At Shona EPZ, a garment factory in Kenya's capital, Nairobi, the tension is inescapable. The industrious thrum of the heavy-duty sewing machines, along with the workers' chatter, normally fills the plant with a reassuring rhythm. But today every sound is tinged with uncertainty as the future of the firm is unclear because of the possible end of a key piece of US trade law.

The African Growth and Opportunity Act (Agoa), embedding in legislation a landmark trade agreement that has for 25 years given some African goods duty-free access to the US market, expires on Tuesday. However, this policy is at odds with the Trump administration's record of imposing tariffs. Envoys from various African countries have gone to the US to try to negotiate an extension.

A White House official told the BBC the administration supported a one-year extension to the programme, but this has not yet been announced. Considered the cornerstone of US-Africa economic relations, Agoa's aim was to help industrialise the continent, create employment and lift dozens of countries out of poverty. It was based on a philosophy of replacing aid with trade.

Agoa has proved very valuable for countries such as Kenya and Lesotho and the fate of thousands of workers, like 29-year-old Joan Wambui, is tied up with its future. The end of the deal could spell the end of her job.

Ms Wambui has worked at Shona EPZ, helping to sew sportswear exclusively for the American market, for just six months. In that short time, her salary has become the mainstay of her household. She supports her four-year-old daughter, two sisters in college, along with her mother.

Losing her job, she says, would affect more than just her own life. If Agoa expires, where shall we go? Ms Wambui asks in a worried tone, her hands and feet moving in time on the sewing machine as she stitches together pieces of fabric. For her, a regular wage has meant more than income. It has meant dignity and the ability to pay school fees, keep food on the table and enabled her to look forward to a better future.

It's going to hit me hard. Starting to look for a new job. In Kenya it's hard to find a job, very hard, she says as she folds the piece of fabric she has just stitched. Kenya's apparel industry has thrived under Agoa, with exports worth $470m in 2024, supporting over 66,000 jobs, predominantly held by women.

Factories like Shona EPZ have become crucial employment sources, particularly for youth. However, as the AGOA expiration approaches, uncertainty looms, leading to decreased factory outputs and diminished prospects for thousands.