A near carless Fenton St on the first day of the level 4 lockdown. Photo / File
There aren't many upsides to a global pandemic that forced people to stay home and ground economies to a halt, but improvements to air quality are one silver lining recorded in cities all over the world, including Wellington and Auckland. But did anything change in Rotorua?
Fewer cars on the road, a slowed industrial sector and a five-week lockdown have made next to no difference to particle pollution in Rotorua, raw data shows.
Data from four Bay of Plenty Regional monitoring sites around the region showed little change in levels from PM10 - tiny particles that can be inhaled - compared with previous years.
And while Auckland and Wellington have reported significant decreases in pollution from vehicle exhausts, comparable data is not available for the Bay of Plenty.
Bay of Plenty Regional Council coastal land and air science team leader Shane Iremonger said PM10 was the focus of the council's air quality monitoring.
Five times smaller than the width of a human hair, these specks of matter include any particle - solid or liquid - that can be inhaled.
Found in the likes of dust, pollen, mold, sea salt and vehicle emissions, PM10 can harm human health.
The council compared raw data collected from four sites around the region - including one in Edmund Rd, Rotorua, from during the first four weeks of the lockdown.
Iremonger said the lockdown results - taken from March 26 to April 22 - were similar to those of previous years.
"[This suggests] there has not been any significant reductions in PM10 as a result of alert level 4 restrictions."
He said the lockdown data had not been through the usual quality assurances yet, so caution should be applied to any conclusions.
Asked what might be behind the lack of lockdown impact, he said more information was needed to draw conclusions about PM10 sources during the period.
"Further analysis is planned to correlate our air quality information with other meteorological or activity data such as roadway traffic counts, port activity, industrial site (essential business) operations or domestic heating."
He said the council's monitoring focused on fine particles and a range of other air contaminants related to odour, fumigation, shipping, port activities and industrial processes, as those were the main issues and activities for the council and its communities.
"Historically we have measured nitrogen oxides but the values were low so discontinued.
"We have the capability to measure nitrogen oxides at some time in the future should the focus of our investigations change for any reason."
Dr Ian Longley, an air quality researcher with the National Institute of Water and Atmospheric Research (Niwa), said most councils did not measure nitrogen oxides.
He analysed monitoring of nitrogen oxides in Auckland and Wellington and found levels had dropped to between 83 and 91 per cent of normal at most sites by the third week of lockdown.
Levels of PM10 at most sites in Auckland rose between the first and third weeks of lockdown, but remained below normal.
He attributed the change over lockdown to stronger winds and the normal expectation of a rise in April due to the start of home heating season.
He said the Bay of Plenty's lockdown PM10 results were "consistent with what we're seeing all over the country".
Like Auckland, most emissions of PM10 in Tauranga and Rotorua were not from traffic, so are "not expected to be affected much or at all by lockdown".
Experts only expected the traffic portion to fall significantly, leading to an overall drop in PM10 of about 10 per cent.
"That's exactly what we've seen in Auckland."
It was not possible to verify such a small change in the Bay of Plenty data provided by the council due to the formatting, he said.
The data for Rotorua showed a rise over the four-week period, while remaining in the normal range.
In Rotorua, most of the air quality analysis in recent years has centred on winter PM10 emissions from home heating.
As of January 31, all wood burners installed before September 2005 have to be replaced.
Earlier in the year, heating installers reported a rush of orders, but that work came to a halt during the lockdown.
Rotorua resident Kay Richards, office manager for The Fireman, said that while sales of fires had continued in lockdown, installations had stopped unless essential.
With most people still staying home, she expected there would be a slight increase in emissions as people could use their fires during the day when they would usually be at work.
"I've had my fire going most evenings."
The Rotorua data was collected at Edmund Rd, where the monitoring focused on domestic emissions, such as woodsmoke, and minor urban traffic emissions.
Residential data was also collected in Kopeopeo in Whakatāne and Otumoetai Rd in Tauranga, while industrial data monitoring a wider range of emissions sources was collected in Totara St in the Mount Maunganui industrial area.
• Covid19.govt.nz: The Government's official Covid-19 advisory website
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