Chicago: Popular weather apps spark panic by reporting dangerously hazardous AQI. Here's what really happened

Hindustan Times

24-04-2025

Various popular weather apps across Chicago sparked panic among residents by showing that the air was unsafe to breathe early Wednesday morning, April 23. Google's air quality map showed that Chicago had the worst air in the country. According to Apple's weather app, too, the Air Quality Index had climbed into the 400s. The reading was so hazardous that people felt the need to stay indoors.
All of this happened only for it to later be revealed that the reading was actually a glitch.
Madeline Blair, 24, woke up to find her Apple weather app showing such unhealthy air quality levels, and decided to skip her morning walk. Instead, she went down into her basement to retrieve her air filter.
'I live on the northwest side, and my area on the map was dark purple on the Apple radar, so I'm like, No thanks, I'm just staying inside,' Blair said, according to The New York Times.
Shocked at the air quality readings, Savannah Bhojwani, 26, who lives in Old Town, went on to text screenshots of the readings to her friends. She saw the readings in the 200s at 10 am on her Apple Weather app, and eventually watched them rise into the 400s. She initially thought the readings may be wrong, but cloudy, gray weather made it difficult for her to be certain.
When she texted the screenshots to her friends, one of them said it may be a garage fire, while another suspected a gas leak. However, none of them could find any information on the local news or from public health officials.
On social media, netizens engaged in similar conversations. Many began speculating potential causes of the hazardous air quality.
The reading came shortly after the American Lung Association issued its annual State of the Air report, ranking the Chicago area 15th worst in the nation for ozone pollution. Los Angeles was at the No. 1 spot.
However, not everyone reported the dangerous air quality levels Wednesday. The Environmental Protection Agency's AirNow, as well as PurpleAir, both popular sources for such information, showed good air quality in Chicago.
The Chicago Department of Public Health later confirmed that the air quality index in Chicago was actually at safe levels. However, it did not speculate on what may have caused the glitch.
Apple and Google use the same source for their data – BreezoMeter. The company, acquired by Google in 2022, says it uses the same sensors that AirNow and PurpleAir use. However, it also does incorporate additional data sources in determining the Air Quality Index.
When the sun had come out but the Apple weather app still showed unhealthy air, Bhojwani decided it must be a glitch. 'This is clearly inaccurate, I thought,' she said.
Blair, too, thought the same. Now it's beautiful outside — I'm about to go get coffee with a friend before going to a poetry reading,' she said just before 4 pm local time. 'So I guess you could say I'm resuming normal activities.'
Abigail Jaffe, a spokeswoman for Google, said late Wednesday that the mistakenly high readings were the fault of 'a third-party monitoring station inaccurately reporting high measurements.' Both Google and Apple's maps finally showed good air quality in Chicago by 5 pm.