide from industry, vehicles and home heating were calculated as the daily winter average. The total daily emissions of CO (kg/day) from each source in an area were combined, and each source then calculated as a percentage of this total.

There were some variations in the methodology used in the 1997 and 2001 emission inventories. This made direct comparisons of results difficult.

Hamilton inventories for 2001 relied on the 1997 industrial emissions assessment, which were not re-evaluated in 2001. Tokoroa and Te Kūiti inventories for 2001 relied on the 1997 industry and motor vehicles inventories, which were not re-evaluated in 2001. Results for the 2004 inventories for Taupō, and Tokoroa indicate industrial emissions for 1997 were overestimated..