Mass fainting incidents plagued factories in Cambodia in 2012. Photograph: Vireak Mai/Phnom Penh Post

A lobby group says three separate mass fainting incidents this week that took place at two Cambodian garment factories “speaks volumes” about the issue, because both workplaces have relatively good reputations for worker’s rights.

More than 140 workers fainted on Wednesday and Thursday at Kandal’s QMI factory, which manufactures garments for several brands including Adidas.

Pok Vanthat, deputy director of the Ministry of Labour’s health department, said the building had recently been painted, and the fumes were very strong. The department has since ordered the factory manager to clean the ventilation system twice a month to improve air quality.

Meanwhile, 35 women fainted on Wednesday at Kampong Speu’s Sabrina factory, which is the major Cambodian supplier for another sportswear giant – Nike.

The factory’s union representative Chhea Vinut said the cause was a combination of malnutirition, poor ventilation and a condition known as mass hysteria.

Dave Welsh, country director of the American Center for International Labor Solidarity, said it was significant that the incidents had happened at factories that were models in the industry.

In a business rife with impermanence, almost all of QMI’s employees are on permanent contracts, and Sabrina is one of the few factories that will work with an independent union.

“You’d expect it to happen at fairly substandard factories, but if it’s happening at these factories, then it shows the problem is very serious,,” Welsh said.

He said the incidents highlighted the underlying difficulties facing garment workers, including malnutrition, insufficient wages and long hours.

ACILS has been lobbying big-name brands to introduce a nutrition program for garment workers, which is hoped would reduce factory faintings.

The factory owners and Nike did not answer requests for comment.