The levels of aircraft noise considered acceptable by Department for Transport (DfT) are significantly higher than the levels recommended by the WHO. Moreover, the basis used by the DfT for measuring aircraft noise - the dBA leq (decibel level equivalent) - does not portray the true impacts because it averages out aircraft noise, typically over a 16-hour day and an 8-hour night.
Periods of relative silence between aircraft noise events reduce the average. During this 16-hour day, the DfT considers noise levels up to 57 dBA Leq to be generally acceptable or, using an alternative measure, 55dBA Lden (see below). (Night noise at Stansted is ‘regulated’ by the DfT in a different way based on limiting the number of night flights and the noisiness of individual aircraft.)
The maximum aircraft noise exposure levels recommended by the WHO are set out in their 2018 Environmental Noise Guidelines for the European Region, as follows:
For average (24-hour) noise exposure, the WHO “strongly recommends” reducing noise levels produced by aircraft below 45 dB Lden, having concluded that aircraft noise above this level is associated with adverse health effects. For night noise (11pm-7am), the WHO “strongly recommends” reducing noise levels produced by aircraft to below 40 dB Lnight, having concluded that aircraft noise above this level is associated with adverse effects on sleep.
[Note that the WHO recommendations are based on noise measurement yardsticks which are slightly different from those used by the DfT. Lden is the average over Leq over a 24 hour period (day/evening/night) with a 5dBA weighting for evening and a 10dbA weighting for night. Lnight is the average Leq over the period from 11pm to 7am.]
It is important to note that the dBA scale is logarithmic whereby an increase of 10dBA amounts to a doubling of the noise detected by the human ear.
The levels of aircraft noise considered acceptable by the DfT and the aviation industry are about twice the maximum level “strongly recommended” by the WHO for the avoidance of adverse health effects.
There is ongoing reluctance on the part of the DfT to follow the scientific advice provided by the WHO such that it is difficult to avoid the conclusion that the DfT attaches greater weight to the financial interests of the aviation industry than to the health interests of the wider population, especially those who live near airports and/or under flight paths.
The evidence underpinning the 2018 WHO Guidelines is loud and clear and should be the catalyst for revised policies and actions to ensure there is an equitable balance between economic benefit and the health and wellbeing of communities. The cost and long-term consequences of inaction will be considerable.
Aviation noise should not be considered in isolation. Atmospheric pollution engendered by aircraft and higher levels of road traffic in the vicinity of airports can act in conjunction with aviation noise to induce pulmonary disease, particularly in children.
Also of major importance, but only recently highlighted, are the findings from studies conducted in Europe and the UK which have shown that aircraft noise has substantial effects on cardiovascular disease including hypertension, ischaemic heart disease, heart failure and stroke. Aviation noise particularly at night causes increased blood pressure as stress hormone levels rise. Recently published scientific literature on the effect on cardiovascular disease needs to be brought to the attention of health authorities.
Aircraft noise can have particularly damaging impacts on both the health and the education of children. Primary school children exposed to noise experience reduced cognitive performance. The term “jet pause” is well known to those teaching and learning in schools near to Heathrow resulting from continual interruptions in communication from low flying aircraft disturbing classroom activity every 60-90 seconds. The Munich Airport Noise Study, 1996, showed that long term memory and reading deficits in schoolchildren were reversed when the airport was moved, but emerged in children near the new Munich Airport. Worryingly, stress responses such as an increase in systolic blood pressure and higher levels of resting adrenaline and norepinephrine were also recorded when compared with children not exposed to chronic aircraft noise. Although levels were raised, they were not clinically significant at that time.
Sleep disturbance may occur at all ages, although there is considerable variation even within families. Sleep disturbance results in fatigue and accidents from concentration failure, especially whilst carrying out complex tasks; children take examinations which may affect their future. Indeed, environmental pollutants, including noise, may have a permanent effect on a child’s academic potential and wellbeing.