The National Environmental Standards for Air Quality (NESAQ) set the limits for certain pollutants that are known to have adverse effects on health.  One of these pollutants is particulate matter (fine dust).  Although all particulate matter can have an adverse effect, the particulates that are of specific concern are those of ten micrometres in diameter or less.  Five of these particles could fit across the width of a strand of human hair.  These particulates are known collectively as PM10 and are inhalable into the windpipe and bronchial tubes of the lungs.  The NESAQ has set the limit for PM10 at 50 micrograms per cubic metre (50µg/m3) expressed as a 24-hour mean.

The Standards have set the deadline of September 2013 as the time when the Rotorua Local Air Management Area (LAMA) is required to comply with the PM10 standard.  If this is not achieved, Environment Bay of Plenty will be prevented from granting resource consents for discharges to air from industry within the designated LAMA. 

To read the standards, see the website for the Ministry for the Environment.

Over fifty percent of all home heating in Rotorua is from burning solid fuel in woodburners, open fires, or multi-burners.  The emissions from these fires contribute to sixty percent of all winter time PM10 emissions (see Figure 1 below).  As winter is the season when all of the exceedences are measured in Rotorua, home heating is the primary cause of the exceedences.  Initiatives to solve the problem will therefore focus on home heating, however all discharges will be looked at for improvements.

One of the reasons for the large contribution is the age of woodburners currently in use in Rotorua.  Thirty three percent of all woodburners currently in use are at least 17 years old, as shown in Figure 2 below.  A further 19 percent of people do not know how old their woodburner is, therefore there is potential that even more woodburners are of excessive age. Older woodburners are generally less efficient than new ones therefore their contribution to the particulate problem is greater.

This information is a summary of two investigations that have been carried out in Rotorua: 

Rotorua Domestic Heating Survey (395KB, pdf)

Rotorua Air Emissions Inventory 2005 (4.7MB, pdf)

Rotorua LAMA – Straight Line Path Report (251KB. pdf)

Rotorua Airshed Modelling Investigation Final Report (6.4MB)

Environment Bay of Plenty and the people of Rotorua have until 2013 to solve the particulate problem.  A project team and working party has been set up to address the issues and come up with possible solutions.  An Action Plan is currently being worked on and is expected to be completed by the end of 2007 or sooner.  A part of the Action Plan is to use advanced airshed models to examine the pattern of particulates in Rotorua to work out actions to reduce the emissions of PM10.
 
Other initiatives to reduce PM10 emissions are being investigated.  These will be brought on stream as they are finalised.

- Having a warm dry home is just as important as having clean air to breathe, and we don’t want to sacrifice one for the other.  So if your woodburner is your main source of home heating then continue to use it.  However, there are some easy things that you can do to reduce your emissions to the environment and increase the efficiency of your fire.

- Stock up on firewood 6-12 months before winter to ensure your firewood is well seasoned and store it in a dry place. Burning wet wood increases emissions. 

- Don’t burn driftwood, treated wood, or painted wood.  These all release dangerous chemicals to the atmosphere.  Also, don’t burn rubbish.  Use the refuse and recycling facilities provided by the Rotorua District Council.  

- Burn smaller hotter fires.  They are more efficient.  Avoid letting the fire smoulder, either by overloading it, or dampening down, especially overnight.  This causes more emissions so it’s better to relight your fire in the morning if needed.

- If you are thinking of changing your woodfire, there are several options available:

- Upgrade to a new woodfire.   All woodfires installed must now comply with the standard, and will not get a building consent from Rotorua District Council if they do not comply.  A list of compliant woodburners can be found on the website for the Ministry for the Environment.

- Replace your woodburner with a heat pump.  Heat pumps are efficient, easy to use and no more chopping or carrying wood is necessary.  They also have the advantage of a timer, which means you can wake up or arrive home to a warm house; no mess, no fuss.

- Pellet fires are a good alternative to a woodfire.  They are efficient and very clean burning, and once again you don’t need to worry about the manual labour involved with firewood.  They only use purpose made pellets though, so no more free firewood can be used.

- Gas heating is still widely used and can be an efficient way to heat your home.  Take care with gas though, because if your heater is unflued it is extremely bad for your health.  See the website for the Ministry of Health.  Keep in mind also that gas is a non-renewable resource.

- Geothermal energy is an excellent source of renewable heat.  Unfortunately, the geothermal field is limited to one small part of Rotorua.  To make it more accessible to large parts of the community, extensive (and expensive) reticulation is required.  Even if you do live within the active zone, setting up a bore is extremely expensive.  However, some may find that converting to geothermal energy for home heating is a viable option in the future.

- Smarter Homes has a website that can help you assess your home.  It has advice on how to make your home cheaper to run, more comfortable to live in, and more environmentally friendly. 

While we want to solve the problem of particulates, it’s important to keep sight of the bigger picture, particularly with regard to using renewable energy and limiting carbon discharges.  If you are concerned with climate change and want to do your bit, then choosing the right heating system will be important to you.

Using electricity to heat your home is the cleanest option available, especially when used in very efficient appliances such as heat pumps.  However, while there are no local effects of increased electricity use, there are global effects.  Most of New Zealand’s electricity is generated using renewable, carbon neutral methods.  However, there is still some reliance on non-renewable thermal generation using gas or coal.

Fortunately, we have a choice of which electricity provider we use.  To find out which ones are the greenest and sourced from carbon neutral generation, check out the Clean Energy Guide website.

If you have any enquiries or suggestions, feel free to contact Environment Bay of Plenty on 0800 ENV BOP (368 267) or email us at info@envbop.govt.nz.