The article gets into that. Masks alone won’t cut it, the shops themselves lacks ventilation and water spraying to prevent dust.

Nearly half of the workers suffering silicosis in the UCLA and UCSF study said their workplaces were using water to control dust. Roughly a quarter said they always had respiratory protection. Fazio said studies have found that in many shops, dust is so thick in the air that respirators cannot filter out a sufficient amount.

Of course it all boils down to employers being too cheap to properly invest not only in the safety of their workers, but also proper wages for them:

Metzger argued that the kind of sophisticated and costly measures that would be needed to reliably protect workers cutting engineered stone are not economically plausible in an industry where immigrant workers typically labor in small shops and are often paid in cash. Engineered stone “is too dangerous to be used safely,” he said. “If there’s any industrial product that should be banned, this is the product.”