Many sportswear brands have long been criticized for working conditions in some of its factories and the heat is on again—quite literally this time. Cambodian women working in sneaker factories for Nike, Asics and Puma have been suffering mass faintings as a result the increasing temperatures.

According to The Guardian, over the past year, more than 500 employees between four sneaker factories were hospitalized. The most serious episode was, taking place over three days in November, accounted for 360 workers collapsing.

The garment industry employs nearly 600,000 workers, almost all of whom are females. The women who collapsed worked 10-hour work days, six days a week and reported feeling week. In addition to the strenuous hours, excessive temperatures inside the factories attributed to the faintings. In some instances, temperatures exceeded 37° Celsius—an equivalent to almost 99° Fahrenheit. Unlike neighboring Vietnam where temperatures aren't exceed 32° C (89.6° F) by law, Cambodia has no such regulations.

Bent Gehrt, South-east Asia field director for the Worker Rights Consortium, which monitors factories making clothing for U.S. universities said, "There is no proper investment in an adequate working environment and no investment in the living wage. If workers are fainting, it should be a clear indication you need to do something more drastic."

While brands have taken small steps to improve conditions, such as installing air conditioning units or offering tips on better employee nutrition, the occurrences have continued.

"Certain departments have small fans to cool the area, but in others the fans are only designed to remove dust from the factory, so it gets very hot,” said Norn Sophea, a representative of Collective Union of Movement of Workers

With summer in full swing and outside temperatures rising, these sportswear brands need to figure out better solutions for creating a quality work environment for employees.