SINGAPORE (AP) — Air pollution in Singapore has soared to record heights for a third consecutive day, as Indonesia prepared planes and helicopters to battle raging fires blamed for hazardous levels of smoky haze in three countries.

The blazes in peat swamp forests on Indonesia’s Sumatra island have sent massive plumes of smog across the sea to neighboring Singapore and Malaysia, both of which are growing impatient with Indonesia’s response to the problem that occurs nearly every year.

Singapore is suffering its worst haze in recorded history. Singapore’s main index for air pollution hit a measurement of 401 at midday Friday. It exceeded previous highs of 371 on Thursday and 321 on Wednesday, both of which were also record readings at the time. Those measurements are classified as “hazardous.”