Aircraft Noise and Kids Health, The
LAX Study
Another Scientific Study Overlooked
in the County of Orange Environmental Impact Report for establishment of
a commercial airport at El Toro.
This summary was prepared from the
original report by a scientist member of the El Toro Airport Info Site
Team. For additional information, visit the web site on the Internet at
http://www.eltoroairport.org and e-mail inquiries to the site.
Noise pollution has been primarily linked to a loss of hearing. Recent studies, however, have suggested a link between noise and physiological processes associated with stress. These processes, including elevated blood pressure and levels of stress hormones, are considered a health hazard. Further, it was suggested that children, the sick, and the elderly are the most susceptible to noise impact, because they lack the ability to develop a coping mechanism. An inability to cope with stress can lead to increased feelings of helplessness that, by themselves, can lead to illness. The authors decided to test this hypothesis by examining the effects of aircraft noise on school children in Los Angeles.
Children were selected from the four noisiest elementary schools in the air corridor of Los Angeles International Airport. Peak noise levels reached 95 decibels (dBA), on the A scale, with one flight every 2.5 minutes. As a control group, children were also selected from three schools in quiet neighborhoods with matching socioeconomic status. A total of 262 children, from third and fourth grades, participated in task performance, on two consecutive days for 45 minutes. Children with existing hearing problems were excluded from the study.
Noise levels were measured for one hour in the two neighborhoods. Mean peaks for noisy schools were 74 dBA, as compared to 56 dBA in the quiet ones. This difference is significant because an increase of 10 dBA is considered to be twice the level of noise.
Perception. Both parents and children from the high noise schools perceived higher levels of noise at home, compared to their counterparts from the quiet schools. Further, the level of noise reported by the parents of the noise-school group increased with the length of living at the same residence.
Physiology. Blood pressures were monitored once per day and averaged. The authors noted a significant change in blood pressure between the two groups, with children from the noisy schools exhibited higher blood pressure than the children from the quiet schools.
Motivation. It has been suggested that exposure to high intensity noise can induce feeling of helplessness, which often occur when an individual cannot control or change a stressful event. This feeling, in turn, can decrease motivation to initiate new tasks and to lack of persistence giving-up. Children were administered a success-failure test where both a response to failure and giving-up are considered as indication of helplessness.
Each child was required to solve a puzzle. Half were given an insoluble (failure) puzzle, while the rest received a soluble (success) one. After the allotted time passed, all the children were required to solve a second, soluble puzzle, of moderate difficulty. The percentage of failure to solve either puzzle, as well as giving-up, was higher among the children from the noisy schools, compared to their counterparts from the quiet ones Further, the differences appeared to increase with the duration of school enrollment, for children with longer exposure to aircraft noise.
Cognitive. It has been suggested that children reared in noisy environments become inattentive to sound, by tuning it out. When this inattention includes speech-relevant sound, it may lead to reading problems. It was hypothesized, therefore, that children using such a selective inattention strategy might be less affected by noise distraction. To test this hypothesis, children were given a six-grade level essay, where, within a time limit, they were required to cross out all the e's on the pages. One test was performed while a recorded story, at a moderate voice, was playing. The second test, using a different essay, was conducted under background noise conditions to provide a baseline. A significant difference in the number of e's found was observed between the noise-school and the quiet-school groups, and it was associated with the length of enrollment in school.
During the first two years of enrollment, the children from the noisy schools did better than their quiet-school counterparts. After four years of exposure to noise, however, their performances deteriorated. The authors concluded that ìthis finding suggests that as the length of noise exposure increases, children are more disturbed by auditory distractions. Further, the authors suggested that, at first, the children attempted to cope with noise by tuning it out. Later, however, they gave up when they realized that this strategy did not work behavior consistent with helplessness data.
Last, the authors looked at 20 children from the quietest homes who were part of the noise-school group. This sub-group was more susceptible to the effects of noise, as was determined by their lower performance in several of the tests and their elevated blood pressure. Thus, living in a quiet neighborhood did not lessen the impact of exposure to noise while at school.
This study, concluded the authors, added weight to a possible impact of aircraft noise on psychological adjustment and on nonauditory aspects of health on children.
Click here for "Kids Near Airports Don't Read as Well", a new study from Cornell University researchers.
Click here for the "Munich Airport study" of Chronic Noise and Psychological Stress on children.