A concerning air quality mystery has broken out in Chicago, as the city was reportedly blanketed with toxic chemicals – although not everyone is convinced that the emergency actually took place.
Air quality maps revealed an enormous cloud of hazardous air sitting over the entire Chicago metropolitan area Wednesday afternoon, with readings reaching 500 on the Air Quality Index (AQI) – the worst possible score on Google Maps.
An AQI of 500 denotes extremely hazardous air quality, where pollutant levels are at or beyond the upper limits of what monitoring systems typically measure which typically only happens during massive wildfires or volcanic eruptions.
The news comes as Chicago was just found to have some of the worst air quality in the US. Chicago specifically ranked poorly in particle pollution – which refers to tiny solid or liquid particles suspended in the air that people can breathe in.
While both Google and Apple customers received alarming messages about the apparent emergency, the news actually caused more confusion than panic.
Residents in the Chicago area took to social media Wednesday afternoon to share what their smartphones were telling them about the conditions outside – with many saying there was no emergency at all, according to their air quality trackers.
However, one person posted an image on Reddit, revealing that the AQI in Chicago had reached 405 just after noon ET.
‘How dangerous is it for me and my kid to be outside today?’ they asked.

Google Maps revealed a massive cloud of hazardous air sitting over Chicago Wednesday afternoon
Dr Vin Gupta, a pulmonologist in Washington’s Seattle area, told DailyMail.com: ‘An air quality of 500 or more is typically associated with some acute event, like wildfire smoke or smoke from a burning building. You typically don’t see those things unless there is a major acute event that has occurred.’Â
‘Usually, the worst of the immediate effects are in somebody with an illness like asthma or emphysema (where tiny air sacs in the lungs are damaged or destroyed),’Â Dr Gupta continued.
‘Heavily polluted air could cause an exacerbation like chest pain, short breathing, and may require these people to go to the hospital,’ the pulmonologist added.
One person revealed on X that they had received an air quality alert message on their phone, warning that ‘everyone is even more likely to experience serious health effects.’
Another person on X shared a message from their son, showing that Chicago’s air was inundated with both carbon monoxide and PM10 – meaning particulate matter with a diameter of 10 micrometers or smaller.
Both are toxic to humans, but they harm the body in different ways and vary in their toxicity depending on exposure levels and duration.
The readings, taken at 2pm ET, showed that Chicago was seeing carbon monoxide levels of 318 ppb (parts per billion) in their air.
While that level is relatively low in terms of outdoor air quality, the amount of fine particulate matter in the air set off alarm bells on Google Maps’ air quality tracking system.
Chicago’s reported PM10 concentration of 669 µg/m³ (micrograms per cubic meter) is extremely bad and fell into the ‘Hazardous’ category of the Air Quality Index, indicating serious health risks for everyone.
However, many on Reddit argued that both AccuWeather and IQAir had listed the city’s air quality as either ‘fair’ or ‘good.’
Conversely, air quality readings produced by Apple were also registering a major problem in the Chicago area on Wednesday.

Social media users on X shared disturbing images of what appeared to be an air quality emergency in Chicago Wednesday afternoon

Levels of fine particulate matter reportedly reached extremely hazardous levels and set off air quality alerts on mobile phones
‘Why is my iPhone weather app telling me that Chicago’s air quality is hazardous right now but other websites say otherwise?’ an X user asked.
Some commenters suspected that the extreme air quality emergency may have been nothing more than a glitch in the software.
IQAir noted that there were only a handful of small fires being reported on in the area Wednesday, but nothing large enough to cause an environmental emergency.
Tragically, one firefighter did die while battling a blaze on Chicago’s west side.
Dr Juanita Mora, a physician with the American Lung Association, said that it was not unusual for Chicago to have air quality alerts — adding that smog from wildfires in other areas of the country often gets pulled to the area by the wind.
Currently, first responders in New Jersey are battling a massive wildfire that has burned down over 11,000 acres.
Speaking to DailyMail.com from the city’s north side, she said she couldn’t see any smog in the air Wednesday — but it was not unusual for there to be air quality warnings even when the air was clear.
The doctor noted that she’d received five alerts on her phone over air quality in the city this year alone.
‘We might not be able to see it in the air, but that’s why I always tell my patients to check the air quality readings,’Â Dr Mora explained.
Dr Mora also warned that the reports of PM10 skyrocketing were particularly alarming.Â
‘The particles causing air pollution are one-tenth of a diameter and they enter very easily through the nose and mouth and go straight to the lungs. Once there, they can cause asthma exacerbations and coughs in adults,’ she said.
To protect health, the doctor recommended closing doors and windows during bad air quality days and using air purifiers in the home.

Chicago recently received some of the poorest grades in the US for air quality. Some areas of Illinois received an ‘F’ grade for their extremely bad ozone pollution
Chicago is known for poor air quality. The American Lung Association’s newly released State of the Air report lists the windy city as 15th overall for levels of smog, worse than its ranking in the last two yearly reports, in which it ranked 17th.
‘Years of successful cleanup of emissions from transportation, energy generation and industrial processes have contributed to falling ozone levels across much of the country since … 2000,’ according to the report, which analyzed 2023 air quality data collected by the Environmental Protection Agency.
‘Unfortunately, as was shown in 2023, one bad fire season has the potential to offset that progress, at least temporarily, creating new challenges for air pollution control efforts and putting the health of the communities affected at increased risk.’Â
The state of Illinois overall saw one of the highest increases in ozone pollution between the 2020-2022 and 2021-2023 reports.
Cook County got an ‘F’ grade for high ozone days from 2021-2023, with 52 ‘orange’ days and six ‘red’ days of extremely bad pollution.