Title: 5-Noise Pollution - Lecture slide.ppt
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Markdown Content:
# Week 5
# Noise Pollution
# Overview Topics
# Characteristics of Noise
# Sources and effects of Noise:
# Measurements of Noise
# Noise Control
# Managing noise
# Malaysia Law on Noise Definition:
-Noise pollution refers to the presence of excessive, unwanted, and disruptive sound that negatively impacts human health and the environment.
- It is characterized by sounds that are louder, more frequent, or of a different nature than the surrounding ambient noise. Characteristics of Noise:
Frequency :
- Noise ranges from low frequencies <80 Hz (infrasonic/inaudible) to high >20,000 Hz (ultrasonic).
- Pitch is perceived for sounds from 80 Hz-4,000 Hz. Low frequencies travel further.
Amplitude:
- Loudness is measured in decibels (dB) or dB(A) accounting for human sensitivity.
- Noise levels above 80 dB can damage hearing over prolonged exposure.
Time Pattern:
- Continuous noise is unvarying while intermittent has regular breaks.
- Impulsive/impact noise like gunshots cause abrupt changes in pressure.
Other characteristics:
- Tonal quality (pure/complex tones)
- Temporal characteristics like rise/fall time
- Subjective perception depends on context and individual factors. Sources and effects of Noise:
Sources of Noise:
Industrial Activities:
- Large stationary machinery have prominent low-frequency components that propagate farther.
- Metal fabrication operations involve power tools, sawing, drilling that generate variable noise.
- Boilers and cooling towers produce broadband noise from steam/air flows.
Transportation:
- Traffic flow density and vehicle speed are important determinants of road/aircraft noise levels.
- Rail amenities like horns, loud speakers, track/wheel interaction are major noise sources.
- Use of older public vehicles, modified exhausts/mufflers increase vehicular noise pollution.
Construction:
- Pile driving, rock breaking, excavation, bulldozing are impulsive/impact noise sources.
- Concrete mixers, cranes, trucks manoeuvring/reversing emit intermittent noise.
- Construction typically occurs over shorter periods than stationary sources.
Urbanization:
- Mixed land use, high population density mean more noise from various human, vehicular activities.
- Growing urban sprawl brings commercial, entertainment zones closer to residential areas.
- Noise levels depend significantly on time of day, day of week. Effects of Noise:
Human Health Effects:
- Hearing impairment ranges from mild (>25dB) to severe (>40dB) and noise-induced hearing loss is irreparable.
- Chronic noise exposure leads to hypertension, increased heart rate, sleep disorders, annoyance and loss of productivity.
- Noise above 85dB also causes physiological stress responses affecting immunity.
Environmental Effects:
- Alters animal communication distances, masking important sounds like predators or nurturing calls.
- Chronic noise disrupts foraging, breeding and migratory patterns negatively impacting reproduction and population growth.
- Underwater noise from shipping, seismic activities, pile driving impede orientation, navigation and hearing abilities of aquatic life.
- Loud intermittent sounds like sonars can cause stranding or death of sensitive marine mammals.
Indirect Effects:
- Declining biodiversity and wildlife habitats impacts ecosystem services vital for human well-being.
- Noise disturbances near protected natural areas and reserves degrade the intended conservation functions. Measurements of Noise
Noise measurement techniques:
Sound Level Meters:
- Measure amplitude in dB and frequencies using microphones and digital displays.
- Captures metrics like Leq, L10, L50, L90 relating to average, peak levels over time.
- Handheld or permanent meters help identify noise sources and monitor trends.
Noise Mapping :
- Uses noise modelling software along with Geographic Information Systems (GIS).
- Considers factors like infrastructure, topography, meteorology, traffic patterns.
- Produces visual maps showing spatial distribution and propagation of noise levels.
Standards:
- WHO guidelines suggest outdoor day-evening-night noise levels of 53-45-40 dB respectively.
- Most countries adopt national standards for ambient noise and specific sources.
- Standards for workers address maximum noise exposure limits, use of PPE.
Additional Tools:
- Noise analyzers apply FFT algorithms to measure noise frequencies and spectra.
- Dosemeters assess individuals noise exposure over time for monitoring compliance.
- Sound barriers, insulation kits help validate effectiveness of noise control solutions. Noise Control
- Noise control can be implemented at the source, along the transmission path, or at the receiver end.
- The best approach involves a combination of measures tailored to each specific situation.
Noise control at the source:
- Designing and using quieter vehicles, machines and equipment powered by electric motors instead of combustion engines
- Installing mufflers, soundproof enclosures and acoustic dampening lining for noisy vehicles, industrial machinery and construction equipment
- Ensuring proper maintenance and lubrication of parts to minimize mechanical noise
- Establishing routine inspection and maintenance schedules to fix potential issues early
Noise control along transmission path:
- Planting trees, shrubs and constructing earth beams along highways, rail lines and near industrial areas to absorb noise
- Installing acoustic barriers like sound walls, and using sound absorbing materials in wall and duct linings
- Conducting noise mapping to identify focus areas and route traffic away from residential zones where possible Noise control at receiver end:
- Using earplugs, earmuffs, noise-cancelling headphones and protective gear for workers and residents
- Incorporating sound insulating features in building designs like double glazed windows, acoustic panels and soundproofed vents/pipes
- Retrofitting existing structures near noisy areas with acoustic insulation of walls, doors, ceilings and roofs
- Enforcing standards and planning regulations to minimize noise conflicts between land uses Managing noise
# Managing Indoor Sound:
Indoor environments, such as workplaces and residences, require specific attention to control noise levels.
Soundproofing:
- Mass (density/thickness) of walls, doors, floors/ceilings affects transmission loss.
- Insulation materials like fibreglass, mineral wool, porous absorbers reduce structure-borne noise.
- Seals around vents/plumbing minimize flanking noise transmission.
- Acoustic privacy is required between workstations, residential units.
Noise Control in Machinery:
- Enclosing noisy machines, duct silencers, vibration isolation reduce airborne sounds.
- Maintaining/lubricating equipment, proper alignment decreases contact noise.
- Acoustic louvers help ventilation without compromising noise attenuation.
- Assessing noise levels during equipment selection and procurement.
Absorptive Treatments:
- Soft furnishings, acoustic ceiling tiles help absorb reflected sounds for ambient noise control.
- Carpets/furniture placement avoid standing waves and increase absorption coefficient.
Standards and Compliance:
- Workplace, construction, appliance noise levels are regulated for safety and well-being.
- Metrics like NR, STC, IIC are considered in designs/retrofits. Managing Outdoor Sound :
Noise Barriers:
- Barriers of earth, concrete, panels, vegetation help attenuate road/rail traffic, construction, aircraft noise.
- Design considerations include barrier location/height, transmission loss, cost-effectiveness.
- Porous barriers may provide aesthetic appeal while maintaining sound absorption.
Urban Planning:
- Zoning regulates activity types, working hours, night limits to control noise pollution levels across land uses.
- Green buffer zones, setback distances separate sensitive areas from major noise sources.
- Transit routes, facility placements consider noise mitigation during infrastructure planning.
Standards and Compliance:
- Ambient noise standards encourage adoption of low-noise equipment, PPE and noise-reducing designs.
- Monitoring noise levels aids enforcement of regulations, especially during regulatory exceedances.
Additional Controls:
- Vehicle mufflers, speed limits reduce automobile noise at source.
- Citizens' participation in local decisions supports addressing noise concerns proactively.
- Inspection and maintenance of construction machinery upholds noise emission compliance. - The Occupational Safety and Health (Noise Exposure) Regulations 2019 (Noise Regulations) are the main legislation in Malaysia for workplace noise regulation.
- The Noise Regulations set permissible noise levels for different workplaces and activities.
- The regulations apply to all workplaces in Malaysia, except for certain exempted ones like mines and quarries.
- Permissible noise levels for workplaces are specified in Schedule 1 of the Noise Regulations.
- Employers must take measures to control noise exposure if levels exceed the permissible limits.
- Employers are required to assess noise exposure and take steps to reduce excessive noise levels.
- Hearing protection must be provided to workers exposed to noise levels above 85 dB.
- The Department of Occupational Safety and Health (DOSH) enforces the Noise Regulations.
- Breaches of the regulations can result in notices of improvement or fines.
- Other relevant laws include the Environmental Quality Act 1974 and the Town and Country Planning Act 1976.
Malaysia Law on Noise