5.6.58 Impacts upon traffic congestion as a result of the LHR-NWR scheme could comprise of disruption during construction, as well as changes to traffic volumes and road capacity throughout the airport operation.
5.6.59 Impacts during the construction period, though largely an unknown at this stage would add to disruption and traffic congestion, due partly to the addition of heavy goods vehicles associated with construction, though mainly due to the disruption caused by diversions and road closures required to create a construction buffer zone, though also as part of construction of the surface access enhancements (Table 5.11).
Table 5.11: LHR–NWR Related Surface Access Enhancements
Category Location Requirement
Strategic road
M4 J3 to J4 Road widening
M4 Airport Spur Road widening
M4 J2 to J3 Road widening
M4 J4 and J4B Road widening
M4 Large M4 Junction 4b replacement
M4 Higher capacity @ M4 J4a
M4 Capacity improvements to existing main airport tunnel
M25 M25 tunnelling costs (south of junction 15)
Local road network
A4 Diversion of A4 road alignment, dual carriageway
A3044 Diversion of A3044 road alignment, dual carriageway Airport Roads Airport Way/Southern Perimeter Road Interchange,
grade-separated junction and flyover/bridge structures Heathrow Road Tunnel Southern Road Tunnel/Southern Perimeter Road
Interchange
Airport One Way One way system for western campus
5.6.60 Impacts of traffic congestion within the study area during operation are uncertain, though the plans to provide additional capacity on the road network may off-set some increases in the number of road vehicles using the airport as a consequence of expansion. Any changes to traffic flows along the M4 may cause significant disruption to the wider road network, thereby having a detrimental impact upon households and the local economy.
5.6.61 Direct impacts upon both household and the local economy due to traffic congestion as a
consequence of the LHR-NWR expansion scheme for these health outcomes would be estimated to be minor adverse, of moderate intensity and would be confined temporary over the
construction period. Health outcomes as a consequence of changes to both household and the local economy due to traffic during operation of the LHR-NWR expansion scheme have been estimated to be minor adverse, of high intensity and permanent in duration.
5.7 ENVIRONMENTAL FACTORS AIR QUALITY: EVIDENCE
5.7.1 The association between health effects and exposure to air pollutants is now well established, with distinct health risks associated with exposure to particulates available at a local level207,208. 5.7.2 The impact of long term human exposure to particulate matter (PM) anthropogenic pollution is
estimated to have an effect on mortality equivalent to nearly 29,000 deaths in the UK209. There is no known threshold concentration below which NO2 or PM10 have no effect on a population’s health.
207 COMEAP 2010 The Mortality Effects of Long-Term Exposure to Particulate Air Pollution in the United Kingdom. A report prepared by the Committee on the Medical Effects of Air Pollutants. Available at: http://www.comeap.org.uk/
208 COMEAP 2012 Statement on Estimating the Mortality Burden of Particulate Air Pollution at a Local Level. Available at:
http://www.comeap.org.uk/
209 The Mortality Effects of Long-Term Exposure to Particulate Air Pollution in the United Kingdom, COMEAP, 2010
5.7.3 Many of the sources of PM are also sources of NO2. Links between the occurrence of NO2 and health effects has strengthened substantially in recent years, though some of these are co-incident with PM, as noted by the Committee on the Medical Effects of Air Pollutants210, some could be attributed to other co-existing pollutants, such as Poly Aromatic Hydrocarbons (PAH) and Volatile Organic Compounds (VOC).
5.7.4 Defra have estimated that the effect of NO2 on mortality is equivalent to 23,500 deaths in the UK annually, though this estimate has not been endorsed by COMEAP.211 Any increases in mortality are likely to be either as a result of cardiovascular and/or respiratory mortality, particularly with regards to an elevated short-term exposure to NO2212.
5.7.5 Due to the correlation between differing airborne pollutants and similar health effects, one pollutant can often mask the effects of another and it is not always possible to discreetly isolate the health effects of a single pollutant. The causal mechanism, primarily cardiovascular and respiratory, leading to increased mortality with increased exposure to particulate matter is well-founded, though processes behind NO2 contributing to cardiovascular damage, respiratory disease or cancer are less understood.
5.7.6 Currently there is no threshold concentration below which a certain air pollutant has no effect on a population’s health.
5.7.7 Studies have reported statistically significant associations between long-term exposure to NO2
and lung function in children, respiratory infections in early childhood and effects on adult lung function. Though mortality, lung cancer, and cardiovascular and cerebrovascular effects in adults are predominately weighted towards PM mass and not NO2 (studies cited in COMEAP/2014/06 Annex B213). Similar rates of mortality per 10 µg/m3 of PM2.5 and NO2 have been found in some studies.214 Though a greater effect of NO2 (6%) than PM2.5 (3%) was found on total mortality when the broader range of NO2 concentrations over PM2.5 concentrations were taken into account. The US Environmental Protection Agency215 found that there was consistent evidence in single-city studies in diverse locations but inconsistent evidence among other large cohorts of multiple US locations.
5.7.8 A meta-analysis of available long term studies on NO2 data by Faustini et al214 concluded that the magnitude of the effect of long-term exposure to NO2 on mortality is at least as important as that of PM2.5
5.7.9 Airports and their associated surface transport are clearly sources of both PM and NO2. Studies of air pollution in the vicinity of airports have been weighted towards PM, and show strong evidence of increased concentrations both in the vicinity (<1km) and extending downwind (>1km) of airports and an association with aircraft movements216,217. Other studies also show the significant impact
210 Committee on the Medical Effects of Air Pollutants, Statement on the Evidence of the Effects of Nitrogen Dioxide on Health, COMEAP, March 2015
211 Defra analysis using interim recommendations from COMEAP’s working group on NO
212 Quantitative systematic review of the associations between short-term exposure to nitrogen dioxide and mortality and hospital admissions. BMJ Open 2015;5:e006946 doi:10.1136/bmjopen-2014-006946
213 COMEAP/2014/06 Working paper: Evidence for the effects of NO2 on health Visit
https://www.gov.uk/government/groups/committee-on-the-medical-effects-of-air-pollutants-comeap and click on COMEAP discussion papers [Accessed Jan 2016]
214 Faustini A, Rapp R, Forastiere F 2014 Nitrogen dioxide and mortality: review and meta-analysis of long-term studies.
Eur Respir J 44(3): 744-753
215US EPA, Integrated Science Assessment for Oxides of Nitrogen – Health Criteria (First External Review Draft). United States Environmental Protection Agency, 2013. http://cfpub.epa.gov/ncea/isa/recordisplay.cfm?deid=259167
216 Zhu, Y. et al 2011. Aircraft emissions and local air quality impacts from takeoff activities at a large International Airport.
Atmospheric Environment 45(36):6526-6533
217 Hudda, N et al. 2014. Emissions from an international airport increase particulate number concentrations 4-fold at 10km downwind. Environmental Science and Technology 48(12): 6628-6635.
of airport activity on NO2218,219 and the potentially significant contributions of local traffic and ground support equipment.
5.7.10 With specific reference to health effects of air pollution in the vicinity of airports, many studies have drawn on existing relationships between air pollution and health outcomes (such as those described above) to infer health impacts in the vicinity of airports. There are fewer direct studies of health impacts. Lin et al (2008) 220 indicate potentially increased risk of hospital admissions for residents living in proximity (<5km) to airports, although they note that effects are likely to be dependent on airport-specific factors. In contrast, Lavicoli et al (2014)221 suggest that the direct evidence of association between air pollution and health effects on workers and residents is still limited. Notwithstanding this, evidence is emerging of the impact of aviation emissions at multiple scales, from near-airport to regional scales222.