Until the early 1970s, responses to air pollution were localised and limited. In Christchurch, for example, local councillors could do little to reduce the build-up of traffic fumes and household smoke beneath the inversion layer that formed a frequent umbrella over the city. Auckland also had problems with odours, traffic fumes and some industrial emissions. As public concern grew, the matter was finally taken up by central government and, in 1972, the Clean Air Act was passed.
The Clean Air Act regulated emissions of pollutants from industrial and trade processes, and classified pollution sources according to their type and rate of heat release. Major polluters were required to obtain licences from the Department of Health which were effective for anywhere between 1 and 5 years. For each licence, Health Department officers determined the 'Best Practicable Means' (BPM) of pollution control (Ministry for the Environment, 1994a). Under this BPM approach, large industrial sources of air pollution were instructed to operate in specific ways and to install particular control technologies to minimise emissions.
City and district councils were empowered to operate a similar licensing system for smaller air polluters. The controls imposed by these authorities were varied and were based on site-specific considerations and the Health Department's BPM guidelines. To deal with air pollution arising from dispersed sources (e.g. households), the Clean Air Act allowed local authorities to establish Clean Air Zones, in which emissions were controlled through by-laws rather than licenses. The only place ever declared a Clean Air Zone was Christchurch. The Christchurch City Council took the step to control the smoke pollution caused mainly by open fires. Within the Christchurch Clean Air Zone, grants were made available for homeowners to replace open fireplaces with approved non-polluting heating appliances, and restrictions were imposed on the types of fires which could be installed in new houses and on the types of coal and other fuels that could be burned in them.
One effect of the Clean Air Act was an upsurge in monitoring activity both regionally and at specific sites. However, this fell away in the late 1970s as emissions improved at some sites and as monitoring was considered unnecessary at others. Routine monitoring continued mainly in Auckland and Christchurch, the two centres with the greatest potential for problems. As a result of these monitoring programmes, we know that sulphur dioxide pollution and particulate matter decreased following the introduction of the Clean Air Act. However, this may have been coincidental rather than causal, with the Act merely spurring along a process of declining coal use that was being driven, in large part, by the aggressive promotion of electricity.
Another significant change in air quality occurred quite independently of the Clean Air Act. This was the progressive reduction of lead emissions from motor vehicles. It took place in a series of steps from 1986 to 1996 (see Box 6.7). Concern about lead in petrol had started to emerge in the 1970s as scientists overseas began connecting low level exposure to lead with developmental disorders in children. Leaded petrol, leaded paint, and lead-lined pipes and containers were identified as the main culprits, with petrol being the most widespread of these, and the hardest to avoid.
Both the Super grade (high octane) and Regular grade (lower octane) petrol on sale at the time contained high amounts of lead. New Zealand was slower than many other countries in responding to the concern about leaded petrol, but eventually measures were introduced and lead levels in air began to decline from the mid-1980s (see Figure 6.11). In the original data this effect could be detected by about October 1986, or three months after the first reduction in the lead content of Super petrol. The lag probably reflects the time taken to purge the petrol distribution system of the older high lead supplies. The reduction in air lead levels for mid-1987 compared to 1986 was around 40 percent.
In summary, although the Clean Air Act may have prevented some situations from getting worse, it cannot be credited with bringing about the main improvements in air quality which occurred during the 1970s and 1980s. It also proved to be inadequate to the task of reducing emissions from industrial and trade sources. The Best Practicable Means (BPM) approach, which was meant to strike a balance between the level of emission reduction and costs of control, offered few incentives for innovation. Air pollution was managed in a programme which did not include water and soil; there was little opportunity for the public to give its views and the BPM system did not require the evaluation of the effects of total emissions from several sources in a given area.
Lead was first added to petrol in the 1920s as a cheap and convenient method of boosting octane (which enhances fuel combustion) and reducing engine 'knock' (caused by faulty combustion). The General Motors research engineer who made the discovery, Thomas Midgley, went on from this triumph to develop a non-toxic, non-flammable alternative to ammonia as a refrigerant-chlorofluorocarbon or CFC (Taylor, 1988). Today, both of these substances are recognised as major pollutants. When leaded petrol is burnt in the engine of a car, 75 percent or more is emitted from the exhaust as particulate matter, both large particles which fall rapidly to the ground, and finer particles (PM10) which can stay airborne for considerable periods of time. The result is significant contamination of street dust and adjacent soil, and elevated levels of lead in the air near busy roads.
The first step towards removing lead from New Zealand's petrol was taken in 1984 when the Ministers of Health, Environment and Energy announced that the Government intended, in two years' time, to reduce the lead content of 96 octane 'Super' petrol and to follow this with the introduction of an unleaded 91 octane 'Regular' petrol. These changes had to await the completion of the Marsden Point oil refinery expansion. Until the changes were made, New Zealand had a higher level of lead in petrol than most OECD and other developed countries (0.84 grams per litre compared to 0.15 grams). This was more in line with the less developed Asian countries, and most of Africa, South America, and the Caribbean.
In July 1986 the lead content of Super (96 octane) petrol was reduced from 0.84 to 0.45 grams per litre. By world standards this was still high. Most of Europe, including Britain, had reduced to 0.15 grams per litre and the United States limit was just 0.026 grams per litre (Taylor, 1988). In January 1987, Regular petrol was replaced by Unleaded 91. Despite the name, it was not strictly 'unleaded'. Contamination by leaded petrol sometimes occurs in pipes and tankers, even though no lead is intentionally added. Allowing for this, the maximum permitted lead content of unleaded petrol has been 0.013 grams per litre since 1 January 1992. However, a Ministry of Commerce survey of service stations in 1992-93 found that actual contamination levels are much lower, ranging between nil and 0.003 grams per litre.
The switch to unleaded petrol was not an easy one (see Figure 6.13). Regular petrol had accounted for only about 7 percent of the total market. This fell to a mere 4 percent immediately after the change because many drivers feared that Unleaded 91 was unsuitable for their vehicles, an impression that the oil and motor industries did little to reverse. Following a $500,000 promotional campaign by the Ministry for the Environment, the market share quickly recovered to 7 percent but was slow to increase after that, even though 2025 percent of vehicles could run on the unleaded fuel (Taylor, 1988). Eventually, in 1991, a 'lead tax' of 8 cents per gram was imposed on Super petrol. This made the price about 5 cents higher than Unleaded. It also spurred a further 'voluntary' lowering of the lead in Super petrol to about 0.35 grams per litre. The 1992-93 Ministry of Commerce survey found that a number of samples even had even lower levels-less than 0.1 gram per litre.
The final step in the transition from leaded to unleaded petrol was taken in June 1995 when the Government announced that the New Zealand petrol market would become lead-free. In January 1996 it became illegal to add lead to petrol and in September it became illegal to sell leaded petrol. A new higher octane petrol, Super Unleaded 96, was introduced but immediately ran into controversy when it was accused of causing fuel system leaks, engine fires and performance problems in some cars. In all, oil companies received several thousand complaints in the five months from March to July 1996. Of these, 2,636 complaints were investigated for possible compensation payment, among them 94 involving engine fires, and 1,213 involving fuel system problems (Ministry of Commerce, 1996).
One aspect of the controversy that has implications for air quality was the revelation that the new fuel has elevated levels of aromatic hydrocarbons (e.g. benzene). Aromatics in petrol do the same job as lead-they boost the octane rating. One imported batch of the new unleaded petrol contained a particularly high level of aromatics (56 percent), particularly toluene (54 percent). At the time a maximum benzene level of 5 percent by volume was permitted in all petrol. After the controversy, the Government introduced regulations which were based on a voluntary industry standard to control the levels of aromatics. These set a maximum specification for total aromatic content of 50 percent by volume from 20 March 1996, and 48 percent from 18 April 1996. The 5 percent maximum content of benzene remains unchanged. The net effect of the switch to lead-free petrol has been the virtual elimination of airborne lead from our environment, and a slight increase in emissions of benzene and other aromatics of about 1 percent (M. Bates, 1996).
The proportion of unleaded petrol sold in New Zealand increased since its introduction in 1989, while leaded petrol sales dropped. Since 1993 they have had similar sales levels. Overall, petrol sales have increased from around 1.5 million tonnes in 1985 to around 2 million tonnes in 1995. Since 1990 the average level of lead in petrol has been below the maximum permissible level, reaching about half the level allowable in 1993.
Source: Ministry of Commerce (1996)
The Clean Air Act was repealed when the Resource Management Act (RMA) took effect in 1991. In promoting the sustainable management of natural and physical resources, the Resource Management Act seeks to safeguard the life-supporting capacity of air, water, soil and ecosystems, and to avoid, remedy, or mitigate any adverse effects of activities on the environment. Under the new Act, the management of air pollution from all sources is the responsibility of regional councils and unitary authorities.
The Act does not set air quality standards or pollution thresholds, but leaves that for each authority to determine. However, the Act does require the Ministry for the Environment to provide guidance to councils including, where necessary, either binding standards or non-binding guidelines. Given the variable conditions around the country, the Ministry has opted to issue guidelines (Ministry for the Environment, 1994a). These show 'safe' levels for human health of the most commonly known and widespread air pollutants (see Table 6.3). The guidelines are based largely on the World Health Organisation (WHO) Guidelines for Europe, supplemented by more recent information from the United States Environmental Protection Agency (EPA) and the Victoria (Australia) EPA.
Because they do not take into account the effects of air pollution on visibility, sensitive species (e.g. lichens), or corrodible structures such as monuments and historic buildings, they are not environmental guidelines in the true sense. However, regional councils may set more stringent air quality thresholds if they choose, having regard to their responsibility under the Resource Management Act to consider ecological, cultural, and intrinsic values in the environment. Research to assess which levels of air pollution are ecologically or culturally tolerable has not, to date, been a priority in New Zealand.
Apart from assisting with guidelines, the Ministry for the Environment has also been collaborating with regional councils and the National Institute of Water and Atmospheric Research (NIWA) to coordinate the development of indicators for air monitoring. These include a national set of core indicators to be monitored routinely at a selection of urban and rural sites. Among the recommended priority indicators are: carbon monoxide (CO); inhalable particulates (PM10); nitrogen dioxide (NO2 ); sulphur dioxide (SO2); ozone (O3); and a measure of visibility (Fisher and McMillan, 1996).
Under the Resource Management Act, regional councils can set down statutory plans with air quality standards that must not be breached. These standards must take into account all pollution sources, both large and small. Whether a council has developed a plan or not, large emitters, such as factories, are controlled through air discharge permits, in which the council specifies the maximum amount of a particular pollutant that may be discharged over a given period. These permits do not dictate which particular equipment must be used to control emissions, leaving that decision to the manager of the installation. However, if emissions exceed the permitted levels, the polluter may be closed down.
Small emitters, such as motor vehicles and households, cannot be so easily managed through a permit system. Other measures are needed to control air pollution caused by them. These may include changing traffic flows, improving access to public transport, encouraging the adoption of cleaner forms of home heating and better insulation, encouraging drivers to install catalytic converters, or simply encouraging them to have their vehicles regularly checked and tuned.
This last option was tried in Christchurch from late 1993 to mid 1996 when the Canterbury Regional Council set up the country's first free vehicle emission testing programme. It found that 44 percent of vehicles tested were poorly tuned and emitting high levels of pollutants. However, just as other councils, such as Environment Waikato and Waitakere City, were establishing similar programmes in 1996, the Christchurch programme was discontinued because it did not appear to have actually reduced emissions (Lusby, 1996; Ayrey, 1996; McChesney, 1996).
Emissions monitoring is still very undeveloped in New Zealand, though this is changing. The Ministry of Transport has undertaken several studies of vehicle emissions. These include: the Land Transport Pricing Study, which attempts to cost the environmental impacts of transport; the Vehicle Fleet Strategy, and the Vehicle Emission Testing Study. Home heating emissions have recently begun to be studied by the Canterbury Regional Council.
In October 1995, the Ministry for the Environment's Sustainable Management Fund approved a large three-year research project to provide guidance for regional councils on the elements of air quality management. During the first phase of the project, the National Institute of Water and Atmospheric Research ran a series of workshops in 1996 which brought together air quality professionals from central government, regional authorities, and the Crown Research Institutes. The project's other elements include several air monitoring surveys and the development of a prototype national air quality database.
|Contaminant||Acceptable Average Level||Averaging Period|
|Particulates (PM10)||120 µg/m3||24-hour|
|Sulphur dioxide (SO2)||500 µg/m3||10-minute|
|Carbon monoxide (CO)||30 mg/m3||1-hour|
|Nitrogen dioxide (NO2)||300 µg/m3||1-hour|
|Fluoride: Special land use||1.8 µg/m3||12-hour|
|General land use||3.7 µg/m3||12-hour|
|Hydrogen sulphide (H2S)||7 µg/m3||30-minute|
µg - micrograms
mg - milligrams
AS - Australian Standard
Source: Ministry for the Environment (1994)
Strategies will be developed for assessing visibility and for managing air toxics (with the main focus on motor vehicles and agricultural chemical sprays). The project will also develop guidance manuals on how to use computer programmes which model the dispersion of contaminants in the atmosphere, including what models to use in what situations and how to create local meteorological datasets to put into the models. Guidance manuals are also being prepared on how to develop emission inventories and record compliance monitoring information.
Several regional councils have begun to develop regional air plans which identify their issues, objectives, policies and methods for managing air quality. This process has been difficult however, due to lack of air quality information. Most of the plans set out the programme the council will follow to gather data to improve councils' ability to sustainably manage air quality. Canterbury Regional Council appears to be most advanced in its air quality programme having studied household heating and vehicle emissions and recently introduced tougher emission standards for new woodburners. Council officers are also working on plans for the gradual phasing out of open fires and older woodburners.