GEN S109/1009SEF L8 Noise Pollution PDF

GEN S109/1009SEF Environment and Health Lecture 8 Noise Pollution and Control Autumn 2024 Basic concept of sound and noise  Sound Sound is a form of energy that can be heard by human beings Sound is generated by a vibrating object and transmitted by p...

GEN S109/1009SEF Environment and Health Lecture 8 Noise Pollution and Control Autumn 2024 Basic concept of sound and noise  Sound Sound is a form of energy that can be heard by human beings Sound is generated by a vibrating object and transmitted by pressure variations through a medium (solid, liquid or gas) Example When the drum surface vibrates, it causes slight changes in air pressure These changes in air pressure travel as waves through the air or other medium and produce the sound Striking a drum surface with a stick  Transmission of sound waves Longitudinal wave A wave vibrating parallel to the direction of its propagation Two kinds of wave Transverse wave A wave vibrating at right angle (perpendicular) to the direction of its propagation Sound propagates as longitudinal waves (also called compression waves), not transverse waves It requires a medium (solid/liquid/gas) to propagate  Transmission of sound waves "Science - Transmission of Sound”. https://www.youtube.com/watch?v=av27RMbosjI String telephone Perception of sound by human ear  Perception of sound by human ear “Journey of Sound to the Brain”. YouTube, https://www.youtube.com/watch?v=eQEaiZ2j9oc  Physics of Sound Wavelength (‫)ג‬ Period (T) Frequency (f) Amplitude (A)/Intensity Speed of sound  Wavelength (‫)ג‬ Distance from a particular point on a wave to the next point that is at the same height, going in the same direction λ Wave velocity () Wavelength (‫= )ג‬ A Frequency (f) Distance Position Distance (x) Wavelength is measured in meters A λ  Period (T) Time required for one complete cycle of the wave to pass by a point T = Time taken by a wave to travel a distance of one wavelength As the frequency of a wave A ) increases, the time period of the wave y( Distance n o decreases it Tim e is Time Po The unit for time period is A “second” Formula for period: T = 1/f where T = period and f = frequency  Frequency (f) T The rate of vibration per unit Distance time measured in cycle Tim Time e 1 Frequency (f) = Period (T) T The unit of frequency is Hertz (Hz) 1 Hz = 1 wave per second  Frequency (f) “Pitch and Frequency”, https://www.youtube.com/watch?v=ZjvuiOSo3ow Human can perceive sounds in the range from ~ 20 Hz to 20 kHz Inaudible Audible Inaudible SOUND Hertz (Hz) 20 200 2,000 20,000 Low-pitch High-pitch Ultrasounds Infrasounds sounds Medium sounds (Base sounds) Dogs (> 50,000 Hz) Bat (> 100,000 Hz)  Amplitude (A) A Distance ) It is the distance between the origin and y( n o Time it Tim e crest (or trough) is Po It represents the pressure intensity and A is related to the volume or loudness A larger amplitude means a louder sound, and a smaller amplitude means a softer sound Amplitude is measured in meters dB  Amplitude (A) & Frecuency (f) “Amplitude & frequency waveform diagram examples - sound theory” https://www.youtube.com/watch?v=L-q-KFwjwDs  Speed of sound It is the distance travelled by a sound wave per unit time as it propagates through any medium Sound waves move through the medium (solids, liquids or gases) by vibrating the molecules in the matter Speed of sound depends on composition/density of media Sound waves move through the medium (solids, liquids or gases) by vibrating the molecules in the matter Speed of sound in various media: Speed of wave: < < Particles generally far apart so Particles are much closer than Particles closely packed so that the wave travel further before those in air. They can quickly the wave travels even faster they bump into one another. transmit vibration energy from than it does in either liquid or Due to less resistance to one particle to the next. The air. But a lot of energy is movement of particle, less sound wave travels > 4 times required to start the wave at the energy is needed to start the faster than it is in air, but it takes beginning wave, but the wave will not a lot of energy to start the travel fast vibration Speed of sound in various substances  Speed of sound depends on different medium The speed of sound in air at 0oC is 331 m s-1 and at 22oC is 344 m s-1 “Speed of sound in solids, liquids, and gases https://www.youtube.com/watch?v=yF4cvbAYjwI  Short summary: the physics of sound “Sound Properties (Amplitude, Period, Frequency, Wavelength) https://www.youtube.com/watch?v=-_xZZt99MzY  Short summary: the physics of sound Source: http://www.sengpielaudio.com/calculator-wavegraphs.htm  Short exercise Name the properties of sound (1) – (3) in the following figures: 2 1 3  Short exercise Which wave has the higher frequency? A B  Measurement of sound level Loudness of sound can be measured in terms pf decibel (dB) Decibels are measured on a logarithmic scale When a sound increases by 10 units on the decibel scale, its loudness becomes 10 time more powerful A small change in the number of decibels results in a huge change in the amount of noise and the potential damage to a person’s hearing  Loudness comparison in Decibels (dB) - 0 dB to 286 dB “Loudness Comparison in Decibels. Mariana Everest Comparison 1”. https://www.youtube.com/watch?v=1XUovxiTpVA  Noise = Unwanted or unpleasant sound that potentially results in annoyance and/or hearing loss From the point of view of physics, noise is indistinguishable from sound – Both arise from vibrations that happen through a medium Difference between sound and noise arises when the brain receives and perceives a sound Noise perception is subjective Factors such as the magnitude, characteristics, duration and time of occurrence may affect one to think whether a sound is a noise.  Noise? Sound you heard when you are sleeping at night Loud music in concert  Noise level and daily limits of exposure Noise level (dB) Daily time limit for exposure Examples (without hearing protection) > 130 Reaching the threshold of pain Firecracker 120 Dangerous even for a short period of time Disco music 115 < 1 minute Rock concert 109 < 2 minutes Car horn 106 3.75 minutes Video game centre 103 7.5 minutes Toy gun 100 15 minutes Music through earphones (Highest volume setting) 94 1 hour Music through earphones (Mid to high volume setting) 91 2 hours Electrical drill 85 8 hours Vacuum cleaner Source: “Bridge”, Issue No. 43 (2009), Department of Health Noise pollution  Noise can lead to hearing loss “How noise pollution is ruining your hearing” https://www.youtube.com/watch?v=z4Da0kuYnMI  Other adverse health effects “Noise Pollution Is Much Worse For You Than You Think”, https://www.youtube.com/watch?v=5jfmzufa8qo  Sources of noise pollution Environmental noise is the accumulation of all noise present in a specified environment Household sources From domestic gadgets From entertainment Indoor noises equipment Air-conditioner Crying baby TV Moving of furniture Vacuum cleaner Conversation of the inhabitants  Sources of noise pollution Social events Celebration and entertainment events Events that use loudspeaker Commercial and industrial activities Etc… Industrial machines Pumping system Air-conditioning Business-related machines such as refrigeration systems Etc…  Sources of noise pollution Construction Transportation Traffic Noise Aircraft Noise  Effects of noise pollution Effects of noise pollution generally depends on: Intensity of noise (How loud) Duration of noise exposure (How long) Frequency of the exposure (How many times during the day exposed to such a noise)  Adverse effects of noise pollution on health Hearing damage Permanent hearing loss can result from prolonged exposures to sound levels of > 85 dB Higher sound intensities require much less time to cause damage Being on the landing field without ear protection where jet planes are disembarking could cause measurable hearing losses in less than an hour Noise can also result in a temporary threshold shift which is a reversible hearing loss normally lasting from moments to hours, although longer periods of temporary hearing loss are possible Very loud explosions or gunfire can cause acoustical trauma which can rupture or damage eardrums and middle ear bones  Adverse effects of noise pollution Mental stress High blood pressure Sleep disruption Distraction Productivity loss Effects on communication Irritability and headache etc... Effects of noise pollution  Impact of noise pollution on ocean life ”How noise pollution threatens ocean life https://www.youtube.com/watch?v=0f6xWoYfGj0  Noise pollution Source Path Receiver Figure adapted from https://www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m2/types_1.html  Fundamental of noise control 1. Identify the sources of noise 2. Recognize the noise sensitive receptors and potential impact 3. Avoid the noise 4. Mitigate and reduce the noise Source-path-receiver model for noise control Figure adapted from https://https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m3/m3.html 1. Control of noise at source 2. Control along the pathway 3. Control at the receiver  Source-based noise control To avoid the production of noise or to reduce the noise level It is cost-effective and easier to implement  Sources of noise pollution Personal habits Quieter working methods or technologies Examples: Designing and fabricating silencing devices in aircraft engines, automobiles industrial machines and home appliances Maintenance/ replacement of the noisy machines Legislation Examples: Temporal and geographical restrictions of noisy heavy vehicles Restrictions for the time of construction works  Path-based noise control To control noise at the transmission pathway Installation of noise barrier Noise cancellation by absorbing or reflecting back (blocking) the sound wave energy Adding insulation and sound-proofing barrier Sound-proofing material Reflected noise Transmitted noise X Noise OR Reflected noise Absorption  Adding insulation and sound-proofing barrier “Sound wall: solving noise pollution”, https://www.youtube.com/watch?v=WotUy4xQvdw  Distance attenuation to cut down noise by zoning urban areas https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m3/m3.html  Highway noise barriers https://youtu.be/e0naL8eJmLA?si=XU3sg6C4voZrQruF Vegetation for noise reduction Reverberation control by the addition of sound absorbing material to reverberant spaces Reverberation noise Noise source  Reverberation control by the addition of sound absorbing material to reverberant spaces Video: “How to: Soundproofing & Noise Control in Factories & Industrial Facilities” https://www.youtube.com/watch?v=U47jYm4IDII  Receiver-based noise control To mitigate or reduce the noise at the receiver end To protect the receiver  Receiver-based noise control Installation of noise barrier Noise proof enclosures Noise cancellation devices Distance attenuation Depriving the receiver of an “open-window” Reduction of exposure time etc.  Summary: Fundamentals on noise control “The noise path”, https://www.youtube.com/watch?v=8Cq5UR5KssA  Planning against noise nuisance Key considerations when planning against noise nuisance Will the proposed development be sensitive to noise? Will the proposed development create noise? Are there any noise sensitive receivers (e.g., schools, hospitals etc.)? What extent of the noise impact (level and exposure time) How the noise can be avoided or reduced? Noise exposure in Hong Kong  Environmental Noise in Hong Kong Source: https://www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m2/types_1.html  Number of Pollution Complaints in Hong Kong in 2021 Source: https://www.epd.gov.hk/epd/english/laws_regulations/enforcement/pollution_complaints_statistics_2021.html Noise management in Hong Kong Noise control by the Hong Kong Government 1. Planning 2. Abatement 3. Legislation 4. Partnership  Planning Example Relocation of Airport (in 1998) Kai Tak Airport was located in the city centre and surrounded by residential buildings About 380,000 people were affected by noise of up to 100 dB from aircraft less than 100 meters overhead The airport was relocated to Chek Lap Kok in 1998 Today, the no. of people affected by the severe aircraft noise is about 200 Source: https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m4/m4.html  Planning “The Story of Hong Kong’s Kai Tak Airport” https://www.youtube.com/watch?v=8ouFX95ADTE  Planning Example Design of quieter city Source:https://www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m3/ordinance_4.html  Planning Example Earth bund Source: https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m4/m4.html  Planning Example Noise barrier in Tuen Mun Highway Source: SCMP, https://www.scmp.com/news/hong-kong/transport/article/3104057/noise-barrier-project-hong-kong-highway-enjoys-conflict  Planning Example Residential area (Receiver) Buffer zone Road (noise source) Source: https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m4/m4.html  Planning Example Podium deck Source: https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m4/m4.html  Abatement Example Roads are re-surfaced with noise absorptive materials which help to reduce traffic noise up to 5 dB Noise absorptive materials are standard features of all new highways. Source: https://www.epd.gov.hk/epd/noise_education/young/eng_young_html/m4/m4.html  Abatement Example Setting up road-side noise barriers or enclosures Paving roads with low-noise resurfacing materials Implementing traffic management scheme, such as restricting or diverting traffic at certain sensitive hours.  Legislation Noise Control Ordinance Cap. 400 (NCO); enacted in 1988 Main legislation on noise To provide statutory control to restrict and reduce the nuisance caused by noise Specifically it controls over noise from: Domestic premises and public places (general neighborhood noise) Construction activities (e.g., piling) Places other than domestic premises, public places (noise from industrial or commercial premises) Intruder alarm systems (installed in any premises or vehicles) Individual items of plant or equipment (referred to in the Ordinance as Product Noise) Motor vehicles (requiring noise emission from motor vehicles to comply with stringent international standards on the first registration in Hong Kong)  Legislation Noise Control Ordinance Any person who commits an offence under the Ordinance shall be liable to the following maximum penalties: Source: https://www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m3/ordinance_7.html#1  Legislation Road Traffic Ordinance To provide control over noise generated from newly- registered motor vehicles To provide control over aircraft noise (Stringent noise standards Civil Aviation (Aircraft have been set for aircrafts arriving at and departing from the Noise) Ordinance Hong Kong International Airport Factories and Industrial To control occupational noise generated inside the factory or other industrial activities which affects the employees working Undertakings Ordinance in these workplaces (Enforced by Labour Department)  Partnership To train and educate the operators in various sectors (e.g., the construction industry, restaurant trade, vehicle repair workshops and property management sector), which are affected by pollution control laws, through partnership programmes  Noise control in Hong Kong Construction noise Traffic noise Aircraft noise Neighborhood noise Noise from industrial and commercial activities  Construction noise Construction noise is a huge problem in Hong Kong The Noise Control Ordinance came into effect in 1989 and included controls on construction noise that have been progressively tightened Figure adapted from EPD Construction noise is mainly controlled under a construction noise permits and noise emission labels  Construction noise permit Construction noise permit must be obtained from EPD for either of the following two situations: Using specified powered mechanical equipment or carrying out prescribed construction work in Designated Areas, or carrying out general construction work using powered mechanical equipment, from 7 pm to 7 am on weekdays, and any time on Sundays and public holidays Carrying out percussive piling from 7 am to 7 pm on any day other than a public holiday  Statutory controls on construction noise applicable to different operations at different times Construction noise permit must be obtained from EPD for either of the following two situations: Using specified powered mechanical equipment or carrying out prescribed construction work in Designated Areas, or carrying out general construction work using powered mechanical equipment, from 7 am to 7 pm on weekdays, and any time on Sundays and public holidays Carrying out percussive piling from 7 am to 7 pm on any day other than a public holiday Source: https://www.epd.gov.hk/epd/english/laws_regulations/enforcement/resource_enfor4.html  Control on percussive piling Piling Figure adapted from https://www.epd.gov.hk/epd/english/ greenconstruction/poll_pro/piling.ht ml Source: https://www.epd.gov.hk/epd/english/environmentinhk/noise/data/highlights_en_pro_hk.html  Noise emission labels The Noise Control Ordinance provides the control of noise from hand-held percussive breakers and air compressors Breakers that weigh more than 10 kilograms and air compressors that can supply compressed air at 500 kilopascals or above must be fitted with noise emission labels when being used for construction work Hand-held percussive breaker Air compressor  Traffic noise https://www.epd.gov.hk/epd/misc/noisemodel1/CDROM_L10/default.html  Control over traffic noise Installing roadside barriers and resurfacing existing roads with low-noise materials Eliminating the noise problems at the outset through planning Managing vehicle under the Noise Control (Motor Vehicles) Regulation, which stipulates that new vehicles for use in Hong Kong must meet European Union and Japanese noise control standards before registration Providing soundproofing facilities to more than 10,000 school classrooms near major roads Imposing restrictions on noisy large vehicles from heavily built up residential areas during the night and the periodical or temporary blocking of some roads to traffic  Noise standards under the noise control (motor vehicles) regulation Source: https://www.epd.gov.hk/epd/misc/ehk03/eng/noise/index.html  Other control over traffic noise “Exemplary Service@Gov: New Approach to Mitigate Traffic Noise at Public Housing Development Projects”, https://www.youtube.com/watch?v=GI4gVv-Ccdw  Aircraft noise Aircraft noise is monitored by the Civil Aviation Department and quieter practices such as noise abatement procedures during take-off are required Source: https://www.epd.gov.hk/epd/misc/ehk06/eng/text/e07.02.html  Neighborhood noise Noise from domestic premises and public places Regulated under the Noise Control Ordinance (NCO) Examples of noise from domestic premises Examples of noise from public areas  Noise from industrial and commercial activities Factories and commercial operators generate noise It is restricted under the Noise Control Ordinance, as is neighborhood noise Source: https://www.epd.gov.hk/epd/sites/default/files/epd/english/environmentinhk/noise/guide_ref/Dealing%20with%20Noise%20Nuisance.pdf