Readings above 150 are classified as unhealthy, while levels above 300 are considered hazardous.
The country last activated its haze subsidy scheme in 2015 when smoke from Indonesian forest fires cloaked Southeast Asia in toxic smoke for weeks, driving up illnesses and forcing school closures and flight cancellations.
In neighbouring Malaysia, schools reopened in most states on Tuesday as air quality improved slightly, but remained closed across three states, one federal territory and several districts.
Indonesia regularly battles wildfires during the dry season, but the fires have intensified this year because of El Nino, set to be one of the strongest since comparable records began four decades ago.
Experts have also pointed to slash-and-burn land-clearing practices that have changed the naturally fire-resistant landscape.