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2 Statement of the Issue
2.1 Objectives for ambient air quality
The Minister for the Environment has determined five main objectives for national policy development for air quality management in New Zealand:
- to improve consistency in policy and legislation in relation to ambient air quality
- to improve air quality where it is degraded and reduce the health impacts of poor air quality
- to provide a level playing field across New Zealand
- to provide certainty and equal treatment for all New Zealanders
- to ensure certainty for entrant industry.
2.2 Improving our air quality
On the whole, New Zealand has relatively good air quality due to our low population density, close proximity to the sea, and remoteness from other continents and sources of pollution. However, concentrations of fine particles are quite high in some urban areas, especially during low wind conditions where home heating is mainly by open fires or poorly performing wood burners, and where there is high traffic density.
The Ministry for the Environment, in response to this situation and calls from various sectors, wants to introduce a series of national standards to address fine particle pollution, and other priority contaminants such as CO, NO2, O3 and SO2 before they increase to a level that will result in adverse health effects.
In its Sustainable Development for New Zealand: Programme of Action announced in January 2003 (Department of Prime Minister and Cabinet, 2003), the Government noted the importance of improving air quality as an element of creating "liveable cities that support social wellbeing, quality of life and cultural identities". A key step in developing liveable cities was identified as:
Developing environmental standards (for air quality, water quality, noise and waste) and a timetable for their implementation, in consultation with urban authorities.
One key aspect of improving our air quality is reducing New Zealanders' exposure to dioxins. Dioxins are highly toxic chemicals that are known to cause serious health effects such as cancer, birth defects, and reproductive and developmental problems. Once in the environment, dioxins accumulate in the fatty tissue of wildlife, livestock and people. They break down only very slowly and can remain in the environment and in the bodies of animals and people for a very long time.
A major portion of the dioxin that enters the body of the typical New Zealander originates as a discharge to air and is eventually ingested in meat and dairy products.
In October 2001 the Minister for the Environment announced New Zealand's action plan for reducing discharges of dioxin to air (Ministry for the Environment, 2001a), which proposed developing a national environmental standard to reduce dioxin discharges to air. The prohibitive activity standards proposed as part of the current package of national environmental standards reflect many of the recommendations made in the Dioxin Action Plan and are intended to reduce exposure to dioxins as well as other toxic pollutants.
The existing Ministry for the Environment Ambient Air Quality Guidelines (Ministry for the Environment, 2002a) have no legal status. National environmental standards are therefore seen as a more effective way of providing protection for New Zealanders from the health risks of air pollution and dioxins. Parameters selected for the proposed standards will use the existing guideline values as the ambient standard values. Parameters contained in the Ambient Air Quality Guidelines that are not included within the standards are still appropriate to use as best-practice guideline levels.
The prohibitive activity standards (bans) are regarded as the most efficient and effective way to provide protection for all New Zealanders from the health and environmental effects of dioxins and other toxic chemicals.
2.3 Greater protection and certainty
Over the past 10 years the Ministry for the Environment has provided guidance to local government on managing air quality through a series of guidelines. While the levels of some contaminants in our air have declined (such as the decrease in air lead levels with the phasing out of leaded petrol), concentrations of other pollutants appear to be increasing. Where measures are already under way to improve air quality in towns and cities, the standards should strengthen or give greater weight to these efforts. Where there is currently limited action under way, new measures may provide the required boost.
The current system of guideline values has created a range of requirements within plans, monitoring programmes and discharge permits where industries and communities may face different rules in different regions. It has also created an environment where litigation of the same issues occurs region by region. This causes an uncertainty that can confuse industries and communities and potentially results in delays in consent processing and plan development.
It therefore makes sense to ensure that all discharges to air meet a certain standard throughout the country and to establish the same regulation and protection for all New Zealanders. There have been calls by industry, councils and others for the government to develop national environmental standards to improve consistency and set the environmental bottom lines for air quality.
The Minister for the Environment considers that action is needed to protect air quality for all New Zealanders and to give greater certainty for planning and resource consents.
2.4 Air pollution
2.4.1 Overview
A number of reports prepared by the Ministry for the Environment deal with the health and environmental effects of air pollutants. While some aspects of our air quality are improving, the concentrations of other pollutants, especially from vehicle emissions, are increasing. There is evidence that air pollution in some towns and cities is causing adverse effects on people's health and wellbeing and needs to be improved.
While many New Zealanders believe that our air quality is good, surveys show that the majority perceive a decline in the last five years. This perceived deterioration is matched by a demand for more expenditure on air quality (Hughey et al, 2003).
The key air pollutant of concern in New Zealand is fine particles (PM10 - particles less than 10 microns in diameter). Action is also required to prevent other pollutants such as CO, NO2, O3, SO2 and dioxins from increasing to levels at which they become a concern.
Fine particle pollution in some of New Zealand's urban areas is causing serious adverse effects on people's health, including premature deaths, respiratory diseases, asthma attacks, reduced immunity, and coughs and wheezing. In turn, these health impacts affect people's ability to work and play, hasten their deaths, and burden the health system.
The Ministry now has partnership agreements with all regional councils for monitoring fine particle pollution.
2.4.2 Fine particles (PM10)
The science underpinning our understanding of the health impacts of particles is epidemiology. [The branch of medicine that deals with the study of the causes, distribution, and control of illness in populations.] Observational studies on the relationship between concentrations of particles and health effects have been conducted in many countries, and numerous locations throughout the world. The results show that increases in mortality and other health effects are associated with increases in 24-hour average PM10 concentrations. The consistency and coherency of the studies have led researchers to conclude that fine particles cause these health effects and that there is no threshold below which effects do not occur.
The impact of PM10 concentrations on the health of residents in different areas of New Zealand has been estimated in a number of different studies. The most extensive study was carried out by Fisher et al (2002), and estimates the number of premature deaths associated with PM10 concentrations from all sources and from motor vehicles based on relationships described in a study by Kunzli et al (2000). Results are reported for the four major cities (Auckland, Christchurch, Wellington and Dunedin), with other areas being collated for both the North and South Island. The estimated annual premature mortality rates were: 440 for Auckland, 180 for Christchurch, 80 for Wellington, 50 for Dunedin, 40 for Hamilton and 20 for Nelson.
See figure at its full size (including text description).
Risk assessments of the impact of PM10 concentrations in Christchurch and Nelson have been carried out (Hales et al, 1999), as have studies of the health impacts of PM10 in Christchurch (McGowan et al, 2002). These studies include mortality estimates as well as hospitalisations and restricted activity days (RADs). The mortality estimates for the latter risk assessments underestimate mortality by around four to five times compared to Fisher et al (2002). This is attributed to the time-series methodology of the Hales et al (1999) study, which associates only those deaths that occur a relatively short time after the pollution episode to PM10 concentrations. Thus they are limited to a selection of the acute impacts but do not estimate the reduced life expectancy due to long-term morbidity enhanced by air pollution.
Results from an analysis undertaken for the Ministry for the Environment (2003b) indicate a range of estimated hospitalisations per year in the larger cities, from around 25 in Dunedin to 200 in Auckland. Estimates of RADs in New Zealand cities range from around 90,000 per year in Dunedin to around 750,000 in Auckland. Figure 2 and Table 1 show the extent of the estimated particles problem across New Zealand.
Table 1: Estimates of health impacts of particle concentrations in New Zealand
View estimates of health impacts of particle concentrations in New Zealand (large table)
The majority of PM10 monitoring in New Zealand is carried out on a one-day-in-three or one-day-in-six basis. This means that PM10 data are not collected every day of the year. Table 2 summarises the available PM10 data in New Zealand. From this we can see that:
- five locations have measured levels in excess of 120 µg/m3
- 36 monitoring stations in 28 urban areas have measured exceedances of the daily guideline
- 11 locations have measured more than five exceedances of the daily guideline.
As mentioned above, monitoring is not carried out every day. For the data presented in Table 2 monitoring was performed on average 39% of the days of the year. If monitoring were to be carried out every day it is estimated that most areas (29 of the 36 monitoring locations) would exceed the proposed daily guideline more than five times per year.
Table 2: Maximum measured concentrations of PM10 (24-hour average) in New Zealand compared with the daily guideline
View maximum measured concentrations of PM10 (24-hour average) in New Zealand compared with the daily guideline (large table)
See figure at its full size (including text description).Source: Ministry for the Environment, 2003d
2.5 Other pollutants
In most areas of New Zealand, concentrations of SO2, CO, NO2 and O3 are below their respective ambient air quality guideline values (Ministry for the Environment, 2002a). Exceptions to this are concentrations of CO in the ambient air in Christchurch, as well as roadside concentrations in Auckland, Christchurch, Wellington and Dunedin and roadside concentrations of NO2 in Auckland.
The main concern with these pollutants is to maintain or improve the current situation and avoid them increasing to levels that would cause adverse health and environmental impacts.
2.5.1 Sulphur dioxide (SO2)
Ambient air quality monitoring for SO2 in New Zealand is largely limited to monitoring carried out in Canterbury, the long-term monitoring site in Penrose (ACI) in Auckland, Hawke's Bay, and around some industrial sources. In addition, survey-type monitoring has been carried out in Taranaki, the Bay of Plenty and Otago. No guideline exceedances for SO2 were measured at these locations between 1992 and 2002.
Data for Christchurch from 1992 to 2001 shows there have been no exceedances of the proposed national standard of 350 µg/m3 as a one-hour average (the maximum reading has been 334 µg/m3). In other areas of Canterbury, concentrations are typically below 100 µg/m3. In Auckland (Penrose) and around some industrial sites, one-hour average SO2 concentrations measured up to 165 µg/m3. The limited amount of SO2 monitoring that has been carried out in other parts of New Zealand does not indicate concentrations of concern.
Monitoring around a Ravensdown site during 1996/97 showed levels approaching 50% of the proposed standard level, but levels have dropped considerably after the shutdown of the sulphuric acid plant.
2.5.2 Nitrogen dioxide (NO2)
Concentrations of NO2 have been monitored in Auckland, Waikato, Hawke's Bay, Wellington, Canterbury and Nelson. In addition, survey-type monitoring has been carried out in Taranaki, the Bay of Plenty and Otago. Most of the time concentrations of NO2 are 'excellent' or 'good' in these locations.
The main exception is the Khyber Pass Road monitoring site in Auckland, where NO2 concentrations regularly exceed guideline values. No guideline value exceedances for NO2 (24-hour average) have been measured at residential air quality monitoring sites.
The guideline values for NO2 for New Zealand are based on a safety factor of 50% applied to the lowest observable adverse effect level for the protection of sensitive groups, including children and asthmatics and people with chronic respiratory and cardiac disorders (Ministry for the Environment, 2002a).
Because the maximum one-hour average NO2 concentrations measured at Khyber Pass Road are over twice the guideline value, it is possible that sensitive individuals in this area will suffer health affects as a result of NO2 exposure. It is also possible that adverse health effects may occur as a result of NO2 exposure close to other roadsides within Auckland (e.g. Dominion Road). In other areas of New Zealand, ambient air concentrations of NO2 do not breach the guideline values and are unlikely to be causing adverse health effects.
2.5.3 Carbon monoxide (CO)
Air quality monitoring of CO has been carried out in Auckland, Waikato, Hawke's Bay, Bay of Plenty, Wellington, Canterbury, Otago and Nelson. Most of the time concentrations of CO are 'excellent' or 'good' in most of these locations.
However, the guideline values are regularly exceeded at the Khyber Pass Road traffic site and at residential monitoring sites in Christchurch. Long-term monitoring for CO at Queen Street in Auckland and St Albans in Christchurch indicates concentrations of this contaminant have decreased between 1992 and 2001.
There may be some health affects as a result of exposure to CO concentrations in Christchurch and near to roadsides in Auckland and Wellington, including a significant decrease in work capacity in healthy adults, decreased exercise capacity at onset of angina, and increased duration of angina in people with ischaemic heart disease. Similarly prolonged exposure to concentrations measured at these sites and other sites (e.g. Dominion Road and Khyber Pass) could impact on developing foetuses, resulting in reduced birth weight in non-smokers.
2.5.4 Ozone (O3)
Air quality monitoring for O3 has been carried out at a number of locations within Auckland and at two sites on the outskirts of Christchurch. Two exceedances of the eight-hour guideline value occurred at Musick Point in Auckland during October 2002. In other locations, guideline values have not been exceeded, although a large proportion of the data were within the 'acceptable' category and in Auckland up to 15% of the data were in the 'alert' air quality category.
An estimate of the impact of O3 concentrations on mortality in Auckland indicates that over 100 deaths per year may be attributable to exposure to O3. Concentrations of O3 in Auckland were in excess of the ambient air quality guideline values at one monitoring site. No estimates were made for Christchurch because of the large uncertainties surrounding exposure.
2.6 Dioxins and other toxic substances
Some activities cause local pollution by toxic materials, including dioxins. Studies carried out by the Ministry for the Environment show that the background levels of dioxins in the New Zealand environment, and in our foods, are generally low compared with many other countries. Nevertheless, even a low level of dioxins in our environment accumulate in people's bodies. An independent report on the health risks of dioxin concluded that the current background exposures to dioxin-like compounds for the New Zealand population has an insufficient margin of safety and steps should be taken to further reduce exposure.
Dioxins are produced as unwanted by-products from combustion processes, including vehicle emissions, coal and wood fires in homes, barbecues, back-yard incinerators, disposal of plastic wrap from hay bales, and crematoria. Overall these are not huge contributors to the total atmospheric load and are beyond sensible control through the application of a standard, so action is not proposed for these sources.
The most recent major survey of dioxin emissions in this country gave by far the biggest source (39%) as fires in landfills. Most local authorities have since put controls on this, and regional councils agree with the proposed standard to ban such fires.
In other countries a major source of dioxin emission is metals refining, but in New Zealand metals refining accounts for less than 10% of national emissions.
Dioxins and a host of other toxic chemicals are associated with the following intermittent burning activities:
- burning of insulated copper wire to recover the copper
- burning tyres in the open (where there is no appropriate pollution control)
- burning road seal (bitumen burn-off), an out-dated practice for road maintenance
- burning oil in the open (where there is no appropriate pollution control)
- low-temperature incinerators in places such as schools and hospitals, which are insidious generators of dioxins in places where people are most vulnerable
- high-temperature incineration of hazardous waste.
The environmental and health effects of these activities, particularly in terms of dioxins emissions, have been discussed in several technical reports prepared by the Ministry for An Action Plan for Reducing Discharges of Dioxin to Air (Ministry for the Environment, 2001a). The Ministry considers that these studies justify the need to either completely stop these discharges, or restrict them to ensure they are carried out with appropriate control equipment. Typically, for the activities we are proposing to ban there are alternative, more environmentally friendly options that can be used to achieve the same purpose.
There has been a recent history of work towards a dioxin standard for New Zealand. This work shows that if a numerical standard were to be chosen for dioxins, the most defensible figure for either an emission standard or an ambient level is 0.1 nanograms of toxic equivalent per standardised cubic metre; or 1 part in 10,000,000,000,000 of a kilogram in a cubic metre of atmosphere.
The very low level of 0.1 nanograms per cubic metre could be measured only by special equipment in special circumstances, and it is a significant challenge to measure in most locations where the emissions are an issue. It would not be possible or practicable to take measurements of most point sources of interest. There would also need to be many exemptions (e.g. crematoria, barbecues). The Minister for the Environment proposes that a more effective and direct approach to standards for dioxins is banning those activities that are major or localised sources of dioxins and other toxic chemicals. This will deliver on the Government's policy to reduce dioxin discharges in the most efficient and effective way.
Low-temperature incinerators are significant generators of dioxins and other toxins. It is likely that all existing school incinerators, hospital incinerators, etc. would fail any reasonable test for part or all of their burning cycle. Action is required because of both the level of pollutants and the proximity of the incinerators to vulnerable members of our society. It is pointless to propose a dioxin emission limit or atmospheric standard for such incinerators, because they simply could not meet it. Instead, we offer open encouragement to the potential operators of school and hospital incinerators to avoid installing new ones. If they need to use incinerators, they will be required to obtain a resource consent by 2006. The rubbish burnt at these incinerators can be disposed of by other methods such as landfilling or steam sterilisation.
There is a significant history of concern about large-scale incinerators. Opponents of these incinerators rightly claim that there is no safe level for dioxins, and that even an extremely low atmospheric standard like 0.1 nanograms per cubic metre is not a guarantee of protection. They also claim that there are other issues of public concern with incinerator emissions, and that setting an atmospheric standard could inadvertently act as a proxy for a decision on acceptability. Finally, they claim that incinerators are becoming obsolete technology for hazardous wastes, and more environmentally friendly technology is used elsewhere. It would be very difficult today to justify a resource consent for a new high-temperature hazardous waste incinerator.
There are good reasons for New Zealand's emphasis (through the RMA) on the control of impacts rather than the control of activities. But this is not a case in point. As explained above, an atmospheric dioxin standard would be an ineffective and inefficient way to prevent concerns that could be better managed by direct decision-making. We therefore propose to ban new high-temperature incinerators built for the purpose of destroying hazardous waste.
Further justification for the proposed bans can be found in the section 32 documents prepared for the proposed Dioxin Action Plan (with the exception of hazardous waste incineration).
