Delhi is one of the worst polluted cities in the world. Radical ideas like skyscraper-sized air purifiers are being proposed to clean the smog – can they work? There are lessons to be learned from other cities around the world about how to manage emissions. But will any city’s air ever be really clean?

(Image: A heavily polluted street in Delhi. Photo Credit: Arvind Yadav/Getty Images)

Most countries in the world have signed up to the idea that no child should work at all under a certain age – but is this the best approach? This week Nicolle, a 17 year old from Peru, has been part of a delegation of child labourers visiting the UN to ask them to rethink their ban on child labour. She’s been working since she was 8 years old, and says not only did her family need the money she earned, but working brought her status and respect. Some charities and experts working with child labourers agree that there are safe forms of child work. They say non-hazardous work can allow children to help their families, gain life skills, and even pay for the school uniforms and equipment they need to stay in education. But the UN and other former child labourers disagree, saying an outright ban is the only way to protect children from exploitation. We ask whether it’s time to rethink the ban on child labour.

Contributors include:

Benjamin Smith – Senior Officer for Child Labour, International Labour Organization Jo Boyden – Professor of International Development, Oxford University Zulema Lopez – former child labourer Kavita Ratna - Director of Advocacy and Fundraising, Concerned for Working Children

Presenter: Helena Merriman Producer: Beth Sagar-Fenton

Image: Girls collecting firewood in Eritrea, 2004 Credit: Scott Wallace/Getty Images

DNA testing is big business. Millions of people worldwide are finding out about their ancestry and genetic health traits by sending off a spit sample to one of the big consumer genetic testing companies. But what do your genes really tell you? And could genetic testing have harmful consequences for our health and for society? Four experts chart the rise of consumer genetic testing and examine the claims made and our expectations about the results.

Presenter: Helena Merriman Producer: Lucy Proctor

(image: Tube collecting saliva for dna testing of genetic markers. Photo By BSIP/UIG/Getty Images)

The story of how a line on a map becomes a hard state border that no one can cross. Korea was ruled as one Kingdom for a thousand years. They valued poetry and scholars helped rule the country. But their Kingdom was invaded by Japan. When Japan left, Russia and America raced to take their place. Amid frantic organising, a line dividing Korea in two was suggested. Who knew that line would become the front line in a war, eventually creating a hard border between two new countries?

This is a special edition that 10-14 year olds can also enjoy, but if you are not in that age bracket we hope that there’s something in it for you too. It’s a trial and we’d love to know what you think. Email [email protected] or tweet @bbctheinquiry – thanks to Niko, Christina and Sophie for your feedback. The Inquiry will be back to normal next week.

(image 2018: A North Korean student attends a class at Kang Pan Sok revolutionary school outside of Pyongyang. Credit: Ed Jones/Getty Images)

This is a special edition that younger listeners aged 10 to 14 can also enjoy. If you’re no longer in that bracket, don’t worry, The Inquiry as you know and love it will be back to normal after the next two episodes. It’s an experiment and we’d love to know what you think of it. Please email us [email protected] or tweet @bbctheinquiry.

What’s Killing Africa’s Elephants? Poachers, jewellery makers and angry farmers: the story behind the drop in elephant numbers across Africa.

Presenters: Priscilla Ngethe and Kate Lamble.

Image: African elephants (Credit: BBC)

Ever since it began, women’s sport has been beset by a fundamental question: who gets to compete as a woman? It’s a debate which is more heated now than ever. That’s because in a few months, athletics’ governing body, the International Association of Athletics Federations, will introduce controversial new rules, regulating the participation of athletes with disorders of sexual development, commonly known as intersex conditions. It’s a debate that goes far beyond sport - throwing up difficult questions about what separates men from women. In this edition of The Inquiry we plunge into this debate, which is troubling women’s sport.

Presenter: Helena Merriman Producer: Josephine Casserly

(image: Women's Athletics 200m at the 2018 Asian Games in Jakarta, Indonesia. Photo Credit: Yang Huafeng/China News/Getty Images)

Thousands of cyberattacks occur every single day. Some hackers steal credit card details or pilfer money from online bank accounts. Others cripple businesses, or even governments. As tensions mount in cyberspace, what are countries doing to strengthen their cyber power and build a hacking army? In this Inquiry, we delve into some of the world’s most intriguing cyber operations – including Iran, Russia and North Korea.

(Black Hat DEF CON cybersecurity conference in Las Vegas, Nevada USA. Photo Credit: Ann Hermes/Getty images),

It’s graduation day at the end of a religious summer school in Yemen’s Saada province. A class of young boys are off on a trip to a shrine. In a land of war, they are happy - jostling and full of energy on their school bus.

Moments later, most of the boys are dead. A Saudi-led coalition airstrike has hit their bus. The bomb that was dropped by the Saudis was made in the United States, and Saudi Arabia is the America’s single biggest customer when it comes to buying arms.

Critics argue that Donald Trump is quietly escalating America’s role in the Saudi-led war on Yemen, and many, including US Congress, have begun to question the relationship between the United States and Saudi Arabia. Will the US support Saudi Arabia no matter what? So on this week’s Inquiry we’re asking, who’s in the driving seat when it comes to the US – Saudi alliance?

Presenter: Krupa Padhy Producer: Marie Keyworth Researcher: Dearbhail Starr

(Photo: U.S. President Trump meets Crown Prince of Saudi Arabia Al Saud, (c) Getty Images)

The year 2030 was set by the UN as the world's deadline for halting the spread of HIV, stopping Aids deaths, and having the first generation since 1980 born and raised completely free from infection.

But at last month’s 22nd International Aids conference the mood was less optimistic. Deaths from the disease, having stabilised, are now beginning to increase, with some people fearing the disease is now poised to add massively to its global death toll.

As global funding for Aids decreases, and drug resistant strains of HIV rise, this week’s Inquiry asks, could we see another Aids pandemic?

(image: HIV and Aids activists in Amsterdam, Netherlands take part in the protest march Towards Zero Together. Credit: Shutterstock)

It was May 2013 when Cody Wilson went public with his 3D-printed handgun. An online video showed the crude plastic object fixed on top of a tripod. The trigger was pulled from a distance by someone pulling a long piece of string.

Since that first successful firing, 3D printed guns and the debate around them has come a long way. The design for Cody Wilson’s plastic firearm, dubbed the ‘Liberator’ has been downloaded from the internet nearly 100,000 times. The US government has tried to block its publication. But is the cat already out of the bag? Does the 3D printing revolution mean that people anywhere can print anything they want, as long as they get their hands on the right design? Can we control 3D printing?

(image: A three dimensional (3D) printer creating a product / Shutterstock)

In India, false rumours about child kidnappers, spread on WhatsApp, have prompted fearful mobs to kill innocent people. In May 2018 a video went viral. The original, a Pakistani child safety video, had been edited to show two men on a motorbike driving up to a group of children playing cricket in the street. They swoop up a small boy in a red t-shirt and drive away.

As the video spread across India people started receiving messages in their WhatsApp groups, some claiming to be from the local police, saying a gang of 250 to 300 people from outside their region had entered the area. It appealed to parents not to lose sight of their children.

Rumours like this have led to the deaths of at least 18 innocent people across India over the last few months. But what is it about this simple messaging platform - one that a fifth of the planet use every single day - that breeds intimacy, fuels emotions, and spreads fear? This week on The Inquiry we ask: Is WhatsApp fuelling vigilantism and why?

Image: A sign that says 'WhatsApp Neigbourhood Prevention'. Photo Copyright: Antal Guszlev

It’s a July morning in Ethiopia and Addisalem Hadigu, a journalist in his 50s, boards a flight to neighbouring Eritrea.

But it’s no ordinary plane. This ‘bird of peace’ is the first commercial flight to operate between the two countries since 1998, and Addisalem is flying to see his wife and two daughters – the family he hasn’t seen in 20 years.

Reunions like this are happening across Ethiopia and Eritrea, after the two countries finally agreed a peace deal and ended Africa’s longest war. But will it last? In this week’s Inquiry, we examine the ties that hold Eritrea and Ethiopia together, and the forces which could push them apart.