The air quality in New Plymouth was continuously monitored in a programme which ran from 9 January to 28 May 2010.
The graph below summarises the results of the monitoring (click on the graph to see a big version).
Results of New Plymouth air monitoring, January-May 2010. Click on graph for big version.
How is air quality measured? What is PM10?
Scientists use filtering equipment to take air samples, then measure the number of tiny particles, known as Particulate Matter (PM), it contains. PM is potentially dangerous because it can penetrate deep into the lungs, causing illnesses such as cancer, and premature death. Particularly at risk are people with existing lung, heart and blood-circulation conditions such as asthma and chronic pulmonary diseases.
PM has diverse chemical and physical characteristics, and can vary in size. Its diameter is measured in microns (millionths of a metre, abbreviated as µms). The air quality standards focus on PM with a diameter of less than 10µms. This standard is known as PM10.
PM with a diameter of less than 10µms is incredibly tiny — five times smaller than the diameter of a human hair, It can remain in the air for several days and can be spread by winds over wide areas. It is invisible to the human eye.
Under the Ministry for the Environment's National Environmental Standard, every cubic metre of air should contain no more than 50 micrograms (50 millionths of a gram) of PM10, averaged over 24 hours, and with only one breach allowed in a year. This standard is to be achieved nationwide by 2013.
Where does PM come from?
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Fine particles magnified thousands of times. Top row: Carbon, pollen and road dust. Left: Pollen and sea salt. Photos: University of Auckland |
There are many sources of PM, including motor vehicles (particularly diesels), wood and oil-burning processes and coal-fired power generation, incineration and waste burning (rubbish or vegetation), smog, and natural sources such as pollen, rock-dust and sea-spray.
Earlier PM10 surveys in New Plymouth have detected:
- Salt crystals (sodium chloride).
- Mineral material (e.g. soil, silt, clay dust).
- Other crystals - possibly calcium sulphate (gypsum).
- Seeds, spores and pollen (mainly spores from fungi).
- Combustion particles.
Why was air quality in New Plymouth monitored?
The Government has set a national standard for air quality, and requires Regional Councils to demonstrate that air meets the standard.
Taranaki has now demonstrated this in four surveys, the last in 2010. Samples have never exceeded air quality guidelines, always falling into the Ministry for the Environment's categories of "acceptable" to "excellent".
On this basis, general air quality monitoring is not a high priority for the Taranaki Regional Council.
We still carry out general surveys from time to time but our main focus is regularly monitoring of the region's emission sources.
Please contact us if you have comments or questions.