The Know Daily - Tuesday 5 May 2026

_{Read in 4m 33s ∙ Listening to Zara Larsson ∙}

The London Marathon is projected to have raised nearly £90m for charity this year, once again showing why it’s the world’s biggest one-day fundraising event. Alongside the mega total, more than 1,900 people with disabilities took part which makes it the most inclusive marathon yet. What a day 💞

💡 Light pollution

Artificial light is increasingly brightening the night sky, affecting humans and wildlife alike, but new research shows steady progress in tackling it around the world.

Tell me more.
Light pollution is essentially excess or poorly directed artificial light that disrupts natural darkness – think streetlights spilling into bedrooms or city glow washing out the stars. It might sound harmless, but it has surprisingly wide-reaching effects, with around 83% of people globally now living under light-polluted skies.

Why does it matter?
For humans, that glow can interfere with sleep cycles by disrupting melatonin production, while for wildlife it can be even more disruptive, such as confusing migrating birds, disorienting sea turtles and even changing when plants grow or bloom. In short, artificial light at night doesn’t just brighten our evenings, it reshapes ecosystems and biological rhythms in ways we’re still trying to fully understand.

So what did the new study find?
It shows that Earth’s night-time lighting is surprisingly dynamic. Globally, artificial light emissions rose by about 16% over the last decade, but that headline number hides a lot of regional variation. Rapid urbanisation has made countries like China and India brighter, while parts of Europe have actually dimmed slightly (by about 4% overall) thanks to efficiency measures and policy changes.

Why’s this happening?
Urban growth is a major driver of light pollution, as expanding cities add more roads, buildings and infrastructure that all require lighting. This doesn’t merely spread light into new areas, but often increases brightness in places that were already lit. At the same time, the rise of LEDs has made lighting much cheaper and more energy-efficient, leading to a “rebound effect” where cities simply use more light for longer periods or in more locations. However, the trend isn’t uniform everywhere. Economic slowdowns, conflicts and deliberate policy choices can all reduce lighting in certain regions.

What’s being done about it?
Light pollution is increasingly being treated as a fixable environmental issue. In France, for example, they have reduced light levels by up to 33% through policies that require streetlights to be switched off or dimmed during late-night hours. Other cities across Europe and North America are adopting “smart lighting” systems that automatically dim or adjust brightness based on traffic and footfall, rather than staying fully on all night. Urban planners are also updating lighting regulations (focusing on shielding, directionality and colour temperature) to reduce unnecessary skyglow while still maintaining safety and visibility.

Anything I can do?
Even small changes at home can add up, especially when multiplied across households.

• Switch off outdoor lights when they’re not needed

• Use motion sensors or timers for garden and security lighting

• Choose warm-coloured bulbs where possible (they also set a cosy vibe)

• Fit shielded lights that point downward, not outward or upward

• Close curtains or blinds at night to reduce indoor light spill

• Support local “dark sky” initiatives

🗳️ Local elections are taking place across the UK on Thursday, with voters heading to the polls to choose councillors and mayors.

• The bigger story: Thousands of council seats are up for grabs, alongside key mayoral contests, making this one of the biggest local election tests for all the main parties. While these votes are about local services like housing, transport and bin collections, they’re also closely watched as a snapshot of national political mood. Labour, the Conservatives, Reform UK, the Liberal Democrats and the Greens are all hoping to make gains, with results expected to shape the political narrative in the days ahead.

💊 The first malaria treatment for babies has been approved by the World Health Organization in what experts are calling “a major public-health milestone”.

🎩 The Met Gala took place last night, with stars embracing the “Fashion is Art” theme on the red carpet. But the fundraiser was not without controversy, as some protested Jeff Bezos being named the lead sponsor.

🗞️ The BBC has announced 2,000 of its news staff are to be made redundant amid cost-cutting measures under new leadership.

🎟️ A free concert held by an iconic Colombian singer drew two million people to Copacabana beach, projected to have generated $155 million for the local economy.

🏰 The Celebrity Traitors lineup has been announced with 21 familiar faces set to meet Claudia in the iconic Scottish castle.  

🔗 Last week’s most clicked: The Lake Como “dupe”, Banksy’s latest piece and London’s stinkiest flower.

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