An air quality alert remained in effect for the entire Chicago area Friday, with another "Air Pollution Action Day" alert declared as wildfire smoke from Canadian wildfires continues to impact parts of the Midwest.
As of early Friday morning, the Air Quality Index for Chicago was reporting a PM2.5 of 116, which ranked in the "unhealthy for sensitive groups" category and level two of six on the Environmental Protection Agency's air quality scale.
Stream NBC 5 for free, 24/7, wherever you are.
WATCH HERE
That's a 30 percent improvement from yesterday, NBC 5 Storm Team Meteorologist Kevin Jeanes said, where the PM2.5 ranked at 160, leading air quality to be in the "unhealthy" for all groups category.
Jeanes said the air quality will continue to improve Friday and going into the weekend.
"It's still hazy, but that number is lower than it was 24 hours ago," Jeanes said, noting that those with respiratory issues like asthma may continue to be affected. "A slight improvement from yesterday."
Jeanes added that wildfire smoke will continue to shift to the east, moving out of Illinois and into Michigan. As of Friday morning, the worst air quality in the country was recorded in Ann Arbor, Jeanes said.
"Tomorrow should continue to get better, and then by the weekend, it will continue to improve," Jeanes said.
Still, an air quality alert for the entire Chicago area and an "Air Pollution Action Day" alert remained in effect through midnight.
Feeling out of the loop? We'll catch you up on the news you need to know with the Chicago Catch-Up newsletter.
SIGN UP "Everyone should reduce prolonged activities or heavy exertion outdoors," the National Weather Service said. "Active children, older adults, and people with pulmonary or respiratory disease such as asthma should avoid
prolonged activities or heavy exertion outdoors."
Health experts warned the poor air quality could lead to discomfort.
"If you feel that you're outside and your eyes are burning, then that's probably an indication that the outdoor air quality is bad and it would be better to try and get indoors," said Dr. Robert Feldman, an emergency medicine attending in the E.R. at Cook County's Stroger Hospital.
According to the Illinois Environmental Protection Agency, an "Air Pollution Action Day" is declared when widespread ozone or particulate levels are at or above the "unhealthy for sensitive groups" category for multiple days.
As part of the declaration, the Illinois EPA encouraged residents to avoid filling up cars with gas until after sunset, and group errands to minimize the number of trips taken. Carpooling and use of public transit are also highly encouraged on high pollution days, the EPA said.
Temperatures Friday would be in the mid 70s, with cooler readings near the lake through Saturday. Sunday would be cooler, Jeanes said, with a chance of strong-to-severe storms.
What is the Air Quality Index?
According to officials, the Air Quality Index, or the AQI, is used by the Environmental Protection Agency to communicate to the public air quality levels, and how they can impact day-to-day life.
There are six different levels of air quality, and they’re all color-coded to illustrate changes in quality and how they impact residents.
Typically, anything above 100 is considered to be hazardous to at least some groups, and anything over 150 is considered to be “unhealthy,” posing issues to the general public.
How to find Chicago's AQI
AirNow provides a tool for residents to search their ZIP code to see what their forecasted air quality is, both in real time and for the days ahead.
For a more granular look, the website also offers information on different measurement stations around the area in real-time, allowing residents to track air quality in areas near their homes.
Early Friday morning, Chicago's AQI, with a PM2.5 of 115, was listed in the "unhealthy for sensitive groups" category.
Air Quality Index map: Track the air quality near you
A real-time, interactive map of air quality from AirNow.gov can be found below:
What is PM2.5?
According to the Environmental Protection Agency, "PM stands for particulate matter (also called particle pollution): the term for a mixture of solid particles and liquid droplets found in the air."
"Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope," the EPA states.
PM2.5 in particular involves "fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller." By comparison, the average human hair strand is about 70 micrometers in diameter, or 30 times larger than these particles.
PM2.5 is one of five major air pollutants regulated by the Clean Air Act, which also includes ground-level ozone, carbon monoxide, sulfur dioxide and nitrogen dioxide.
