The Guardian

Scientists tested nine different masks bought from Beijing, with variable results

We are all familiar with images of Beijing citizens wearing masks, but do they work? Scientists from Edinburgh’s Institute for Occupational Medicine tested nine different masks bought from Beijing shops. Generally, the filter in each mask worked well, the best stopped over 99% of the particle pollution and the worst stopped 70% to 80%. Next, volunteers wore the masks in a test chamber filled with diesel exhaust. Pollution inside the mask was measured as they walked, nodded and talked. One mask stopped 90% of the particle pollution while others offered almost no protection. The tightness of fit was crucial. Facial hair prevents a good seal and the fit also depends on the shape of the user’s face. If it fits well then breathing through a mask is not easy. Wearing a mask could therefore pose problems for people who already have breathing or heart difficulties. So, face masks are not the answer to our problems. Walking alongside quiet instead of busy roads can help, and generally you will experience less pollution if you walk or cycle rather than sit in a car, but the best route to clean air is not masks. We need reduce the pollution in our cities.

Development could transform how one of the world’s most common materials is made

Technology has been unveiled that could drastically cut greenhouse gas emissions from aluminium production, in a development that could transform the way one of the world’s most common materials is made.

Aluminium is used to make cars, construction materials, industrial machinery, electrical products, drinks cans, foil packaging and much more. But its production relies on processes that have changed little since the 1880s when the first smelting processes were pioneered.

Water broke through the banks of the Patel dam in Solai, northern Kenya, on Wednesday night, killing at least 38 people and forcing hundreds from their homes. Up to 40 people were rescued from the mud and taken to hospital in rescue operations conducted by the Kenya Red Cross and Nakuru county disaster management teams. But many more are feared to be trapped under debris and mud, which have submerged homes over a radius of nearly 1.2 miles

• Dozens killed and many more feared trapped after Kenya's Patel dam bursts

Photojournalist Carolina Arantes documented Brazil’s thriving cattle industry and witnessed how farmers work with genetics companies to improve the performance and profitability of their herds

Jabriel is an awesome, imposing creature. His humped figure, size and weight represent everything that is prized and revered in a bull. He is quite literally the top of the pyramid in Brazil’s vast, complicated and money-driven cattle industry.

Independent body will be backed by law requiring ministers to ‘have regard to’ core principles

A new environmental watchdog to maintain standards and hold ministers to account is to be set up under plans for a green Brexit, the government has announced.

Measures from improving air and water quality and protecting endangered species are currently overseen by the European commission and underpinned by green principles across the EU, such as “the polluter pays”.

Tanzanian government accused of putting indigenous people at risk in order to grant foreign tourists access to Serengeti wildlife

The Tanzanian government is putting foreign safari companies ahead of Maasai herding communities as environmental tensions grow on the fringes of the Serengeti national park, according to a new investigation.

Hundreds of homes have been burned and tens of thousands of people driven from ancestral land in Loliondo in the Ngorongoro district in recent years to benefit high-end tourists and a Middle Eastern royal family, says the report by the California-based thinktank the Oakland Institute.

A trip following bats along the river Cam has become one of the hottest tickets in town – and raised money for their protection

It’s an impossibly idyllic early summer evening on the Backs of Cambridge. A blackbird flutes as a man pressure-washes a table outside a hotel. Mating flies drift on the breeze, alongside a whiff of marijuana. A student lies flat on the riverbank, feet in the water.

Punting on the river Cam has stopped for the night but one boat slips into the gathering dusk: the Bat Punt Safari.

New video analysis reveals the furry thieves are looting up to half the seed put out in feeders, leaving gardeners and birds short-changed

Daylight robbery worth millions of pounds is taking place in gardens across the country with grey squirrels raiding bird feeders on a huge scale, new research has revealed.

The crimes were caught on video camera by scientists, who said grey squirrels are also known to raid birds’ nests for eggs and chicks. So people putting out food for birds are inadvertently supporting a species that harms them.

Sandy, Bedfordshire: I lean forward and the skater darts away in a series of fitful starts. A water measurer beneath my gaze stays put at the pond’s edge

A pond skater’s feet feel prey landing on the drumskin-tight surface of the water. Just how can this skater skate on thin “ice” while a fly the size of its eye falls through? Though the fly tries to drag its legs free, surface tension binds it to a sheet of elastic glue.

I lean forward and the skater darts away in a series of fitful starts. A water measurer beneath my gaze stays put at the pond’s edge. An aquatic stick insect, Hydrometra stagnorum could easily be mistaken for a strand of dark human hair. My eyes are just a handspan away, so I can observe the detail of alternating light and dark strips along its abdomen, which remind me of a ruler. However, it gets its name from the way it walks over the surface with a measured tread.

Researchers hope that insights into reproductive behaviour will help save endangered species

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A whiskery love bite on a hairy bum. It may sound like a perturbing form of foreplay but scientists believe it could help save critically endangered wombat populations in Australia’s north.

Scientists have spent two wombat breeding seasons seeking to better understand the sex lives of vulnerable southern hairy-nosed wombats, using 24-hour infrared cameras and urine samples.

Exclusive: five-year ‘enhanced clearance’ programme targets trees along 20,000 miles of track to avoid delays, according to an internal document

Network Rail is to target all “leaf fall” trees for removal alongside its tracks in a new £800m five-year programme of “enhanced clearance”, according to an internal document seen by the Guardian.

The policy document for 2019-24 emerged as the environment secretary, Michael Gove, summoned the chief executive of Network Rail for talks over their approach to environmental management following revelations about tree felling across the country by the Guardian.

Warming oceans melting Antarctic ice shelves could accelerate sea level rise

We all know intuitively that in a warmer world there will be less ice. And, since the North and South Pole regions contain lots of ice, anyone who wants to see evidence of climate change can look there.

But beyond this simplistic view, things can get pretty complex. First, it’s important to recognize that the Arctic and the Antarctic are very different places. In the Arctic, almost all the ice is floating on water – there is very little land. So, we talk about ‘sea ice’ in the north, formed from frozen sea water. On the other hand, Antarctica is a massive land mass that is covered by ice formed from snowfall (called an ‘ice sheet’). There is some floating ice around the perimeter of the land, but the vast majority of Antarctic ice is on land.

Millions of seabirds saved after remote island is officially declared rodent-free for the first time since humans arrived there more than 200 years ago

Plan to change timeline for energy use reduction puts Paris targets at risk, say MEPS

A secret UK push to weaken key EU climate laws before Brexit risks scotching the bloc’s Paris commitments, MEPs say.

The EU has committed to a 20% cut in its energy use by 2020 to be achieved by two directives, covering energy efficiency and buildings.

Wenlock Edge, Shropshire: These delicate flowers are the colour of the far blue yonder, blue remembered hills, into the blue, the beyond, a spiritual eternity

“Is love so prone to change and rot/ We are fain to rear forget-me-not/ By measure in a garden plot?” asked Christina Rossetti (A Bed of Forget-Me-Nots, 1856). The flowers of forget-me-not, Myosotis, may have been reared by measure in a garden plot here, before it was abandoned a hundred years ago and a wood of change, rot and indeed love took over.

Water, creeping, pale, tufted, Jersey, wood, alpine, field, changing and early … forget-me-nots are species of Myosotis belonging to the borage family, famous for their blue flowers; the delicate pale blue of forget-me-not is unique. Some flowers on this plant growing along the path are a brilliant white, too.

World’s biggest project to kill off invasive species to protect native wildlife is hailed a success

The world’s biggest project to eradicate a dangerous invasive species has been declared a success, as the remote island of South Georgia is now clear of the rats and mice that had devastated its wildlife for nearly 250 years.

Rats and mice were inadvertently introduced to the island, off the southern tip of South America and close to Antarctica, by ships that stopped there, usually on whaling expeditions. The effect on native bird populations was dramatic. Unused to predators, they laid their eggs on the ground or in burrows, easily accessible to the rodents.

With more electricity often generated than needed the excess could be utilised to generate the green power source

Green energy would be boosted if excess electricity from wind and solar farms was used to produce hydrogen for use in heating and other parts of the energy system, according to engineers.

Renewables were the UK’s second biggest source of electricity in the last three months of 2017, and now provide about a third of the country’s power at certain times of day.

If scandals oust Pruitt, Andrew Wheeler is an ex-coal industry lobbyist pledged to end the ‘pure hell’ of Obama regulations

If the extraordinary barrage of ethical scandals buffeting Scott Pruitt finally dislodges him as administrator of the Environmental Protection Agency, a reassuringly familiar figure to Republicans will take over and probably continue much of Pruitt’s controversial work to scale back environmental protections.

Andrew Wheeler, a former coal lobbyist, was confirmed as the EPA’s second-in-command by the Senate in April, in the face of complaints from Democrats that he will simply act as the same sort of industry mouthpiece as his boss, Pruitt.

After nearly becoming extinct in Britain, the cirl bunting has bounced back, thanks to joint efforts by RSPB and farmers

Few British birds have enjoyed such mixed fortunes as the cirl bunting, Emberiza cirlus. Discovered by my ornithological hero George Montagu in 1800, near his Devon home, it extended its range across much of southern Britain, before going into sharp retreat in the 1970s.

By 1989 there were just 120 pairs – all but two in south Devon. Then, thanks to the RSPB, and especially project officer Cath Jeffs, it bounced back. Jeffs persuaded local farmers to create the right habitat for the buntings, and today there are more than 1,000 breeding pairs.

Waltham Brooks, West Sussex: Newcomers are adding their voices to the morning chorus, alert to the emerging insects

The wind is brisk and cold, but the rain has stopped, the morning mist is dispersing and the sun is breaking through the cloud. My boots sink into mud and waterlogged grass with every step. I have to leap across submerged ditches and pools to avoid wading up to my calves through the water.