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The air that we breathe

Gisborne's air quality has been breached seven times since the last breach on June 10.

The allowed amount of particulate matter (PM) in the air is 50 micrograms per cubic metre of air.

Breaches were recorded on July 4 (54.8mg), July 10 (53.2 mg), July 25 (65.7mg), July 27 (58.3mg), July 29 (53.5mg), July 30 (83mg) and the latest was yesterday at 73.6mg.

Particulate matter is a mixture of extremely small particles and liquid droplets.

Gisborne District Council team leader of monitoring and compliance Kate Sykes said air quality had not suddenly deteriorated this year.

“These exceedances are likely due to the installation of new equipment, which is more sensitive.

“It would be difficult to determine whether the old equipment under-reported or the new equipment over-reports the levels, but if the air is noticeably smoky at night or very early in the morning. it is likely to be polluted with particulate matter.”

GDC's air quality monitoring system was installed at Gisborne Boys' High School in 2004 in an enclosure to protect it from the weather.

Two standards of measurement are used for air quality monitoring — PM10 and PM2.5.

PM10 refers to small airborne particles less than 10 micrometres across.

These particles can easily be inhaled and the largest particles can get trapped in the nose and nasal passages and cause irritation.

PM2.5 are tiny airborne particles less than 2.5 micrometres across, and are a component of PM10.

It can be easily breathed deep into the lungs where the smallest particles can enter the bloodstream.

Regulation 16 of the National Environmental Standard for Air Quality doesn't require notification every time a breach happens, but must be given periodically, at least once a month until the standard is no longer being breached.

“We are aware from some work we did in 2018 that there are spatial difference throughout the city suburbs. This is due to topography and land features and this means some areas are more affected than others,” Ms Sykes said.

“What is apparent is that clear, cold nights with light winds are likely to breach the standard.

The national environmental standard was being revised by the Ministry for the Environment and consultation closed last week.

“Any changes required from this review will be implemented in conjunction with the review of the Tairawhiti Resource Management Plan which council recently agreed to begin,” she said.

Hauora Tairawhiti medical officer of health Dr Osman David Mansoor said air quality was a risk factor for many health conditions, “particularly those that affect the respiratory system and the heart”.

“That is why air quality must be monitored, and that is the responsibility of the council.

“Generally air quality in Tairawhiti is good and has not been decreasing. However, Hauora Tairawhiti will keep an eye on any breaches to look for trends,” Dr Mansoor said.

Gisborne District Council usually updates its website within two days of a breach.

“Since the exceedances started this year we have added more information to the website to provide tips on how households can help,” Ms Skyes said.

• These tips can be found on: www.gdc.govt.nz/air-quality or www.gdc.govt.nz/air-quality-in-winter/

WHAT READS THE AIR: Gisborne District Council's air quality monitor, a Teledyne T640x, which is used by many regional councils around the country. It uses a light scattering spectrometry approach to determine the amount of particulate matter in the air and the size of the particles. Picture by Liam Clayton