Prevalence of Traffic Noise in Jalandhar City

Noise Pollution

Noise pollution is a disturbance to the human environment that is escalating at such a high rate that it will become a major threat to the quality of human lives. Noises in all areas, especially in urban areas, have been increasing rapidly. Poor urban planning gives rise to noise pollution. In simple terms, noise is unwanted sound. Sound is a form of energy which is emitted by a vibrating body and on reaching the ear causes the sensation of hearing through nerves. Sounds produced by all vibrating bodies are not audible. The frequency limits of audibility are from 20 HZ to 20,000 HZ.

Sound pressure level (SPL) or sound level Lp is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level. The commonly used reference sound pressure in air is Pref = 20 µPa (rms), which is usually considered the threshold of human hearing.

Sound Intensity

• For a specified direction and point in space, the average rate at which sound energy is transmitted through a unit area perpendicular to the specified direction. The measure of a ratio of two sound intensities is

0 10log I L dB I   =    

1 1 10

If I0 is the standard reference sound intensity 12 2 0 10 / I W m − =

(W = watt), then instead of "dB SPL" we use "dB SIL". (SIL = sound intensity level).

Permissible Noise Level Criteria

The permissible noise pollution criterion is shown in Table 1. Day time shall mean from 6.00 a.m. to 10.00 p.m. Night time shall mean from 10.00 p.m. to 6.00 a.m. Silence zone is defined as an area comprising not less than 100 meters around hospitals, educational institutions and courts. The silence zones are zones which are declared as such by the competent authority. Mixed categories of areas may be declared as one of the four above mentioned categories by the competent authority.

Traffic Noise and its Health Effects

Traffic noise has become one of the main environmental quality problems in developed countries and causing noise annoyance among the citizens. In Europe about 113 million citizens (17% of the population) are exposed to ambient noise levels above Leq 65 dB(A) and about 9.7 million citizens are exposed to noise levels above 75 dB(A) [1]. The main source of acoustic nuisances is road traffic. There is a growing amount of evidence that road traffic noise increases about 1-3 decibels a year in most cities. According to prognosis, the noise load will double in a 15-year period [2, 3]. Excess noise has a wide range of effects on individuals, ranging from disturbance to chronic stress and damage to hearing. Therefore, the World Health Organization (WHO) has attributed noise to occupational risk factors [4]. Traffic noise causes annoyance, emotional distress, and chronic stress and increases the risk of hypertension [5, 6, 7]. Long-term noise causes changes in homeostasis, which are accompanied by disorders in heart rhythm, muscle tenseness and changes in brain electrical potentials [8]. A positive association was found between noise annoyance and serum lipid levels [9], exposure to noise and fibrinogen, and plasma viscosity [10], causal risk factors of ischemic heart disease (IHD). Exposure to noise increases physiological stress indicators – catecholamine’s and steroid hormones and through the neurohumoral pathway stimulates changes in the cardiovascular system, stimulates arterial hypertension, development of IHD [11, 12], and might increase myocardial infarction (MI) risk [13, 14]. There are only a few published community studies, among them Berlin case-control study [15, 16] and Cearphilly and Speedwell cohort studies [17]. Epidemiological studies have shown that noise-induced health effects depend on noise character and exposure time, as well as duration and other environmental factors. Individual sensitivity, age and susceptibility to noise determined noise- induced responses. Large individual differences in sensitivity to noise co-vary with expressed annoyance resulting from noise. Lack of measurements of noise levels in human settlements, difficulty in exposure quantification and the small number of cases are factors of great importance why epidemiologic evidence of cardiovascular effects caused by environmental noise exposure is still limited. Additional studies since then have also found an association between work-related noise and blood pressure [2, 3, 4, 5]. Although one of the studies has suggested the effect is only transient in people under the age of fifty. Possible biological mechanisms for the association between noise and high blood pressure are: 1) release of stress hormones such as steroids; and 2) activation of the sympathetic nervous system with release of epinephrine. Animal models have shown both these changes. Additionally, a recent article demonstrated genetic changes (damage) in rat heart cells. These changes persisted after noise exposure ceased [6]. Finally chronic noise exposure has been associated with hyperlipidaemia [7]. Hyperlipidaemia may by causing atherosclerosis increase the risk for hypertension.