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Istituto Superiore di Sanità
EpiCentro - L'epidemiologia per la sanità pubblica
Istituto Superiore di Sanità - EpiCentro


Evaluation of health effects in a sample of women living near Malpensa Airport, 2000

Salvatore Pisani1 - Domenico Bonarrigo1 - Maria Gambino1- Luigi Macchi1 Cristina Degli Stefani1 - Anna Maria Verri1 Cesare Cislaghi2 - Anna Bossi2 - Ivan Cortinovis2

1 Local Health Authority of the Province of Varese

2 Institute of Medical Statistics and Biometry, University of Milan, Milan

 

Noise can have harmful effects on human health (1), especially in persons living near airports (2,3). During the month of Cotober, 198, Malpensa Airport near Milan became an international airport, and the increased flight activity elicted concerns among nearby communes about possible adverse health effects.

 

To evaluate the health status of this population, the Local Health Authority of Varese conducted an epidemiologic survey in collaboration with the University of Milan and with general practitioners. A total of 92 general practitioners and 932 housewives, sampled from the population lists of 11 communes, stratified into 3 different exposure levels, were involved. The exposure levels were based on the level of dB(A) of type A decibels, which are the unit of measure of sound intensity, as evaluated by a summary measure known as the LVA, which is the level of evaluation of airport noise that takes into account daily noise in pre-determined periods during the day and night. For purposes of the study, Area A included the communities of Somma Lombardo, Arsago Seprio, Casorate Sempione e Lonate Pozzolo, which were most heavily exposed to noise at LVA (dB(A)) di 60-64; Area B included Samarate, Cardano al Campo, Vizzola Ticino, Ferno, Golasecca e Vergiate(LVA values between 55 and 59); and Area C consisted of the Masnago and Avigno neighborhoods of Varese which were far from the airport and were considered non exposed to airplane noise (LVA < 55).

 

The survey, known as Salus Domestica, took place between May and November 2000 and consisted of collection of information on the state of health of women by their general practitioners. The information on pathologies observed within the past two years was obtained from the records of the general practitioners, while the data on perceived problems during the previous year was obtained by a questionnaire. The percent of women responding was 79%.

The sample consisted of 387 women in area A, 253 in area B and 292 in area C. Noise was considered a continual source of bother by 98% of those living in area A, 73% of those in are B, and 38% in those of area C. “I am dissatisfied”, “night-time awakening”, “state of anxiety”, and “difficulty understanding words” were core commonly reported in area A than in area C, with odds ratios just under 3; furthermore, the general practitioners reported that in the past two years, the women of area A had a higher prevalence of headaches with respect to area C and a higher prevalence of allergies and nervous anxiety than areas B and C (Table).

 

In the last year, the number of women who had been seen by their general practitioner or by a specialist was significantly higher in area A than in the other areas, as was the number who had received anti-anxiety agents (24%) or sleeping pills (14%). Review of the general practitioner records indicated a higher prevalence of visits for headaches, allergies, and nervous anxiety in area A, but no excess of respiratory disease or of hearing problems, although the women in the area complained of higher rates of respiratory disturbances and difficulties hearing conversation than did those of the other areas.

 

An exploratory multivariate procedure, analysis of multiple correspondences, demonstrated a considerable coherence among the responses given by the women and the information from their practitioners. With the same analysis, there were no associations found between self-reported or physician-diagnosed symptoms and age, education attainment, type of house, or birthplace of the women despite the fact that there were differences in the educational levels between the three study areas.

 

In conclusion, the complaints of the housewives living near Malpensa were primarily in the realm of interpersonal and stress disorders (anxiety, insomnia, and difficulty hearing conversations) and, to a more minor extent, in respiratory complaints, although this latter finding was not supported by an increased rate of diagnosis of respiratory diseases. The data did not allow us to distinguish the effects of noise from an increased concern on the part of the population about possible health effects arising from the airport expansion.

 

Comment

Susanna Lagorio

Laboratory of Epidemiology and Biostatistics, ISS

 

Noise can cause adverse health effects: deafness, hypertension and cardiovascular disease, interference with verbal communication, sleep disturbances, and adverse behavioral, relational, and social effects. Safe levels of exposure vary with respect to the type of outcome in consideration, the type of noise, and the susceptibility of the exposed individuals.

 

The authors conducted an epidemiologic study on the health effects of the residents in the Communes surrounding Malpensa: nearly 1000 women between 18 and 64 years who spent no less than 16 hours a day at home. On the basis of measurements conducted in 2000, the area was divided in three zones at increasing distances from the airport, with area A being exposed to the highest levels (LAeq, 24 h 60-65 dB(A)), and levels of reported symptoms and diseases diagnosed by general practitioners were compared between the three.

 

Women in area A had significantly higher rates of respiratory complaints, anxiety, relational problems, and sleep disturbances than those living further away. Their physicians did not report, however, any difference in levels of diagnosing hearing problems, acute and chronic respiratory diseases, and depression between the various areas, although the women living in area A were significantly more likely to have been diagnosed with headache, nervous anxiety, and allergies.

 

The lack of hearing problems diagnosed in area A is in agreement with the standards of exposure to noise that are in place in most countries (ISO 1990), which state that the risk of hearing loss is not important at lifetime exposes to Laeq (24 h) less than 70 dB (A).

 

Increments in levels of hypertension and cardiovascular disease are well-documented only in relation to work-related noise that is both very intense and of long duration, while the scientific evidence of the cardiovascular effects of environmental noise suggest a weak association with the risk of hypertension, without a clear dose-response (4). Thus, the lack of increased rates of hypertension among the women of area A seems to be in agreement with available scientific evidence. With respect to difficulties with understanding conversation, the issue is not so much the intensity of external noise but the relationship between volume of the voice and background noise (signal-to-noise ratio). To guarantee good intelligibility of conversation among persons with normal hearing, this ratio must be of 15-18 dB(A). The normal volume of conversation between two persons a meter apart is about 50 dB(A). Persons with non-compromised hearing function, to maintain 100% comprehension, must increase their voice level in the face of noise levels greater than 55dB(1), to the point of reaching vocal “stress” when the level of background noise is superior to 65 dB(1). For susceptible persons who have compromised hearing the “stressful” level of background noise is lower.

 

The effects of noise on the quality of sleep seem to be especially a function of night time noise, especially the number, intensity, and timing of noisy episodes. It is estimated that 80-90% of the sleep disturbances in noisy environments are in reality due to causes other than external noises (for example, noise from neighbors, worries, illnesses, and climate (4).

 

In conclusion, the residents of the Communes situated near Malpensa feel much less healthy the closer they live to the airport, but this perception does not translate at the moment in to measurable health effects that can be directly attributed to noise exposure from airplane traffic. The perception has lead to an increased request for assistance by general practitioners in the area, who have responded with increased prescription of anti-anxiety drugs.

 

Bibliography

1.   World Health Organization. Adverse health effects of noise. In: Guidelines for community noise, chapter 3. .Berglund B, Lindvall T. Schwela DH, eds. Geneva, 1999.

2.   Kinney PL, Ozkaynak H. Association of daily mortality and air pollution in Los Angeles County. Environ Res 1991; 54 (2): 99-120.

3.   Kryter KD. Aircraft noise and social factors in psychiatric hospital admission rates: a re-examination of some data. Psychological Medicine 1990; 20 (2): 395-411.

4.   Dumser B, Bishop B, Burke M et al. Whintrop Health Study 1999. (http://airhealthwatch.com/airorg.htm).