Road traffic noise and annoyance: exposure-response relationship and burden of disease calculations in Bulgaria

Background: Noise annoyance (NA) contributes considerably to the cumulative burden of disease from environmental noise in Europe. Exposure-response functions are the basis for assessment of its socio-economic impact which is essential for environmental health policy. These functions have not been implemented in Bulgaria. Aim: In order to determine the socio-economic impact of road traffic NA in Plovdiv and Bulgaria several objectives were set: to establish a preliminary exposure-response relationship between road traffic noise and NA; to compare it to Miedema and Oudshoorn`s curve recommended by the World Health Organization (WHO); and to quantify the burden of high NA. Material and methods: Based on data collected during a survey on cardio-metabolic environmental risk factors in Plovdiv we generated an exposure-response function derived from a logistic model and compared it to Miedema and Oudshoorn`s polynomial. Employing the official WHO methodology we calculated the disability-adjusted life years (DALYs) lost in Plovdiv due to high NA and monetized the value of these DALYs. Then we extended the analyses to the total Bulgarian urban population. Results: The logistic function in our study bared close resemblance to Miedema and Oudshoorn`s polynomial (range 55-75 dB). Based on the latter, a n annual loss of 1 188.17 DALYs was estimated in Plovdiv which translated into € 14.26 million assuming € 12 000 per DALY. On a national scale the results were even more alarming (6 399.60 DALYs and € 76.80 million). Conclusion: Road traffic NA appears to have a considerable socio-economic impact in the country which calls for decisive actions by involved authorities. Future use of Miedema and Oudshoorn`s polynomial is substantiated.