Week 11: Light & Noise Pollution

Describe and explain the main types & sources of light pollution in urban environments

Sky glow - Urban light caused by the scattering of artificial light in the atmosphere. Composed of upwards light & reflected off urban surfaces (e.g. traffic, streetlamps)

Glare - excessive brightness that causes visual discomfort (e.g. unshielded headlights, floodlights, streetlamps, billboards)

Light trespass - unwanted light spilling into natural or residential areas (e.g. traffic, streetlamps, signs/billboards)

Over-illumination - using more light than needed. Typically LEDs due to low cost

Describe and explain noise pollution and its sources in an urban environment

Noise pollution - the elevation of ambient sound levels due to human activity

Sources: traffic, construction, aircraft & industry

Describe the ecological & health impacts of artificial light at night (ALAN) include a case study

Disrupt circadian rhythms & melatonin production

Case study: artificial night lighting disrupted sleep in pigeons & magpies

Sleep disruption

Altered behaviour - foraging, migration, predator avoidance/increased exposure

Phenological effects (e.g. early flowering in plants, delayed dormancy)

Describe the ecological & health impacts of noise pollution

Wildlife: disrupts communication, navigation, foraging, mating behaviour, biodiversity

Humans: linked to stress, sleep disruption, cognitive impairment, heart-related issues

Explain species-specific sensitivities to light pollution

Sensitivity varies by species and wavelength; blue-rich light can strongly affect biological rhythms.

Nocturnal & crepuscular species rely on darkness to forage, mate & avoid predators - depend on scotopic (low light) vision which becomes saturated & ineffective under bright light

Birds become disorientated & cluster dangerously around bright light (9/11 tower)

Plants misread day length, shift flowering, leaf drop & seed dispersal

Explain species-specific sensitivities to noise pollution

Different animals have different hearing ranges & sensitivities.

Noise overlapping an animal’s hearing or communication frequencies can mask calls and prey/predator cues

E.g. Owls rely on subtle sound cues to survive, dolphins habitat reduction, shifting predator-prey interactions

Identify urban planning & management strategies that mitigate the ecological & human health impacts of light pollution

Minimise unnecessary lighting - reduce brightness, duration & coverage

Use warm coloured LEDs (longer wavelengths)

Install shield & downward facing fixtures to reduce light spill & sky glow

Establish ‘dark sky’ zones or light curfews in sensitive habitats

Identify urban planning & management strategies that mitigate the ecological & human health impacts of noise pollution

Noise barriers & berms - physical structure to block or deflect sound

Quieter transport infrastructure - electric vehicles, low noise tyres, rail dampeners

Soundproof architecture - double-glazed windows, insulated walls

Strategic urban planning - buffer zones, noise zoning

Green infrastructure - parks, tree belts & green roofs