Low frequency noise; Frequency; A sound level; Pregnancy; noise criterion
Harm of low-frequency noise in urban residential areas to human health
Objective to prove the harm of low-frequency noise to human health, especially to the elderly, pregnant women and newborns. Methods By analyzing the acoustic characteristics and propagation mode, the conclusions were proved by citing various charts and data of the workers who have been exposed to high and low frequency noise for a long time. Results and conclusions remind relevant departments to take measures to protect urban acoustic environment and ensure the health of enterprise employees and urban residents.
Keywords low frequency noise; Frequency; A sound level; Pregnant; noise criterion
A good environment, healthy, quiet and comfortable life in modern urban residential quarters is what people yearn for and pursue after the improvement of living standards, and it is also a sign that Chinese urban residents have reached a well-off living standard. However, this is not the case in many urban residential areas in China. Environmental noise pollution is the main hot spot of residents' complaints in urban residential quarters at present, and low-frequency noise is the invisible killer in environmental pollution.
1 Source and propagation mode of low-frequency noise
1. 1 the sound source of low-frequency noise The so-called low-frequency noise refers to the sound with a frequency below 500 Hz (octave). There are five main types of low-frequency noise sources in residential quarters: elevators, transformers, water pumps in high-rise buildings, central air conditioning (including cooling towers) and traffic noise. The Institute of Environmental Pollution Control Technology of Zhejiang University used acoustic instruments to test and analyze the noise sources of supporting equipment in typical residential quarters in Hangzhou, and selected noise sources such as power supply system, underground garage, elevator equipment, heating system, drainage and water supply system, air conditioning equipment and ventilation equipment. The results show that among 12 typical noise sources, the low frequency band is the most. Therefore, low-frequency noise has become the most influential noise source in residential areas [1].
1.2 Acoustic characteristics of low-frequency noise Low-frequency noise is different from high-frequency noise. High-frequency noise will decay rapidly with the increase of distance or obstacles. For example, the point source of high-frequency noise can reduce 6 decibels per 10 meter. However, the low-frequency noise gradually decreases, and the sound wave is longer, so it can easily cross obstacles, rush a long distance, cross walls and go straight into people's ears. Vibration, low-frequency noise and general noise all have the same property, which is a vibration wave and a way of energy transfer.
1.3 The propagation paths of low-frequency noise are mainly divided into structural sound propagation, airborne sound propagation and standing wave, among which the standing wave is the most harmful. Structural sound transmission refers to the transformer, water pump and central air conditioner installed in the building, which transmits low-frequency vibration sound waves to all residents through the basic structural beams and load-bearing beams of residential buildings. Air-borne sound refers to the direct transmission of low-frequency noise to residents' families through the air. Standing wave refers to the standing wave formed by repeated reflection of low-frequency noise during propagation. The amplitude of low-frequency noise is the strongest at the antinode, which is the most harmful to human health.
Low-frequency noise is harmful to health
All noise will do harm to human body. Although the direct impact of low-frequency noise on physiology is not as obvious as that of high-frequency noise, low-frequency noise will have a long-term impact on human health. However, people have not paid enough attention to the harm caused by this low-frequency noise. Below we can draw a conclusion from the scientific research of experts at home and abroad and the investigation and analysis of workers exposed to low-frequency noise in production enterprises.
2. 1 Health hazards to pregnant women and fetuses
2. 1. 1 is harmful to the health of pregnant women. Medical researchers at home and abroad have done a lot of research in this field, which proves that strong noise will have many adverse consequences for pregnant women and fetuses. Pregnant women may have nausea, vomiting and other reactions in the early stage of pregnancy. Some people react badly enough to affect eating, and some even need infusion treatment [2]; In the investigation of female workers in loom workshops of three textile mills in Anyang City, Henan Province, it was found that there were significant differences between the contact group and the control group in pregnancy anemia, spontaneous abortion and pregnancy-induced hypertension syndrome (P < 0.0 1, P < 0.05) [3]. See table 1. Table 1 Comparison of pregnancy process and pregnancy outcome between female workers exposed to noise and control group Note: By chi-square test, compared with control group, * P < 0.05, * * P & lt0.0 1
2. 1.2 Exposure to strong noise will not only do harm to the health of pregnant women, but also have many adverse effects on the fetus. In the 1970s, a survey was conducted on residents living near foreign international airports. It is found that the weight of babies born in local residents is lower than that of newborns in other areas, indicating that strong noise may affect the development of the fetus [4]. Nutritionist researchers have found that noise will not only reduce human immune function, but also increase the consumption of vitamins C, B 1, B2, B6, amino acids, glutamic acid, lysine and other nutrients in human body, which will have a negative impact on children's growth and development.
Chinese scholars tested the children of female workers exposed to strong noise (above 95 decibels) during pregnancy and compared them with other children with similar conditions, and found that the IQ level of the former was lower than that of the latter. The reason may be that noise often causes uterine contraction, which affects the blood supply of the fetus and then affects the development of the fetal nervous system.
When investigating female workers in loom workshops of three textile mills in Anyang City, Henan Province, it was also found that the incidence of full-term low birth weight and mental retardation in noise exposure group was significantly higher than that in control group, which confirmed this conclusion [4]. See Table 2. Table 2 Comparison of offspring development between noise exposure group and control group Note: By chi-square test, compared with control group, * P
In addition, the exposure of the mother to strong noise will also have adverse consequences on the hearing development of the fetus. Studies abroad show that pregnant women are exposed to strong noise (100 dB or more) during pregnancy, which increases the possibility of hearing loss in infants. This may be because noise has a direct inhibitory effect on the auditory system in fetal development. Children are immature, and their tissues and organs are very delicate and fragile. Whether the fetus or the newborn child is in the body, noise will damage the hearing organs, leading to hearing loss or loss. According to statistics, there are more than 70 million deaf people in the world today, and a considerable part of them are caused by noise. Expert research has proved that indoor noise at home is the main cause of children's deafness. If you live in noise above 85 decibels, the deaf can reach 5% [5].
2.2 Infrasound's influence on human body and animals: Infrasound has a variety of physiological and psychological effects on people. Psychological influence is mainly annoyance, and physiological influence is mainly that when infrasound is strongly stimulated, it can cause middle ear compression, earache, tympanic membrane injury, tinnitus, headache, nausea, vomiting, imbalance and blurred vision. It has also been reported that infrasound can cause abnormal changes in blood pressure, heart rhythm and breathing.
With the rapid development of industry, national defense and science and technology, the impact of noise and low-frequency noise on the environment has attracted the attention of all walks of life. Infrasound exists widely in human living environment. Although it is not felt subjectively, it has a serious impact on the human body. According to the research data, infrasound has different degrees of damage to human organs, even irreversible damage, which is more serious than noise damage. So far, foreign countries have carried out research in this field, while domestic research has just started and the research is not systematic enough. We should pay enough attention to this in order to provide protective measures to reduce the damage [6].
2.3 Harm to people's hearing and cardiovascular system Through the investigation of a thermal power plant, medical researchers learned about the impact of low-and medium-frequency noise exposure on the health of power producers. The results showed that the hearing loss of workers exposed to low-frequency noise of 0.5~6 kHz was significantly higher than that of the control group (P < 0.0 1), and the detection rates of high-frequency hearing loss and speech-frequency hearing loss of workers exposed to noise were significantly higher than that of the control group (P < 0.0655).
Harm of low-frequency noise in urban residential areas to human health
The detection rate of abnormal ECG was significantly higher than that of the control group (P < 0.0 1). In addition, sinus bradycardia, sinus arrhythmia and myocardial ischemia are the most common ECG abnormalities, which have significant differences compared with the control group (P < 0.0 1), as shown in Table 5. Table 5 Abnormal detection of blood pressure and electrocardiogram in noise exposure group and control group Note: Compared with control group, * * P < 0.0 1
Conclusion: Exposure to low-frequency noise can damage workers' hearing system, nervous system, cardiovascular system, digestive system and metabolic function. Therefore, it is necessary to take effective preventive measures against noise hazards in thermal power plants to protect workers' health [7].
2.4 Impact on blood sugar and blood lipid: The productive noise of thermal power plant is mainly continuous steady-state noise with medium and low frequency and wide frequency band. According to the results of two consecutive three-year occupational hygiene surveys, noise stimulation can affect the regulation of endocrine through auditory pathway, and the influence of noise on blood lipid is manifested by the increase of serum triglyceride and cholesterol content. See Table 6. Table 6 Abnormal detection of blood sugar, blood lipid and cholesterol in noise exposure group and control group Note: Compared with control group, * * P
3 Problems existing in national standards and measurement methods of low-frequency noise
At present, there are more and more complaints about low-frequency noise in urban residential areas, but there is no standard for low-frequency noise in China's current environmental noise standards. Therefore, when measuring low-frequency noise in urban residential areas, the decibel number of sound level meter often conforms to the current noise standard and does not exceed the standard.
Measurement methods such as GB/T 14623-93 "Standard Measurement Method of Environmental Noise in Urban Areas" and GB/T 12349-90 "Measurement Method of Noise at the Boundary of Industrial Enterprises" all use A sound level of sound level meter to measure and evaluate environmental noise.
Because the weighted frequency characteristic curve greatly attenuates the low and high frequency bands of noise, it does not attenuate the middle frequency band. Its frequency characteristic curve is like the bottom of an inverted pot, high in the middle and low at both ends. Therefore, when measuring low-frequency noise with sound level, the sound level of low-frequency noise has been greatly attenuated and the instrument cannot display it. The existence of low-frequency noise can only be truly and objectively reflected by linear scale or C sound level scale, but there is no linear scale or C sound level scale to measure environmental noise in the current national environmental noise measurement methods. This is the deficiency of national environmental noise standards and measurement methods. It is understood that the country is planning to formulate environmental standards and measurement methods for low-frequency noise.
4 conclusion
Through the above investigation and demonstration, it shows that urban low-frequency noise is really harmful to human health, and all levels of urban environmental protection departments, health and epidemic prevention departments, urban construction design and planning departments, transportation departments and real estate developers should attach great importance to it, and should earnestly implement the spirit of "people-oriented" and formulate environmental standards related to low-frequency noise as soon as possible. Attach importance to the protection of urban acoustic environment, strengthen all aspects of protective measures, protect women and children, protect urban residents, and protect the health of enterprise employees.
refer to
1 Peng Yu, Huo Guoqing, Huang Yifan. Analysis of frequency characteristics of equipment noise in urban residential areas. China environmental science, 2006,26 (40): 491-495.
2 Xiao Quanhua,, Tan,. Retrospective cohort study on the effect of noise on the pregnancy outcome of female reproductive function. China occupational medicine, 200 1, 28 (3): 42-44.
Wei saw that the noise in the elevator was unbearable. Global Times Life Weekly, 2005- 1 1-29(5).
4 Anonymous. Effect of noise on pregnant women and fetus. Beijing Youth Daily, August 2005-1(6).
5 Jia Ning. Low frequency noise can not be ignored. Global Times, 2004- 10- 12(20).
6 Du Fu, Ji Baichun. Research progress on the effects of infrasound on human body and animals. Foreign Medical Otolaryngology Department, 200 1, 25 (2): 99- 102.
7 Liu. Investigation on the influence of low and medium frequency noise on the health of electric workers. Occupational and Health, 2003, 19 (12): 33-35.
8 Jiang, Liu Airong. Effect of noise in thermal power plant on blood lipid and blood sugar of workers. Occupational and Health, 20, 2004 (11): 42-43.
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