TOKYO - Japan's largest clothing retailer says it will use the Higg Index tool of the Sustainable Apparel Coalition to drive environmental improvements in 70 per cent of its fabric suppliers. "Using the Higg Index, we will track and benchmark factory performance across seven different environmental themes, including emissions and wastewater, energy use and chemical use," said Yukihiro Nitta, Fast Retailing group senior vice president and sustainability director. "It means we will be able to identify which factories need support, and the best ways to make improvements."