4 Population and Human Health
4.1 Environmental Objectives
4.1.1 Many existing environmental protection objectives are relevant to population and human health, either directly or indirectly. For example, the Air Quality Standards (Scotland) Regulations 2010  , the Air Quality (Scotland) Regulations 2000, the Air Quality (Scotland) Amendment Regulations 2002 and the Air Quality (Scotland) Amendment Regulations 2016  help set out current objectives and requirements for air quality with clear relevance for human health.
4.1.2 Protection is also afforded through existing legislation against noise and vibration nuisance at both the European level through the Environmental Noise Directive (2002/49/ EC)  and the national level through regulations such as the Environmental Noise (Scotland) Regulations 2006  .
4.2 Environmental Context
4.2.1 Air quality is important for both short and long-term human health, and poor air quality can have impacts on people with existing health issues. In general, healthy people may not suffer from any serious health effects from exposure to the levels of pollution commonly experienced in urban environments. However, continual exposure can cause harm over the long-term, and those with pre-existing health conditions such as heart disease, lung conditions and asthma can be adversely impacted by daily exposure to air pollutants  . Activities that generate air pollutants have been considered under the topic of Air Quality.
4.2.2 Noise has historically been the principal environmental issue for aviation and remains high on the agenda of public concern  . The European Environmental Noise Directive (2002/49/ EC) defines environmental noise as harmful or unwanted outdoor sound created by humans, including noise emitted by transport and air traffic  . Aviation noise generates considerable interest as it tends to cover larger geographical areas and is more difficult to mitigate when compared to road and rail noise  .
4.2.3 Aircraft noise is generated by both the engine and the airframe and is most evident during landing and take-off, with further noise generated from taxiing aircrafts, the application of reverse-thrust during landing, engine tests and airport vehicular traffic. However, noise impacts can also extend to vehicular and rail traffic to and from the airport, alongside noise disturbance associated with construction activities associated with infrastructure development.
4.2.4 The effects of disturbance, particularly increases in noise and nocturnal noise is a complex area of study and the potential impacts on human health can be varied and wide ranging. It has been reported that noise can cause sleep disturbance, fatigue and annoyance. Annoyance can also be accompanied by stress-related symptoms leading to changes in heart rate and blood pressure  . This linkage between noise disturbance and stress has been demonstrated by a range of noise impact studies, alongside additional effects such as losses of concentration and anxiety  . However, information on the relationship between noise exposures and their potential adverse effects upon people is also of variable quality  .
4.2.5 It is considered that airports in more densely populated areas will have a greater noise impact as more people are likely to be affected  . The phrase community annoyance has been suggested as the most useful catch-all term to describe overall, long-term aircraft noise impact, which can also be correlated with long-term average noise exposure  .
4.2.6 Whilst there could be some correlation between increased volume of traffic in and around airports and risk of collision and traffic accidents, it is difficult to identify with any certainty the likelihood and scale of risk. There are several factors that would influence this risk, such as modal competition, road design, speed restrictions and driver skill. This SEA cannot assess this potential secondary effect with appropriate certainty but it is considered unlikely that effects would be nationally significant.
4.2.7 The Scottish Index of Multiple Deprivation (" SIMD") ranks small areas (called datazones)  from the most deprived to the least deprived. It analyses data from a number of indicators across the domains of income, employment, health, education, skills and training, housing, geographic access and crime. Key findings from the 2016 Index show that 14 areas have been consistently among the 5% most deprived in Scotland since the 2004 Index  . The quality of the environment in which we live can greatly affect quality of life. Vulnerable populations can also be more susceptible and less resilient to health issues.
4.3 Assessment Findings
What are the likely implications of increased passenger and flight numbers on local air quality and noise exposure?
4.3.1 Air pollutants are emitted throughout flight activity. Depending on the stage of the flight or atmospheric level at which they are emitted, these can have implications for local level air quality. Furthermore, changes in local air quality levels may arise from increased passenger and flight numbers, potentially leading to increased road traffic to and from the airports. These are considered to be secondary impacts and have been based on the assumptions that the implementation of the policy will lead to increased passenger and flight numbers. However, it is considered that any secondary impacts that arise are outwith the ability of the policy option to influence.
4.3.2 Air quality issues currently exist in and around Scotland's airports. For example, there have been several Air Quality Management Areas declared along popular traffic routes to and from several airports  . The SEA of NPF3 noted that there could be mixed effects on air quality in relation to the proposed Strategic Airport Enhancements  . The assessment reported the potential for negative effects on air quality to arise as a result of increased levels of traffic to and from airports, in addition to increased flight numbers. However, potential benefits on air quality due to increased public transport connectivity were also reported.
4.3.3 Noise arising from operational activities can be a concern for people who live near airports, and aviation noise negatively affects more people in the UK than in other country in Europe  .
4.3.4 It has been assumed that an increase in passenger and flight numbers will occur as a result of the preferred policy option and consideration has been given to the following illustrative scenarios (as set out in paragraph 2.8.3). These are the likely impact on passenger numbers of applying a zero tax charge to only short-haul flights, with the tax charged on long haul flights maintained at current UK APD levels, and vice versa. It is considered that applying a zero tax rate amount to only short-haul flights could lead to higher passenger numbers than reducing both short-haul and long-haul flights by an equal proportion or applying a zero tax rate amount to only long-haul flights.
4.3.5 This has the potential to impact on population and human health in two ways. Firstly, any increase in passengers, and in turn flights, could lead to implications for current noise levels with the potential for negative impacts to arise in some areas. There may also be a need for airports to undertake operational changes to accommodate increased growth, such as changes in flight patterns or the start-up of additional routes and their destinations from Scottish airports. Such changes in operational activities could also influence current noise exposure.
4.3.6 When considering passenger and flight numbers, it is considered that the reasonable alternative of applying tax rates that would remain the same as that currently set under UK APD, represents a "like for like" approach. As such, activity in the sector would likely continue on the current predicted trajectory.
What wider context and potential mitigation measures should be taken into account?
4.3.7 Technological developments and improvements to airport operational procedures can help reduce the impact of noise by creating quieter aircraft and designing airspace and air traffic routes that aim to reduce the number of people affected by noise  . It is reported that, through improved technology, aircraft operations today are 75% quieter than they were 50 years ago  . Furthermore, design improvements offer the potential to reduce perceived noise from aircraft by an additional 65% by 2050  .
4.3.8 The main overarching policy on aircraft noise adopted by the ICAO is the "Balanced Approach to Aircraft Noise Management"  . It defines four pillars to managing noise: noise reduction through technology, noise reduction through better operation, improved noise perception through better land use planning and, if the other three pillars are exhausted, operating restrictions on aircraft such as movement restrictions and curfews.
4.3.9 The Sustainable Aviation Noise Road Map focusses on applying the ICAO Balanced Approach within the UK. The Road Map sets out four areas of work which can be prioritised to reduce noise before operational restrictions should be considered. These comprise aircraft and engine technology, operational improvements, land use planning, communication and community engagement  . However, the Road Map also notes that there are many variables, such as volume, duration, pitch and tone, that can cause someone to be annoyed by aircraft noise. While the aviation industry can control some issues, others will require a multi-stakeholder approach to resolve.
4.3.10 Airport masterplans play an important role in stakeholder engagement, in addition to their value in informing the planning process. Guidance on the preparation of airport masterplans also sets out the importance of considering noise impacts within these plans, as well as proposals for mitigation measures where major impacts have been identified  .
4.3.11 There are also a number of Codes of Practice, such as those developed by Sustainable Aviation, that set out measures that can be applied at airports to reduce the environmental implications of operational activities. The Codes consider a number of issues including the implications of noise and local air quality impacts that arise as a result of aviation activity. In some instances, measures to reduce emissions can have additional benefits, for example continual descent operations can lead to substantially smaller noise footprints than that of conventional approach procedures  .
4.3.12 Under the EU Environment Noise Directive, any airport with more than 50,000 aircraft movements a year, or that has a significant noise impact on a densely populated urban area, must produce a strategic noise map and noise action plan which must be updated every five years  . These maps are published by the Scottish Government.  . Additionally, noise action plans have been produced at a number of airports setting out measures taken to reduce the impact of noise. Although the Directive seeks to minimise environmental noise arising from aviation activities, it does not set clear noise targets or limit values  . The World Health Organisation is due to publish Environmental Noise Guidelines for the European region  . It is anticipated that this guidance will reflect latest evidence on how noise from specific sources affects health.
4.3.13 At a national level, the preferred policy option will sit within the context of a wide range of policies and proposals that set out objectives for improved connectivity. These will have implications on transport options to and from airports, with further implications on air quality. In addition, a number of airports produce surface access strategies which set out alternative travel options to and from the airport for passengers, workers and suppliers  .
What is the likely significance of the predicted impacts?
4.3.14 There are many factors that influence air quality at a local level. For example, any additional road traffic that may arise as a result of the preferred policy option would need to be considered in the context of relevant factors such as growth and changes within other sectors. Changes to air quality, and the significance of this, would also depend on factors such as the current state of the air quality in areas surrounding individual airports.
4.3.15 Additionally, the significance of any impacts on human health that arise through changes in air quality will depend on a number of factors. For example, those with existing health conditions have the potential to be more adversely affected. Furthermore, those living in areas where there are existing issues of poor air quality may already be subject to prolonged exposure from pollutants.
4.3.16 Aircraft noise is the most significant cause of adverse community reaction related to the operation and expansion of airports and this is expected to remain the case in most regions of the world for the foreseeable future  . Although noise performance has improved dramatically over the past fifty years, community perception of noise has, if anything, worsened  . Noise may affect greater numbers of people than other local issues such as air quality  and many local communities believe that the current noise metrics, including the use of average noise contours, do not fully reflect their experience of local aircraft noise  .
4.3.17 The extent and significance of any impacts will be most realised at a local level and be dependent on a number of factors, including the extent to which the predicted increase in passenger numbers are realised. In general, impacts on noise and air quality are likely to be long-term in nature; however, short-term impacts, for example noise and dust from construction activities, could also arise.
Box 4.1 Population and Human Health: Summary of impacts and key points