LONDON, United Kingdom — On the morning of April 24, 2013, a group of garment workers argued with their managers outside Rana Plaza, a commercial building in Dhaka, Bangladesh, which contained a number of clothing factories. The garment workers said the structure was unsafe; that cracks in the building's concrete had appeared and were growing in size; and that they feared for their lives. The managers replied that anyone refusing to enter the building would have their wages docked, not just for that day but for the entire month. In Bangladesh, losing a month's wages can mean starvation, so the garment workers were forced to climb the stairs to their work stations, gingerly stepping around cracks in the floor.

An hour later, the eight storey building collapsed on itself, its illegally built top storeys shaken to bits by giant generators placed there to keep the factory running during frequent power cuts. Thousands of workers dropped through floors and were crushed by falling pillars and machinery. Survivors were trapped in a living grave.

The official death toll of Rana Plaza was 1,133, making it the deadliest garment factory disaster in history. Another 2,500 people were injured, many disabled permanently.

To be clear: this tragedy was not an accident. Nor were the recent deaths at Tazreen Fashions, also in Dhaka, and Ali Enterprises in Karachi, Pakistan. Rather, these horrible events were fully preventable, the likes of which trade unions and NGOs have been loudly warning against for decades.

Preventing such tragedies is not rocket science. It involves implementing basic health and safety measures and allowing the formation of trade unions which can provide workers with a collective voice.

Unless the rights of garment workers and their unions are respected, it is only a matter of time until tragedy strikes again and mires the fashion industry in mud and blood.

But in Bangladesh, trade unions are all but outlawed and the country lacks even the most minimal workplace health and safety regulations, a sorry state of affairs that's largely due to the fact that most of the country's factory owners are also members of the Bangladeshi government.

Amirul Haque Amir, president of the National Garment Workers Federation in Bangladesh (NGWF) explains: "The owners of the factories are ministers, ex-ministers, parliament members, ex-parliament members, army generals, civil bureaucrats, even university vice chancellors — this is the elite of society who have great influence over state mechanisms."

This elite has been particularly terrified of trade unions since 2010, when the NGWF won an 80 percent increase in the country's minimum wage. According to War On Want, an independent anti-poverty group, however, Bangladeshi garment workers are still only paid around £25 (about $40) per month, whereas the costs of basic household necessities are estimated to be £75 (about $120) per month.

But before anti-unionism is written off as a uniquely "Bangladeshi problem," consider that in the aftermath of the Rana Plaza disaster, the British government held talks with 20 British retailers, whilst deliberately excluding unions, a vital part of the retail industry.

Lucky, then, that trade unions have taken things into their own hands.

Horror was widespread after the watershed of Rana Plaza, as consumers grasped the grim realities behind the "Made In Bangladesh" labels on their clothes. Retailers who have admitted to using the Rana Plaza factory included Benetton, Bon Marché, Mango, Matalan, Primark and Walmart, but hundreds more companies use low-cost Bangladeshi factories, including upscale brands like Armani, Ralph Lauren, Michael Kors and Hugo Boss.

Sick of their warnings going unheeded, Uni Global Union (which is comprised of 20 million members of 900 unions across 150 countries) and IndustriALL (50 million members in 140 countries) capitalised on the outpouring of anger by serving retailers with an ultimatum. Working with NGOs and the NGWF, Uni Global Union and IndustriALL drafted the "Accord on Fire and Building Safety in Bangladesh" and told retailers: this time, you sign our deal.

It was a risky strategy. On May 13, three weeks after the disaster, the agreement had attracted just two "maybes." Media (and social media) pressure in Sweden quickly put H&M in a corner and brought them to the table, pen in hand. But many companies remained unmoved.

General secretary of Uni Global, Phil Jennings, describes a crucial step in getting the Accord signed by a wider group of retailers: "We said to our union affiliates in the retail sector, 'Pick up the phone. Everyone of you has a collective agreement, some of you are sitting on boards of directors — you get the companies to sign up.'"

In the UK, the Union of Shop, Distributive and Allied Workers (USDAW), a trade union representing retail workers, lobbied companies like Marks & Spencer and Next. "Our members are the ones that sell these clothes," explains USDAW’s head of research and economics, Fiona Wilson. "They are linked with workers in Bangladesh; they care about what happens to these people and their families."

The pressure campaign was a success. Two days later, 35 retailers had joined the Accord, which states: "The undersigned parties are committed to the goal of a safe and sustainable Bangladeshi Ready-Made Garment (RMG) industry in which no worker needs to fear fires, building collapses, or other accidents that could be prevented with reasonable health and safety measures."

Today, the document contains the signatures of an impressive 87 retailers, including Primark, New Look, the N Brown Group and, as of September 12, Sir Philip Green's Arcadia, owner of Topshop. And, crucially, it covers approximately 1,500 factories: enough to make a real difference. It is also legally binding in the case of dispute and IndustriALL and Uni Global are co-signatories.

The agreement is not without its opponents, however. Walmart and Gap have formed yet another voluntary, corporate-led initiative that has, of course, shunned union involvement. There are also UK-based retailers who still refuse to sign the Accord. Matalan, Edinburgh Woolen Mill (who own Peacocks and Jane Norman), Sports Direct (Republic), Mexx, JD Sports (who own Bench and Bank Fashion), and River Island, all find themselves to the right of Primark regarding human rights.

Fortunately, Edinburgh Woollen Mill are currently in negotiations to join the Accord and River Island have stated that they support the "principle and intent of the Accord," but are hoping for further dialogue over unresolved issues like costs and timescales. Matalan pointed to their "Ethical Sourcing Policy." The others, including Sports Direct, have declined to comment.

Even suspending disbelief and assuming that rogue retailers like Walmart and Gap want to protect workers, the model that they are following — voluntary self-inspection that excludes unions — is fundamentally flawed. Rana Plaza had twice been audited by Western brands, which, shockingly, did not identify any risks with the eight storey building. As a result 1,133 people were crushed to death.

Workplace standards must be set and enforced by the people who work in the factories.

Consider that under the Accord, garment workers can rightfully refuse to work in unsafe factories. What's more, these workers must continue to be paid until dangerous working conditions are resolved. Imagine what a difference this agreement would have made to the Rana Plaza workers who begged their managers for clemency on that fateful April morning.

Yet even with the implementation of the Accord, there is an extremely long way to go until Bangladeshi garment workers are fully protected and the country’s labour laws become consistent with international standards. Bereaved families and disabled workers from Rana Plaza and Tazreen Fashions still await compensation.

The Workers Rights Consortium (WRC), an independent labour rights monitoring organisation, estimates that it would take $3 billion spent over five years to implement decent standards in Bangladesh's 4,500 factories. To those who worry about where the money should come from, consider that the five siblings of the Walton family, which controls Walmart, each have personal fortunes of $18 billion. We could start with them dedicating just 3.5 percent of their wealth to ensure that the people who slave for them do not die horribly in the process.

Unless the rights of garment workers and their unions are universally respected, not just in Bangladesh, but across the world, it is only a matter of time until tragedy strikes again and once more mires the fashion industry in mud and blood.

Tansy E Hoskins is a political activist, writer and the author of Stitched Up: The Anti-Capitalist Book of Fashion