Aircraft noise emissions appear to be annoying, largely because of their intermittent nature. A meta-analysis study revealed that among all transport noise sources, aircraft noise is considered the most annoying source [1
]. Given that children are more susceptible to environmental stressors than adults because of reduced cognitive capacity to understand environmental issues and a lack of well-developed coping repertoires [2
], it is crucial to understand how they perceive and react to changes in aircraft noise exposure. This is significant especially as a related study suggests that chronic exposure to aircraft noise may undermine children’s reading comprehension performance [3
]. An understanding of the way environmental noise affects children’s development and functioning at home and school is fundamental to optimizing their learning potential and has implications for teaching practice and health.
Therefore, the present study investigates the health and annoyance reactions of children to change in aircraft noise exposure. Unlike previous studies that have explored the association between aircraft noise-exposure, annoyance and health, the strengths and uniqueness of the present study lies in its methodological design. Although laboratory studies that evaluate the impact of noise are crucial as they allow greater control of confounding variables (related to environmental conditions) than is possible in field studies, the participants are commonly exposed to only short bursts of noise during the experimental procedures and therefore generalization of the findings to chronically noise-exposed children is problematic [4
]. Furthermore, the long-term exposure to aircraft noise on annoyance and health remains unknown due to most studies employing cross-sectional designs. Longitudinal studies that explore the associations between exposure to noise, annoyance, and health are required not only to provide understanding of causal pathways between these variables, but also to assist in the designing of preventive interventions. In the present study, subjective annoyance and health reactions of children in the high noise (HN) and low noise (LN) groups are investigated through longitudinal analyses.
Although there is a growing body of literature conducted in Euro-Western countries [5
] exploring noise annoyance, not much research appears to have been conducted on the African continent. To the best knowledge of the author, only three studies [10
] conducted in this area could be located within the African continent and even so, with participants aged 12 years, and above. Furthermore, these studies adopted a cross-sectional research design, which has its own limitations. Noise pollution is often a forgotten environmental problem that is steadily growing in developing countries [13
], where compliance with noise regulations is known to be weak [14
]. South Africa as a developing country is no exception, since urban development, economic growth and the related growth in transportation, are the major pressures increasing the levels of noise. Therefore it is crucial to determine how a developing country such as South Africa fares in comparison to developed countries.
1.1. Noise Annoyance and Health
Noise annoyance encompasses broad psychological feelings which include irritation, discomfort, distress, frustration, and offence (among others) when noise interrupts one’s psychological state or ongoing activities [15
], and interferes with an individual’s quality of life. Noise could therefore indirectly result in poor health, whereby noise annoyance from chronic noise exposure may cause prolonged activation of physiological responses such as increased blood pressure, heart rate and endocrine outputs [16
]. A cross-sectional study conducted near Schiphol and Heathrow airports demonstrated adverse effects of aircraft noise on blood pressure for 9–10 year old children [17
], and similar findings were found elsewhere with children [18
]. However inconsistent findings were demonstrated on psychological health. Children attending school within the vicinity of the Heathrow Airport were found to have higher levels of psychological distress and prevalence of hyperactivity [20
]. In the Munich Airport Study, which adopted a prospective longitudinal design, effects of aircraft noise prior to and following the opening of the new airport as well as effects of chronic noise and its reduction at the old airport (i.e.
, 6 and 18 month post relocation), were studied in 326 children aged 9 to 13 years [21
]. On the basis of the three time points the children were investigated at the two airports, the findings demonstrated a significant decrease of total quality of life (i.e.
, psychological, physical, social and functional daily life) 18 months after aircraft noise exposure as well as a motivational deficits operationalized by fewer attempts to solve insoluble puzzles in the new airport area. Quality of life became worse in children exposed to noise 18 months after the opening of the airport.
Conversely, in the largest epidemiological RANCH study, no effect of aircraft or road traffic noise was found on psychological distress [22
]. Similar findings were found in 266 school children; thereby suggesting that exposure to chronic noise is not subjectively stressful [23
]. Clark and Stansfeld concluded that noise exposure may not be associated with serious psychological illness though it may impact on the well-being and quality of life of children [16
]. Given the lack of longitudinal research in this field, children’s subjective health reactions to long-term exposure to aircraft noise are thus explored in this prospective study.
Although extensive research on noise annoyance was carried out on adults there is a dearth of studies concerning children’s annoyance reactions to noise in school settings [24
]. Consistent associations between exposure to aircraft noise and children’s annoyance have been demonstrated in cross-sectional and laboratory studies conducted within the vicinity of the international airports in developed countries [7
]. A survey of over 2,000 primary school children aged 7 to 11 years in the UK exposed to different noise sources found that children were not only aware of the noise but were also annoyed by noise [29
]. Although these studies shed some light about the impact that exposure to aircraft noise may have, the crucial questions remain unanswered regarding the long-term effects of aircraft noise exposure. Specifically, more current literature is required to reveal whether prolonged exposure to aircraft noise results in high levels of annoyance, and whether such effects remain constant or dissipate after the cessation of exposure to noise. If such effects disappear, after how long do they vanish?
Few longitudinal studies have examined the effects of persistent exposure throughout children’s development. In the School Environment and Health Study, Haines and colleagues [20
] conducted a longitudinal study around the Heathrow Airport with children aged 8 and 11. Amongst their findings, exposure to aircraft noise was related to high levels of noise annoyance, though the annoyance response remained constant over a year with no strong evidence of habituation. These findings contradicted the conclusions reached from the follow-up Los Angeles Study, whereby indications of habituation of physiological stress response were suggested [31
]. It was therefore postulated that how children respond to coping with environmental stress influences reports of annoyance, more than physiological responses. In a retrospective longitudinal Munich Airport Study that took advantage of a naturally occurring experiment, which no other studies are yet to replicate, children’s affective responses to noise were investigated among 135 learners with a mean age of 10.78 [6
]. Children living in noisier areas were significantly more annoyed by noise than those not exposed to noise. However, when the airport closed down, the annoyance diminished. Quite recently, Clark and her colleagues undertook a six-year follow-up of the UK RANCH cohort of children who were exposed to aircraft noise at primary and high schools around the Heathrow Airport [32
]. These children significantly reported higher noise annoyance six years later at aircraft noise-exposed secondary school. No significant effects of noise on health outcomes were found. Although these findings demonstrate the impact of noise exposure on annoyance, they would have been more relevant for the present study had children who were tracked not been exposed to aircraft noise at high school, so that the longitudinal effects can be clearly demarcated. It would therefore be of interest to determine whether annoyance persisted or dissipated after the relocation of the airport.