Relationship between civil aircraft noise and community annoyance near Dubai International Airport

Acoust. Sci. & Tech. 33, 1 (2012) #2012 The Acoustical Society of Japan PAPER Relationship between civil aircraft noise and community annoyance near Dubai International Airport Hussein M. Elmehdi Applied Physics Department, University of Sharjah, PO Box: 27272 Sharjah, United Arab Emirates (UAE) ( Received 1 November 2010, Accepted for publication 27 June 2011 ) Abstract: According to Airport Council International (ACI) traffic statistics for 2002, Dubai International Airport is the second fastest growing airport in the world. In 2007, it catered to more than 36 million passengers, with approximately 1,000 daily flight events, including takeoffs and landings. In this paper, we report the first assessment of community annoyance caused by civil aircraft noise exposure at nine sites around Dubai International Airport (United Arab Emirates). Our aim is to assess the relationship between aircraft noise levels and annoyance responses in Dubai. To accomplish our goal, we have adapted the WECPNL and Ldn as the aircraft noise indices in Dubai, and the percentage of highly annoyed responses (%HA) has been used to assess the dose–response relationship of aircraft noise. %HA was obtained using social surveys that were carried out at nine sites within close proximity of the airport utilizing the ISO/TS 15666-2003 questionnaire. Subjects ranging between 20 and 65 years in age were randomly selected. Results show that 41% of the respondents said that they are highly annoyed, a percentage considered high but in agreement with similar studies carried out near major airports in other countries. Keywords: Airport noise, Annoyance, Dose-response, Dubai PACS number: 43.50.Qp, 43.50.Rq, 43.50.Lj [doi:10.1250/ast.33.6] 1. INTRODUCTION The number of air passengers is predicted to grow by 4.3% up to the year 2015 [1,2]. As a result the number of flights will continue to increase, especially in developing areas such as the city of Dubai, United Arab Emirates (UAE), whose airport is considered as the second fastest growing airport in the world. The airport handles close to 1,000 daily events, including takeoffs and landings [3,4], which are distributed throughout the day and night (see Table 1), with approximately the same number of landings and takeoffs. Such a high volume of events consequently leads to an increase in noise pollution in the vicinity of the airport. This has raised concerns about the adverse health effects on people living areas close to the airport. Several organizations, such as the World Health Organization (WHO), [5] have reported that exposure to high noise levels leads to induced hearing impairment; interference with speech communication and performance; sleep disturbance; and cardiovascular and physiological effects. The latest of these studies is one on hypertension and exposure  e-mail: hmelmehdi@sharjah.ac.ae 6 to noise near airports (HYENA), in which the relationship between exposure to noise generated by aircraft and road traffic near airports and the risk of hypertension was assessed [6]. The study revealed statistically significant effects of to aircraft noise on blood pressure. The number of individuals exposed to aircraft noise is difficult to estimate, but it is safe to say that a large number of houses are within the airport vicinity, where the noise levels in these areas produce sound pressure levels (SPLs) Ldn of 65 dB on the A scale or higher. These values are higher than the value of 57 dB on the same scale, which is considered to cause a high percentage of community annoyance [7]. It should be noted that Ldn is the parameter used as an indicator of the onset of what is referred to as ‘‘community annoyance’’ in early studies (e.g., Schultz, [8], who showed a strong correlation between this figure and annoyance. In Dubai, the airport is situated in the heart of the city (see Fig. 1), with commercial as well as residential bulidings in some areas within a few hundred meters of the runway. In this paper, we report the results of the first phase of an extensive study aimed at studying the effect of aircraft noise in the vicinity of Dubai International Airport. The H. M. ELMEHDI: NOISE ANNOYANCE ASSESSMENT NEAR DUBAI AIRPORT Table 1 Traffic at Dubai Internationaly . y Time of day Average number of flights 7:00–19:00 19:00–22:00 22:00–24:00 00:00–07:00 260 105 80 200 Taken from the arrival and departure tables from the Dubai International Website over a 7-day period [4]. which is characterized by major discrimination against very low frequency sounds, was used because it closely simulates the perception of the human ear. For example, a constant SPL of 57 dB indicates that the average noise produced by the source over the measurement period, which ranges from 1 to 24 h, is 57 dB. All SPL measurements reported in this paper were obtained using the A scale. The meters were placed either on rooftops or in an area clear of any obstacles. The meter was mounted on a tripod 1.5 m above ground level and at least 3 m away from any reflecting surfaces. Since the airport is quite busy throughout the day and night, measurements were performed at different times during the day and night. To confirm reproducibility, measurements were repeated at least three different times during the week. To analyze the community response to aircraft noise around the airport, we used the weighted equivalent continuous perceived noise level (WECPNL), which is given by the following expression [13]: WECPNL ¼ [dB(A)]ave þ 10 log10 ðNÞ  27; Fig. 1 Aerial view of Dubai International Airport [9]. study was started in August 2007 and comprises two phases. In the first phase, we use an integrated sound level meter to measure the noise levels at nine sites near the airport, with the goal of adding 13 more sites by the end of 2008. In the second phase, we assessed the annoyance level by means of social and socio-acoustic surveys. The questionnaire used in the survey is ISO/TS 15666-2003 (ISO Store Order #: 924549) [10]. The sites were chosen in areas close to the airport with more emphasis on residential neighborhoods. 2. MATERIALS AND METHODS 2.1. Noise Measurement As reported previously [11], noise levels were assessed using a Nor140 precision portable sound level meter (made by Norsonic, Norway). The meter is a device that responds to sound, similar to the human ear, and provides reproducible measurements of sound levels. It consists of a microphone and electronics fitted with three sound weightings A, B and C. The meter detects sounds and converts them into electrical signals via electronic circuits, from which the meter displays a digital reading for sound levels in any of the three weighted scales [12]. The A-weighting, ð1Þ where [dB(A)]ave stands for the energy mean of all peak levels of any day, and N ¼ N2 þ 3N3 þ 10ðN1 þ N4Þ, where N1 is the total number of aircraft between 0:00 a.m. and 7:00 a.m., N2 is the number of aircraft between 7:00 a.m. and 7:00 p.m., N3 is the number of aircraft between 7:00 p.m. and 10:00 p.m., and N4 is the total of aircraft between 10:00 p.m. and 12:00 p.m. In addition to WECPNL, we also calculated the day-night average sound level (Ldn ), which is given by [see, for example, refs. 13,14]   15 9  100:1Lday þ  100:1ðLnight þ10Þ ; ð2Þ Ldn ¼ 10 log 24 14 Ldn represents the average noise level over a 24-h period, with a 10 dB ‘‘penalty’’ in the night time hours (10 p.m. to 7 a.m.) to account for the fact that people typically find noise more disturbing at night while they are trying to sleep. The Ldn descriptor is useful for measuring the impact that road noise might have on establishments that may be constantly occupied such as homes. Both WECPNL and Ldn were used to assess the relationship between annoyance and public response. 2.2. Social Survey For each selected site, an average of 23 surveys were collected from residents living 100–150 m from each site. This comprised a return rate of 76%, since we have distributed 30 surveys in each site, which covered almost all of the occupied houses within the selected site. As will be discussed further in the next section, the majority of the respondents were males, which is typical in a conservative Islamic and Arab culture, where most of the house hold 7 Acoust. Sci. & Tech. 33, 1 (2012) affairs are handled by men. The questionnaire included questions about the demographics, noise annoyance, interference with daily activities, and psychological as well as physiological health-related problems, and the general reaction to aircraft noise. We used the scale developed for the ISO/TS 15666-2003 questionnaire [8], which employs a scale from 0 to 10, ranging from not annoyed at all, slightly annoyed, moderately annoyed, very annoyed to extremely annoyed. The questionnaire was made available in Arabic and English and it was left up to the randomly selected subjects to choose the language. It should be noted that the randomly chosen had no prior knowledge of the questionnaire. Subjects must have lived on their property for at least 12 months. The interviews were carried out face-to-face, and for residents who were not available, we came back to interview them on a different day. The streets selected for this study are located in the proximity of the airport: Al Twar, Mirdif, AlRashedya, Al-Muraqabat, and Qarhoud. Many subjects raised questions about the purpose of the questionnaire and it was made clear to everyone that it was a research study that will be published but will have no impact on improving or reducing the noise level. Subjects were offered the Arabic translation of the survey to help them understand the questions, but all collected surveys were completed in English. It should be noted that the vast majority of UAE residents speak English very well, as was evident from the small number of people who required the Arabic translation of the questionnaire. In addition, the subjects interviewed were all residents of the UAE who had lived near the airport for an extended period of time (at least 12 months) and were very familiar with cultural and social values of the UAE. The questionnaire was composed of three parts: a general part, which documents the site number, the date, and the noise level reading; part two, which includes questions about the demographics for each respondent; part three, which includes the following question: Thinking about the last 12 months or so, what best shows how much you are bothered, disturbed, or annoyed by aircraft noise? 8 Table 2 Responses to questionnaire. 13% 15% 31% 41% Not at all annoyed slightly annoyed/Moderately annoyed Very annoyed Extremely annoyed Fig. 2 %HA as a function of WECPNL. The middle line is a polynomial fit to the data and the upper and lower lines represent the 95% confidence limits. The solid squares are our data, while the open squares are from [16], and the open triangle from [25]. 3. RESULTS AND DISCUSSION The respondents were demographically distributed as follows: 27% female and 73% male. 43% ranged from 20 to 40 years of age, 42% were 40–60 years of age, and the remaining 15% were above 60 years of age. 86% of the interviewees were married with children, which is a reasonable number considering the conservative Islamic nature of the UAE. The results to the annoyance scale question are summarized in Table 2. WHO recommends the adoption of the percentage of respondents who felt highly annoyed (%HA) as an indicator of the health effects of noise (annoyance) and its adverse health effects [5,15]. Europe and North America, as well as Australia, also have adopted %HA as the annoyance indicator [16–18]. Since there are no regulations in the UAE, to our knowledge, that clearly indicate, which index to use, we will adopt WECPNL as a physical descriptor of aircraft noise. We will also use the Ldn indicator to compare our results with the work of other researchers. In this study, we have adopted the cutoff of 72% [8,19–23], which includes very annoyed and highly annoyed. Figure 2 shows %HA and the corresponding WECPNL values, which were calculated using Eq. (1), along with 95% confidence limits for all sites. Each point in the figure H. M. ELMEHDI: NOISE ANNOYANCE ASSESSMENT NEAR DUBAI AIRPORT tion of the noise descriptors WECPNL and Ldn and their relationship to community annoyance revealed that 41% of respondents felt highly annoyed, 31% rather annoyed, 15% slightly annoyed, and only 13% of the respondents felt not annoyed by aircraft noise near the airport. To assess the health impact of such percentages, we examined the number of %HA respondents and the WECPNL value at each site. It was found that there is a very strong relationship between WECPNL and %HA, which agrees with the conclusion of other researchers. Similar analysis using Ldn showed a similar trend. We are currently taking measurements at 13 more sites, and we plan to interview more people to further support these results. ACKNOWLEDGMENTS Fig. 3 %HA as a function of Ldn . represents the calculated WECPNL value at each site and the corresponding number of %HA respondents at that site. The figure clearly indicates a tendency for the percentage of highly annoyed people to rise as the value of WECPNL increased. This result was expected and in agreement with the results obtained by other researchers (e.g., [14,17–20]). Ldn , which was calculated using Eq. (2), is shown in Fig. 3. It should be noted that Ldn includes background noise levels, such as that arising from vehicular traffic noise. To account for the background noise levels, researchers recommend subtracting 13 dB from the WECPNL values, i.e., Ldn ¼ WECPNL  13, [16,24]. After subtraction, the values of the calculated Ldn seem to be lower than those obtained using Eq. (2), which may be partly due to the fact that the background noise level (transportation) is high, as reported previously [9]. This means that the 13 dB offset may be different for the UAE. The annoyance levels near Dubai International were found to be high but comparable to the findings of similar studies carried out near various airports around the world including Korea [16], Sweden [17], Italy [24], USA [26], Taiwan [27], Spain [28], Canada [29], India [30], and Chile [31]. 4. CONCLUSIONS The general public in the UAE are increasingly aware of environmental noise and its adverse health effects. In addition, WHO has recognized annoyance as one of the environmental health indicators that must be accounted for before deciding on various community projects and development plans. Guidelines for noise limits have been drafted in order to protect the general public from exposure to annoyance sources. Among these annoyance sources is aircraft noise, which has a high impact on people living in close proximity to an airport. At nine sites near Dubai International, where the volume of aircraft activities is considered among the highest in the world, our investiga- The author is grateful for the financial support provided by the College of Graduate Studies and Research at the University of Sharjah. The author is also grateful for the assistance of Mrs. Nawal Nayfeh for translating the survey to Arabic. REFERENCES [1] http://www.dubaiairport.com/DIA/English/TopMenu/About+ DIA/Facts+and+Figures/ [2] http://www.ameinfo.com/143493.html [3] http://en.wikipedia.org/wiki/Dubai International Airport [4] Calculated from the arrival-departure schedule over several days (see: http://www.dubaiairport.com/DIA/English/MainMenu/ Flight+Information/Arrival-Departure/) [5] WHO Guidelines to Community Noise, World Health Organization (WHO), Switzerland, 1999. 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