Smoke from wildfires burning in the interior of Amazonas state and in neighboring states pushed the air quality in Manaus, the largest city in the Brazilian Amazon, to the "hazardous" level on Saturday morning (17), the worst real-time reading among Brazilian state capitals. At around 6 a.m., the international monitoring platform IQAir recorded 441 points on the city's air quality index, with a concentration of fine particulate matter (PM2.5) of 295.9 micrograms per cubic meter (µg/m³). That is 59.2 times the World Health Organization guideline, which recommends an annual average of no more than 5 µg/m³ for the pollutant. The second most polluted capital in the ranking, Porto Velho in Rondônia, registered 65 points at the same time.
Data from Selva, the environmental monitoring system run by the Amazonas State University (UEA), confirmed the deterioration. At 6:55 a.m., all monitored points in Manaus were rated "péssimo" (very bad), the most critical band on the system's scale, which considers air quality good between 0 and 25 µg/m³. In the Coroado neighborhood, on the city's east side, the concentration reached 457.7 µg/m³, according to G1.
Conditions were even worse in the countryside. Selva recorded 750.5 µg/m³ in Maués, a town on the Maués-Açu river, and 731.1 µg/m³ in Urucurituba, along the Amazon river, at around 7:16 a.m. Autazes reached 607.3 µg/m³, Itacoatiara 475.8 µg/m³ and Manaquiri 468.5 µg/m³ in the same period.
Residents describe worst smoke episode yet
On social media, Manaus residents described a strong smell of smoke, burning eyes even indoors, difficulty breathing and reduced visibility. Several posts called Saturday the worst day in a series of smoke episodes that has hit the city for weeks. "Manaus, October 17, 2026. It is so hard to breathe, a thick smoke has spread across the whole city", one user wrote on X. There was also criticism of the authorities' response, with one resident writing that "those in government are not taking the issue as seriously as they should".
According to Agência Brasil, the smoke covering Manaus comes from fires in the interior of Amazonas and in the states of Rondônia, Pará and Mato Grosso. Particles can stay suspended for days and travel long distances on the wind, and the lack of rain in the region keeps pollutants trapped in the atmosphere. Children, the elderly, pregnant women and people with pre-existing conditions are the most vulnerable groups, because exposure worsens respiratory and cardiovascular problems.
State of emergency and federal response
On October 10, the Amazonas state government declared a state of emergency in about 36 municipalities because of the fires. On Friday (16), when Manaus was already leading the pollution ranking among capitals, the city hall suspended in-person classes in the municipal school network and UEA halted academic activities at all units, in the capital and the interior.
The Health Ministry has identified 12 municipalities that need support for their health services and sent teams from the Força Nacional do SUS, a federal unit that reinforces Brazil's public health system in crisis situations, to assess the care network alongside state and municipal authorities. The ministry is also monitoring oxygen consumption and supply capacity at health units, including the special indigenous health districts. On the firefighting front, Ibama, the federal environmental agency, said it has extinguished 303 fire hotspots in Amazonas since operations began, backed by 11 aircraft, including six Air Tractor planes and a KC-390 provided by the Defense Ministry to drop large volumes of water.