Welcome to NORAH
The multidisciplinary research project NORAH (Noise Related Annoyance, Cognition and Health) was aimed at providing a broad and scientifically reliable description of the effects of air, road and rail traffic noise on the health and life quality of affected residents. In order to reach this holistic aim, several scientific institutions from psychology, medicine, social science, and acoustic engineering worked together. They primarily did empirical work in the Rhine/Main area; in addition, they made interviews in the vicinity of the German airports Cologne/Bonn, Stuttgart, and Berlin-Schönefeld. The project was primarily sponsored by the State of Hesse and the Umwelthaus gGmbH; minor financial contributions came from Frankfurt Airport AG, airlines, and local communities.
The research group consists of:
The following content areas were considered: annoyance and quality of life (module 1), health (module 2, including blood pressure regulation, cardiovascular diseases, breast cancer, depression and sleep disturbances) as well as cognitive development of school children (module 3). Where possible, effects of the changes due to the implementation of a new runway at Frankfurt International Airport were considered, as well as the implementation of a night curfew between 23:00 and 05:00 hrs and the rerouting of flights.
Methods: According to the research questions, different methods were applied. In the case of noise annoyance and quality of life, systematic surveys were conducted: a panel study made up of three waves between 2011-2013 in the area of Frankfurt Airport, cross-section studies in the vicinity of the airports Cologne/Bonn, Berlin-Schönefeld, and Stuttgart. Cross-section studies were also carried out to compare the effects of road, rail and air traffic noises and on the combination of air and road traffic and air and rail traffic noise.
In the case of cardiovascular health risks, breast cancer, and depressive episodes, a case-control study based on health insurance data in combination with a detailed survey was performed in the administrative district of Darmstadt, the rural districts of Mainz-Bingen and Alzey-Worms, as well as in the cities of Mainz and Worms.
With respect to the long-term effects of traffic noise on blood pressure regulation, daily self-administered blood pressure measurements were registered for three weeks in two waves (2012 and 2013) with residents in the vicinity of the Frankfurt Airport ("blood pressure monitoring").
In order to study the short-term effects of night-time air traffic noise on the sleep of residents, sleep quality investigations were carried out in the years 2011-2013 in the homes of residents in the vicinity of Frankfurt Airport.
The effects of chronic exposure to aircraft noise on the cognitive performance and quality of life of school children near Frankfurt Airport were studied by means of performance tests (especially reading tests) with children, as well as surveys with children, parents, and teachers.
Address-specific long-term energy equivalent sound levels (LpAeq) of different reference times for air, rail and road traffic noise were available for all study participants (except for participants in the sleep study where the participants' own measurements were used) (to some extent, maximum levels as well as the numbers of loud events) and were used in the evaluations.
- At all four airports studied, the percentage of persons highly annoyed by air traffic noise at comparable noise levels was larger than would be expected from the so-called "EU standard curves" (Miedema & Oudshoorn, 2001). In the vicinity of Frankfurt Airport, in 2011 (before the implementation of a new north-west runway) higher annoyance responses were observed than during a comparable survey performed in 2005 (Schreckenberg & Meis, 2006). The annoyance response increased in 2012 (after the implementation of the new runway), and decreased marginally in 2013. In the cross-sectional studies, it turned out that aviation noise was associated with higher noise annoyance than with road or rail traffic noise at comparable long-term levels. The height of road and rail noise annoyance was very similar at comparable noise levels. In the cross-sectional studies on noise combinations (aviation plus road traffic noise, or aviation plus rail traffic noise) it was observed that the total annoyance followed mainly the aircraft noise-related annoyance.
- With respect to noise-related health risks, the largest risks connected to the 10-dB level increase were observed for unipolar depressive episodes – statistically significant with all three traffic noise sources. With respect to cardiovascular health risks, the effects of rail and road traffic noise on heart failure, myocardial infarction, and stroke were more clearly seen as compared to the effects of aviation Road traffic noise showed the highest (statistically significant) risk increase per 10-dB level increase with depressive episodes (4.1%), myocardial infarction (2.8%), heart failure (2.4%), and stroke (1.7%). Rail traffic noise showed the highest (statistically significant) risk increases with a 10-dB level increase on depressive episodes (3.9%), heart failure (3.1%), and stroke (1.8%). Air traffic noise showed the highest (statistically significant) risk increases with 10-dB level increase on depressive episodes (8.9%), and heart failure (1.6%). The use of indoor noise levels partially showed a statistically significant increase of health risks, as compared to outdoor noise levels, but it should be kept in mind that indoor noise levels were estimated rather roughly. Breast cancer showed a statistically significant association with aviation noise levels during the night (23-05h).
- Residents who were exposed to long-term aviation noise levels <40 dB but had night-time maximum levels >50 dB, showed higher health risk estimates – statistically significant with respect to stroke and heart failure. Results of this type indicate that the consideration of night-time maximum levels may be relevant for estimating the health risks of aviation noise. On the other hand, such results need further tests from independent studies.
- The mean systolic and diastolic blood pressure values of residents increased slightly (statistically not significant) with increased aircraft noise levels. Railway noise levels showed a slight (statistically not significant) increase of the systolic blood pressure. There was no statistically significant relation between traffic noise levels and pulse frequency, blood pressure amplitude, hypertension, and 10-year heart attack risk (PROCAM-Score).
- The sleep study showed a diminished aircraft noise related probability of physiological night-time awakening associated with the introduction of the night curfew at Frankfurt Airport for a group being in bed during 22:00-22:30 hrs until 06:00-06:30 hrs). On average, the number of awakenings decreased from 2.0 to 0.8 (2011 vs. 2012). This shows that the curfew had a positive overall effect on sleep. In general, there was a significant effect of the number of aircraft noise events on the number of aircraft noise-related awakenings which lead to a fragmentation of the sleep (diminished continuity), without shortening the total sleep time. In a second group, being in bed from 23:00-23:30 hrs until 07:00-07:30 h, an average aircraft noise-associated awakening frequency of 1.9 was observed in 2012. The difference to the former group is due to the longer time (one hour) of aircraft noise exposure in the morning hours. At background noise levels of 28.8 dB(A), the odds of awakening in-creased by 23 % with an increase per 10 dB increase of the maximum level of an aircraft overflight. Total sleep time, sleep latency, sleep efficiency, waking time after falling asleep, and the percentage of waking after 04:30 hrs did not differ statistically significantly between 2011 and 2011.
- Persons with a positive attitude towards air traffic did show less (objectively) measured sleep disturbances. The direction of causality is unclear, i.e., the question whether a disturbed sleep is due to negative attitudes to air traffic, or the other way round, could not be determined. The (subjective) evaluations of the residents with respect to sleepiness and tiredness in the morning are in a medium range in all of the three groups observed between 2011 and 2013. The self-assessed habituation to aircraft noise, the loudness of the residential area, the age as well as the chronotype of the participants all show a statistically significant influence on the individual assessment of sleepiness and tiredness. The subjective assessment of a good sleep diminished in spite of the introduction of the night curfew statistically significantly between 2011 and 2013 by 5 % and 11 % respectively, independently of the aviation noise exposure. This effect is also true for those participants who took part in all of the three measurement waves. This effect is probably due to factors not assessed in the study.
- In the child study a statistically significant decrease of reading performance was observed with increasing aircraft noise levels: a one-month retardation of reading performance was observed for a 10 dB increase of the long-term energy equivalent sound level. The teachers in highly exposed schools concordantly report about considerable disturbance of the classes by aviation noise. In addition, there were statistically significant connections - although of lower effect size - between energy equivalent sound levels and less positive assessments of the physical and mental well-being and children's attitudes towards
Seen from an interdisciplinary perspective, two parallel results seem remarkable:
- Medically diagnosed depressive episodes show the strongest increase with increasing aircraft noise levels, and self-assessments of mental quality of life (Mental Component Summary (MCS), including depressive tendencies) were lowest in the panel group expecting or experiencing an increase of noise levels in 2011-2013.
- Both the physiological sleep measurements and the survey on annoyance and quality of life found an improvement of sleep through the night after the implementation of the night curfew during 23:00-05:00 hrs, although the night-time equivalent sound level LpAeq,22-06h decreased by only 0.6 dB between 2011 and 2012 in the panel sample. At the same time, both studies showed an increase of negative evaluations of the participants with respect to the morning time (e.g. disturbances of late sleep, tiredness and sleepiness).