In October 2001 the European Commission published its new transport policy document with the sub-title “Time to Decide”. Clearly the Commission has already decided that transport conditions in Europe for over 300 million citizens are rather poor now and are set to deteriorate even further by the 2010 which is the time horizon of the transport policy document. Sadly the Commission has set the whole transport policy debate within a very unimaginative context of some modest modal shift (less use of road and more use of rail) and some suggestions for charging lorries for their use of road space. This misses the opportunities of fundamental demand management strategies. The Commission finds it very difficult to grasp the concept of traffic reduction. We can reduce the numbers of cars on the streets by land use planning and demand management. We can reduce the number of lorries (and the distances they travel) by innovative spatial/regional organisational strategies designed to increase the proportion of local products consumed locally and we can reduce the explosive increase in demand for flying by making sure that the cost flying to the passenger “tells the ecological truth” and that airports respect elementary public health controls. All this has been missed by the Commission and their White Paper now sets us very firmly on a “business as usual” trajectory with just a little bit of hand waving and concession to the “green lobby”. The European Commission has decided to do a lot more of the same thing over the next 10 years.
The consequences of pursuing a business as usual strategy are very clear:
· increasing levels of congestion on Europe’s motorways and urban roads. Congestion costs alone in the EU are expected to equal 80 billion Euros pa
· significant increases in greenhouse gases from transport. Transport’s production of GHG will make the achievement of EU reduction targets very difficult to achieve
· significant health impacts from lack of physical exercise, noise, respiratory disease and road traffic accidents
· significant damage to neighbourhoods, community and liveability as traffic levels damage social interaction and public use of streets
· significant costs in futile attempts to cope with the steep increase in transport demand. The UK 10 year transport plan calls for £180 billion (UK sterling) investment in physical infrastructure
· more polarised societies as wealthier groups travel more (air, high speed train and car), poorer groups travel less and the environmental impacts of travel on the part of the wealthy bear down disproportionately on the poorer groups.
· Spatial changes in European society so that urban sprawl accelerates, cities lose their cultural and economic significance and move in the direction of “doughnut cities”. Agricultural, nature protection and recreational land is lost and travel distances increase
The White Paper has described the main elements of the transport problem. Most passenger and goods traffic goes by road. In 1998 road transport accounted for nearly half of goods traffic (44%) and 79% of passenger traffic. The road share of freight transport is much higher than the 49% figure if we look at land transport. In the UK, for example, road freight carries 70% of all freight tonne kms. The figure comes down on a European scale because of the importance of coastal shipping and freight on the inland waterways (especially the Rhine and the Danube).
In the period 1970-2000 the number of cars in the EU trebled from 62.5 million to nearly 175 million. Overall car travel (car-km) is growing at about 3% pa. The number of cars is rising by 3 million every year and the enlargement plans of the EU which over the next 10 years will bring Poland, Hungary and Romania (and others) into the Union will add to this total. The so-called accession countries in common with many other ex-Soviet bloc countries (Baltic states, Slovakia, Czech Republic) are all experiencing car ownership and use growth rates that are much larger than the current EU average. These growth rate are encouraged by the EU through its funding mechanisms for encouraging motorway construction (eg the motorway around Budapest) and pursuing grandiose plans for long distance motorway connections (Trans European Networks).
Road haulage is set to grow by about 50% by 2010. In the period 1970-2000 it grew at about 5% pa. Changes in European manufacturing organisation, logistics and sourcing strategies are all adding to the burden of road freight. Road freight grows as a result of the organisational decisions of production companies and logistics operations and not because of the growth in the demand for physical products. The distances over which goods move every year grows by around 6% and the decisions of manufacturers to move those goods over thousands of kilometres (because transport is too cheap) fuels the demand for new motorways, new Alpine crossings and new crossings between France and Spain (Pyrennees). The European Union is determined to assist in this process of energy intensive, distance intensive production development which is why there is so much emphasis in the White Paper on very expensive new infrastructure to connect Germany and Denmark with a fixed link (Fehman crossing). The cost of the EU’s planned major infrastructure links is a staggering 1800 billion Euros and much of this capacity will simply move products around from region to region when they are available in all regions anyway. This has been dubbed “useless transport” (Whitelegg, 1996).
The growth in demand for aviation is at an even faster rate than for car travel or road freight. Passenger kms flown are growing in Europe by about 8% pa and the very exceptional and tragic circumstances of September 11th are very unlikely to damage the medium-long term growth potential of the aviation industry. Indeed in late November 2001 the UK government gave approval for the construction of Heathrow Terminal 5 which at 30 million passengers pa capacity is bigger than Frankfurt Airport and will mean that Heathrow can handle 100 million ppa by 2010-2015. This decision is at the request of the aviation industry and is matched by similar decisions to build new airport capacity including yet another completely new airport for Paris. The aviation industry is clearly very confident about future success even though it is currently taking advantage of the unique circumstances surrounding international terrorism and is making staff redundant and reducing flights. This will increase the amount of public subsidy (£40 million was given to the aviation industry by the UK government in December 2001) and restore the usual trajectory which in the UK will require a new airport equal in size to Heathrow Airport somewhere in the country every 10 years.
The European Commission having expressed concern about greenhouse gases, congestion, land take and other consequences of the growth in demand for transport then goes on to say that the growth of aviation is “inevitable”:
“This reorganisation of Europe’s sky must be accompanied by a policy to ensure that the inevitable expansion of airport capacity linked, in particular, with enlargement remains strictly subject to new regulations to reduce noise and pollution from aircraft” (p14).
This is the clearest expression of the Commission's fundamental lack of understanding of sustainable development and transport. There is nothing inevitable about the growth in demand for transport, including growth in demand for aviation. I shall return to this subject in a later section of this chapter.
Greenhouse Gases CO2 emissions from transport in the EU increased by 47% between 1985 and 2001. Other sectors increased by 4.2%. More than 30% of final energy in the EU is now consumed by transport If this trend continues the EU will not meet its Kyoto commitments.
Road transport is the main cause of this increase and contributed 84% of the CO2 emissions from transport in 1998. CO2 emissions from road freight are also expected to rise substantially, by 33% between 1990 and 2010. Road transport is also a small but growing source of nitrous oxide (N2O) emissions from passenger car catalysts. Emissions doubled between 1990 and 1998 to 7% of total N2O emissions.
In 1998 EU greenhouse gas emissions from international transport (aviation and shipping) amounted to 5% of total EU emissions. Aviation emissions are expected to rise dramatically in future years (Whitelegg, 2000) and to account for about 15% of greenhouse gas emissions from the transport sector by the year 2020.
Attempts to restrict or reduce GHG from transport in Europe have largely failed. A voluntary agreement with the automobile industry to set an emission limit of 140g/km of CO2 will reduce the rate of growth by a few percentage points but is more than compensated for by the increase in popularity of sports utility vehicles (SUVs). SUVs are very large, heavy, 4 wheel drive, jeep like vehicles with very poor fuel efficiency and very high GHG emissions (>250g/km). Their market penetration is very high in the US and in Europe. Average vehicle occupancy is falling as more people choose to travel alone in their vehicles so increasing per capita GHG and cancelling out fuel efficiency gains.
Put very crudely European car transport is characterised by increasingly fewer persons in increasingly heavier and more polluting vehicles. This is not a trend that can be influenced by technology.
Urban sprawl and logistic tendencies also exercise a powerful influence on GHG. The UK has seen a substantial increase in car use for retailing as retailing has moved towards the US style “mall” concept. Large shopping centres on edge of city sites (eg Meadowhall in Sheffield, Metro Centre in Newcastle and Trafford Centre in Manchester) have all proceeded on the basis of attracting shoppers from distances of over 100km to their thousands of car parking places. The impact on traditional retailing centres has been very negative eg on Dudley near Meadowhall which has lost about 40% of its retail space and shopping trips account for more miles travelled than commute trips. Other European countries have resisted these trends. In Denmark shopping is still conducted in traditional city centre retail outlets supported by local residents. Germany has also resisted these trends but the accession states (Hungary, Poland etc) are moving very fast in the direction of the out of town centre. Urban sprawl has the potential to counteract and over-compensate for any technological gains made in fuel/engine efficiency and also any gains made by fiscal means (eg fuel taxation, congestion charging, car park charges). Without a radical change in the business/developer driven agenda towards business parks, shopping malls and new models of suburbia Europe will not meet Kyoto targets and will see a continuing growth in transport GHG emissions.
The European Environment Agency in Copenhagen has addressed this issue and predicted (EEA, 2001) that GHG emissions from transport will be 39% above the 1990 levels by 2010. This does not include the aviation GHG emissions which can be allocated to EU citizens on the basis of their air miles and are currently not counted in EU GHG inventories.
Road freight transport is a particular source of concern in the EU. Road freight tonne kms increased by 29% in the period 1990-1997 and road freight could increase by much more in the future. The road freight problem is essentially one of the spatial organisation of production and logistic supply chains. Paradoxically because logistics is so well organised and so sophisticated (just in time, very short lead times, satellite tracking, reliability) it is now possible in Europe at very low costs to source a huge variety of raw material and semi processed inputs into a production chain that is very widely dispersed. Essentially the traditional barriers of the friction of distance and the cost of movement have been removed. It is now normal to move thousands of products over tens of thousands of kms in a highly efficient manner. The products will be delivered exactly where they are needed at the time they are needed. One of the best documented examples of this process is the case of the yoghurt pot (Boege, 1995). Boege made a study of yoghurt production at one factory in Stuttgart (Germany) and found that many different products and sub products went into making the final consumer product. The final product was so transport intensive that it was possible to calculate that each 150g pot of yoghurt was responsible for moving one lorry 9.2 metres. Similar trends can be observed throughout food retailing (onions from Poland) and globally (onions on sale in UK supermarkets from New Zealand). Furniture and household products sold by IKEA throughout the EU are made up of parts sourced in eastern Europe (eg Poland), assembled at various place in Europe, shipped to Sweden, shipped to the UK and so on. The distance intensity of such production processes is increasing at an increasing rate and produces more GHG.
The Health Impact of Transport
It is only very recently that the full extent of transport’s negative impact on health has become clearer. In an ecological audit of the impact of cars on German society Teufel et al (1999) concluded that cars were responsible for 47,000 deaths each year and a range of other, less severe, health impacts. These are summarised in Table 1.
Table 1 Health damage caused by cars, Germany, 1996, annual totals
deaths from particulate pollution
The volume of death and illness revealed in Table 1 puts the European transport problem into a very serious public health perspective. Transport is a major health problem and should be tackled as much within a public health context as in a traditional transport/roads/highway context. All the deaths and injuries in Table 1 relate to cars and not to lorries or aircraft. Total deaths are about 5 times greater than road traffic accidents deaths.
The total amount of sickness, days in hospital etc imposes a huge burden on the health services of European countries and this burden is not recovered from those who drive cars. The health impact is a huge human tragedy. 15 million days of use of bronchodilators is a huge problem for many children and many families and the impact on physical activity, social activity, enjoyment of outdoor pursuits, community and neighbourhood is incalculable. Health impacts in Europe in the 21st century are the direct equivalent of disease impacts in 19th century cities which then required major re-engineering with clean drinking water and sewage systems. We are still waiting for the 21st century equivalent of this re-engineering to deal with the modern equivalent of widely dispersed sewage.
Road traffic noise and noise from aircraft also create significant health problems (WHO, 1996). These health problems are generally understated in Europe with an implicit assumption on the part of traffic engineers and planners that most people can get used to noise and, in any case, it is only a minor irritation and part of life in an advanced industrial society. This has to be rejected. Noise causes raised blood pressure, cardiovascular disease, a range of psychological problems, sleep disturbance and it damages school age children if they are exposed to noise in a learning environment. WHO (1993) discusses the evidence that supports the contention that children exposed to noise learn less well and have reading abilities lower than is the case for children not in noisy environments. Studies around Heathrow Airport in SE England also point to damage to children living near the airport and under flight paths.
Children suffer in other ways as a result of the growth in car use and mobility. It is common in the UK though less so in Germany, Denmark and the Netherlands for children to be taken to school by car. Hillman, Adams and Whitelegg (1992) drew attention to the serious impact of this tendency especially in the loss of independent mobility on the part of young children. The consequences of this loss of independence and physical activity are that the UK has the highest rate of over weight and obesity amongst its 15 and 16 year olds in the European Union (NAO, 2001). Children (and young adults) increasingly living a sedentary lifestyle with very little physical activity incur a health penalty. As they grow into full adulthood they are more likely to experience cardiovascular problems and specific illnesses such as diabetes. A National Audit Office investigation in Britain (NAO, 2001) has identified the importance of walking and cycling as an important mechanism for reducing illness, reducing demands on the National Health Service and reducing the size of the growing bill for health care.
Traffic also damages community life and it is surprising that the frequently articulated comments of urban residents in European cities about the damage to neighbourhoods, community, social interaction and “liveability” are so poorly researched and understood. In European transport we know far more about the skid resistance of different road surface materials than we do about how traffic deeply affects psychological and physical well being in urban communities. The outstanding exception to this general rule is Donald Appleyard’s work in San Francisco (Appleyard, 1981). Appleyard shows in a series of diagrams that heavily trafficked streets seriously impede social interaction to the extent that residents on these streets have much less social contact and fewer friends and acquaintances than do residents on lightly trafficked streets. This is not just a passing item of sociological interest. Isolation is keenly felt by elderly people and by parents with young children. Poor physical conditions reduce the attractiveness of urban living and contribute to economic decline, outmigration and the downward spiral of urban decay. Low levels of physical use of public space (few people actually walking) increase the likelihood of crimes against the person and burglary. Cities are attractive when they are well used by people and cyclists (as is the case in Copenhagen) or very well “policed” in the sense that there is a significant degree of general public surveillance as is the case with German and Austrian tram systems. Travelling by tram through Dortmund or Bochum in Germany or Vienna (Austria) provide ample opportunities for everyone to survey and “oversee” everyone else. The significant public presence is qualitatively and quantitatively different from that provided by car users who are in a very private and insulated world.
Studies of individual exposure to pollution (Rank, Folke and Jesperson, 2001) show that car occupants are exposed to 2-4 times as much pollution from vehicles as are cyclists. This finding is in some ways counter-intuitive and surprising but is the result of cars following a very similar path through traffic to that followed by all other cars and effectively driving in a “tunnel of pollution”. This raises the very interesting and important conclusion that the car itself damages the health of car occupants. The conventional view is that cars are safer and more pleasant than cycling (presumed to be a dangerous activity). Scientific research shows that this is not the case and the growth of car use in Europe (especially the increase in the number of children carried around by car) represents a significant public health problem which is at least an example of direct correspondence between perpetrator and victim. Those that cause the problem suffer the consequences of that problem.
In October 2001 a group of residents living in the vicinity of London Heathrow Airport won a court action before the European Court of Human Rights in Strasbourg. The Court ruled that they had been deprived of their human rights because they could not have a good night's sleep. The Court also ruled that the UK government had denied the residents an adequate remedy for their complaint and, further, that the UK government had not demonstrated that there was an overriding economic reason why night flights had to take place. This ruling is very significant indeed. It establishes a link between transport impacts and human rights that is of wider significance than airports. Local residents in Austria, Italy and France have equally serious problems living in the vicinity of major trans-Alpine motorways. It widens the transport debate far beyond the boundaries of traditional studies of noise and air pollution and it demonstrates the importance of fundamental traffic reduction strategies. Many transport problems cannot be solved by technology or tinkering around the edges. In a crowded continent like Europe transport problems require fundamental solutions that produce reduced levels of demand.
Flying is in many ways the ultimate expression of the energy intensive, distance intensive life style that has come to dominate the developed world. It is also one of the most heavily subsidised modes of transport (there is no taxation on aviation fuel) and a mode that has unique levels of access to the highest levels of government and to government support of airport expansion, new road and rail infrastructure and very soft loans from European agencies (eg the European Investment Bank). Aviation is also a very polluting activity and a significant source of greenhouse gases. It is an unsustainable mode of transport.
Ground level air emissions
Aviation is responsible for a number of damaging environmental and health effects. These are growing in significance in Europe and are likley to continue to grow as globalisation trends intensify and eastern European countries move towards EU levels of flying (freight and passenger). Noise is a well documented and damaging consequence of living near airports or under flightpaths. Less well known are the air pollution consequences of airport and aircraft activity.
US research (Natural Resources Defense Council, 1996) shows that air pollution from cars and industry has declined with time while aircraft continue to emit more ground level ozone precursors (Volatile Organic Compounds or VOCs and nitrogen oxides or NOx) with each passing year. Airports in the US are in the top four largest emitters of NOx and VOCs (depending on location), together with power plants, the chemical industry and oil refineries. These data are not readily available in the UK where published information (eg Environment Agency) does not list airports. Airports are also significant traffic generators, freight distribution centres, taxi destinations and bus stations and are responsible for significant amounts of pollution from the exhaust emissions of land based transport. They also have large amounts of fixed and mobile generating equipment to supply aircraft with power whilst they are on the stand and large scale maintenance facilities for engines and aircraft. They are also large fuel depots with storage tanks, fuel lines and refuelling facilities all contributing evaporative emissions of VOCs to atmosphere.
Evidence presented at the public inquiry into Terminal 5 (T5) showed that NOx levels would be 110% higher in 2016 (with T5) compared with 1991 and 45% higher in 2016 (without T5) compared with the same base year. This is a very significant increase (from an already high base line) in a pollutant which is directly associated with smog formation and with damaging human health impacts. The other pollutants (VOCs, CO and SO2) also show increases even without T5.
The scale of the emissions from Heathrow Airport can be evaluated by reference to Environment Agency data on local pollution. They are presented in the form of regional rankings of polluting factories and rankings of polluting factories by chemical released to atmosphere. In the case of VOCs Heathrow with Terminal 5 (in the year 2016) is predicted to produce 2052 tonnes of VOCs (the 1991 total for VOCs was 2224 tonnes and the reduction is due to predicted improvements in vehicle emissions). This would make it the second largest polluter for this chemical in England and Wales, after BASF on Teesside (north east England). Heathrow contributes about 10% of the England and Wales total of VOCs and yet does not figure in the Environment Agency list of point sources and is not controlled on a site basis. Airports in the UK are specifically excluded from the provisions of Integrated Pollution Control.
US data show that Kennedy Airport is the largest source of NOx in New York and the second largest source of VOCs. Both these chemicals combine to form ground level ozone which in its turn damages the respiratory system of humans and causes breathing difficulties, increased mortality and increased hospital admissions. Scientific studies reported in Natural Resources Defense Council (1996) report that exposure to ozone at "relatively low" levels significantly reduces lung function and induces respiratory inflammation in healthy people during moderate exercise. Chest pain, coughing, nausea and pulmonary congestion often accompany this decrease in lung function. Other studies cited show that "repeated exposure to ozone for months to years can produce permanent structural damage in the lungs and accelerate the rate of lung function decline. NOx also contributes to particulate matter which in the US produces 64,000 premature deaths every year".
VOC emissions include a number of toxic pollutants which in addition to their role in ozone formation at ground level have a direct impact on human health. These include formaldehyde, benzene and 1,3 butadiene. A 1993 study carried out by the US Environmental Protection Agency (EPA) concluded that these pollutants contributed to elevated rates of cancer incidence in the vicinity of Midway Airport (SW Chicago). Midway's arriving and departing planes contribute far more of these toxic pollutants than other industrial sources within a pre-defined 16 square mile study area. The EPA study estimates that aircraft engines are responsible for 10.5% of the cancer cases in SW Chicago caused by toxic air pollution. There are no studies of cancer incidence and toxic pollution around UK airports, several of which are much larger than Midway.
The impact of these pollutants on human health can be summarised as follows:
Carbon Monoxide (CO): at high levels it causes headaches, drowsiness, nausea, slowed reflexes and at very high levels, death. At low levels it can impair concentration and nervous system function and may cause exercise-related heart pain in people with coronary heart disease
Nitrogen Oxides (NOx): impair respiratory cell function and damage blood capillaries and cells of the immune system. They may increase susceptibility to infection and aggravate asthma, In children exposure may result in coughs, colds, phlegm, shortness of breath, chronic wheezing and respiratory diseases including bronchitis.
Ozone: ground level ozone reduces lung function in healthy people as well as those with asthma. It may increase susceptibility to infection and responsiveness to allergens such as pollens and house dust mites. It may cause coughs, eye, nose and throat irritation, headaches, nausea, chest pain and loss of lung efficiency and increases in the likelihood of asthma attacks.
Particulate matter (PM): strongly associated with a wide range of symptoms such as coughs, colds, phlegm, sinusitis, shortness of breath, chronic wheezing, chest pain, asthma, bronchitis, emphysema and loss of lung efficiency. As many as 15% of asthma and 7% of Chronic Obstructive Pulmonary Disease cases in the urban population are estimated to be possibly related to prolonged exposure to high concentrations of PM. Long term exposure is associated with increased risk of death from heart and lung diseases. PM may carry carcinogens such as polycyclic aromatic hydrocarbons (PAHs), hence may increase the risk of developing cancer.
Volatile Organic Compounds (VOC): This category of pollutant includes thousands of different chemicals many of which are hydrocarbons (HC). They may cause skin irritation and breathing difficulties; long term exposure may impair lung function. Many individual compounds are carcinogenic (including benzene). Benzene can cause leukaemia. Those most at risk are people exposed to benzene at work or who live or work in the vicinity of petrol filling stations or general vehicle activity.
Sulphur Dioxide (SO2): SO2 irritates the lungs and is associated with chronic bronchitis. People with asthma are particularly vulnerable and a few minute's exposure to the pollutant may trigger an attack. However the most serious effect occurs when SO2 is absorbed by particulate matter which is then inhaled deep into the lungs. At high doses it can release sulphuric acid on reaction with moisture in the lungs. This can result in widespread death and illness, for example, it is likely to have been the main cause of the 4000 deaths during the notorious 1952 London smog.
Source: British Lung Foundation (1998) Transport and Pollution: the health costs
The official view of the UK government expressed in its evidence to the T5 inquiry is that aviation contributes very little to local air pollution. The US data quoted above clearly contradicts this view and local inventories of emissions around Zurich Airport and Stockholm Arlanda Airport show that aviation contributes a significant share of total emissions within a well-defined geographical area. The information for Zurich and Stockholm is available because both these airports are capped in terms of the pollutants they can produce. The Zurich data is presented below in Table 2.
Table 2 Zurich Airport: emissions to atmosphere (t=tonnes)
Airport Regional Perimeter Canton of Zurich
Contribution of airport
Airport regional perimeter is defined as an area 9x12 kms around the airport
The Canton of Zurich is taken to mean the area covered by the internationally defined landing and take off or LTO cycle
Source: Airports and the Environment edited by Anne Paylor, MDIS Publications Ltd, Chichester, West Sussex, 1994
A report on Frankfurt Airport (Rhein-Main-Flughafens Frankfurt/Main) and its environmental impact compared the airport's contribution to total NOx, unburnt hydrocarbon, carbon monoxide and sulphur dioxide emissions in the Frankfurt area. The results are shown in Table 3.
Table 3 Frankfurt Airport's percentage contribution to total pollution in the Frankfurt area
NB the data are from 1979
Source: Konzepte Studie zur Umweltsituation des Rhein-Main-Flugahafens Frankfurt/Main, TUV Rheinland Gruppe, 1992
The Heathrow Terminal 5 Public Inquiry produced similar data from the evidence presented by the British Airports Authority (BAA). Table 4 summarises this information.
Table 4 Percentage Contribution of Heathrow Airport to annual emissions of four pollutants in the near Heathrow region
2016 5T 100mppa
NB The near Heathrow region is an area 8kmx6km centred on the airport, an area close to but excluding the airport
4T= four terminals (the present number)
5T=five terminals (the decision on the 5th terminal is still awaited)
Source: evidence presented by Tabitha Stebbings on behalf of the Local Authorities opposed to T5 (LAHT5) at the public inquiry
Emissions are not the same thing as air quality around airports. The evidence on air pollution around major European airports is very clear indeed. Airports are significant contributors to air pollution and to elevated levels of particulate pollutants that are known to cause damage to human health. The London Borough of Hounslow which borders on Heathrow Airport and is responsible for air pollution monitoring is of the view that "further expansion of the airport and associated road traffic congestion could lead to significant worsening of local air quality (Source: www.hounslow.gov.uk/es/monitor.html). In a press release dated 10.8.99 the same London Borough concludes "It is clear that the use of motor vehicles and the operation of Heathrow Airport heavily influence the levels of air pollution in Hounslow". Pease (1999) describes the situation around Gatwick:
"The Gatwick Study reveals a dramatic rise in aircraft derived emissions-particularly NOx. For this pollutant at least, it will mean that air quality in neighbouring Horley will remain above National Air Quality Strategy levels beyond 2005 despite the dramatic drop in road vehicle emissions….particulate pollution is high in and around Gatwick. It reaches 85mg/m3 at the centre of the airport and exceeds the 50mg/m3 guidance level for many miles beyond".