Photos: In the Amazon, millions breathe hazardous air as drought and wildfires spread through the rainforest

Thick smoke has enveloped extensive areas of the Brazilian Amazon on Thursday as the region grapples with a surge in wildfires and a historic drought.

In a city of 2 million, air quality ranked among the worst globally, leading to the suspension of college classes and the cancellation of various activities, including an international marathon.

In the first 11 days of October, Amazonas state recorded over 2,700 fires. This is already the highest number for the month since official monitoring began in 1998. Virtually all fire is human-caused, primarily for deforestation or pasture clearance.

Over the past six weeks, Manaus and other cities of Amazonas state have intermittently been blanketed by thick smoke, making it difficult to breathe. The city’s air quality index fluctuated between unhealthy and hazardous levels during the last two days, resembling the conditions in some major Asian metropolitan areas.

Over the past six weeks, Manaus and other cities of Amazonas state have intermittently been blanketed by thick smoke, making it difficult to breathe. The city’s air quality index fluctuated between unhealthy and hazardous levels during the last two days, resembling the conditions in some major Asian metropolitan areas.

On Wednesday, the city’s major universities canceled all activities, while the city’s marathon, initially scheduled for Sunday, was postponed for two months.

Normally, October marks the start of the rainy season. However, the warming of the northern Atlantic Ocean’s waters has disrupted the flow of rain clouds. Another contributing factor is El Niño, a warming of the surface waters in the equatorial Pacific Ocean, which is expected to peak in December.

Many of the Amazon’s major rivers are currently at historically low levels, disrupting navigation and isolating hundreds of riverine communities. In Tefe Lake, the heated and shallow waters likely caused the deaths of dozens of river dolphins . Most were pink dolphins, an endangered species.