Away from the flames, millions of Australians are breathing unhealthy air this summer as smoke from the country’s disastrous wildfires clouds skies from Sydney to Canberra to Melbourne.

Canberra

Outside the Old Parliament House in Canberra this week. Narendra Shrestha/EPA, via Shutterstock

Australia’s capital, Canberra, has been blanketed by a thick haze of smoke from nearby fires for more than a week.

The city recorded its worst air quality day on Jan. 2, with readings of dangerous fine particulate pollution spiking to over 200 micrograms per cubic meter on average during the worst hour, according to Berkeley Earth, a nonprofit research group that aggregates data from air-quality monitoring sites. Readings for the day averaged nearly 100 micrograms per cubic meter, a level considered “unhealthy” under air quality standards developed by the United States Environmental Protection Agency.

Normally, air pollution in the city is low.

Air quality based on PM2.5 35 150 250 500 µg/m3 Good Unhealthy Hazardous

Source: Berkeley Earth

Southeastern Australia is experiencing one of the worst fire seasons on record, with hundreds of fires burning across the states of New South Wales and Victoria.

Fires have seared millions of acres since October, destroying more than a thousand homes and killing at least 19 people, including three volunteer firefighters.

[See where Australia’s wildfires are currently burning.]

Wildfires release air pollutants like carbon monoxide and nitrous oxide, which can harm the health of residents nearby and firefighters on the front lines. Another byproduct of burning, fine particulate pollution known as PM2.5 because particles measure less than 2.5 micrometers across, can be transported long distances.

Landing on instruments today... this is Canberra, 6pm in summer pic.twitter.com/zxFJGWyxZA — MarnieHW (@Marnie_HW) January 1, 2020

Breathing in these tiny particles can worsen asthma and other respiratory disorders, and lead to heart attack and stroke, among a slew of other health effects. High levels of PM2.5 pollution are particularly harmful to older people, the very young and people with compromised immune systems.

An elderly woman is reported to have died on Thursday after going into respiratory distress when she got off a plane at the Canberra airport.

Sydney

A barely visible Sydney Harbour Bridge last month. David Gray/Agence France-Presse — Getty Images

Smoke from fires has fouled Sydney’s air intermittently since November. The city recorded its worst air quality day last month, when fine particulate matter reached unhealthy levels. During the hour of highest pollution, PM2.5 readings hit nearly 400 micrograms per cubic meter, a level considered hazardous over 24 hours.

Air quality based on PM2.5 35 150 250 500 µg/m3 Good Unhealthy Hazardous

Source: Berkeley Earth

Hospital visits for breathing problems increased during the period, according to local officials. Stores sold out of air purifiers and protective masks as residents rushed to protect themselves against the pollution.

But dangerous air pollution “isn’t always obvious,” said Brian Oliver, a respiratory disease expert at the University of Technology Sydney. “It’s not just when the skies are hazy and you can’t see ahead of you. It’s when the skies might look clear but the levels of pollution are five to 10 times greater than normal.”

A coalition of more than 20 medical groups, including the Royal Australasian College of Physicians, which represents 25,000 doctors and trainees, issued a statement last month declaring the high levels of particulate pollution in Sydney a “public health emergency” and calling on the government to address climate change.

“The hazardous air pollution from the New South Wales bushfires is one of the ways people’s health is being harmed by climate change right now,” said Fiona Armstrong, executive director of the Climate and Health Alliance, an advocacy group in Australia.

The Intergovernmental Panel on Climate Change, a group of scientists organized by the United Nations, found that southern Australia is likely to see an increased risk of fire as the world heats up as a result of the burning of fossil fuels.

A smoky haze over Bronte Beach in the Sydney suburbs in December. Mark Kolbe/Getty Images

The Sydney Opera House shrouded in smoke last month. James D. Morgan/Getty Images

Across Australia, and Beyond

On Friday, smoke from fires in eastern Victoria had reached more than 100 miles west to Melbourne. To the east, hazy skies were reported across the Tasman Sea in New Zealand.

But air quality has been worst close to the flames.

Photographs of evacuees against orange and red skies have made the front pages of newspapers around the world and circulated on social media. Thousands of people, many wearing face masks, were evacuated from Mallacoota, a vacation destination in eastern Victoria, after fires threatened the area. (Air pollution readings are not available for the area because of sparse monitoring station coverage.)

Tens of thousands more fled ahead of the weekend as weather forecasters warned of heightened fire conditions.

“We have no capacity to contain these fires,” Rob Rogers, deputy commissioner of the New South Wales Rural Fire Service, told the Australian Broadcasting Corporation. “We just need to make sure people are not in front of them.”

Evacuees from Mallacoota, Victoria, were moved to safety by the Australian military. Shane Cameron/Agence France-Presse — Getty Images