Air quality in Illinois

Air quality index (AQI) and PM2.5 air pollution in Illinois

Last update at (local time)


Real-time Illinois
Most polluted city ranking

#cityUS AQI
1The national flag of International East Saint Louis


2The national flag of International Edgewater


3The national flag of International Washington Park


4The national flag of International Aurora


5The national flag of International Albany Park


6The national flag of International Lemont


7The national flag of International Loves Park


8The national flag of International Mundelein


9The national flag of International Shorewood


10The national flag of International Lansing


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Real-time Illinois
Cleanest city ranking

#cityUS AQI
1The national flag of International Alsip


2The national flag of International Manteno


3The national flag of International Union Hill


4The national flag of International Elk Grove Village


5The national flag of International Durand


6The national flag of International DeKalb


7The national flag of International Harvard


8The national flag of International La Grange


9The national flag of International La Salle


10The national flag of International Des Plaines


(local time)


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How much air pollution is there in Illinois?

Illinois is a state in the Midwestern region of the United States. The capital of Illinois is Springfield, which is located in the central part of the state. Although today Illinois's largest population centre is in its northeast, around Chicago. In 2019, the estimated population was just over 12.6 million people.

The Port of Chicago is connected to international ports via two main routes: through the Great Lakes, via the Saint Lawrence Seaway, to the Atlantic Ocean and from the Great Lakes to the Mississippi River, via the Illinois River. The international airport of O’Hare in Chicago is consistently reported as being one of the busiest airports in the world.

Looking at the latest air quality figures published by IQAir, it can be seen that Chicago enjoyed a period of “good” quality air during 2020. The average annual figure was 11.1 µg/m³. However, for 5 months of the year, the WHO target figure of 10 µg/m³ or less was achieved. February, March, April, June and November recorded figures as being “Good” with readings between 10 and 12 µg/m³. The remaining two months of January and December saw air quality ranked as “Moderate” with figures between 12.1 and 35.4 µg/m³.

Looking back at historic figures over the past few years it seems that Chicago’s air quality is fluctuating. In 2017 the level was 6.7 µg/m³, it became slightly worse in 2018 with 9.4 µg/m³ and in 2019 it was recorded as being “Moderate” quality with 12.8 µg/m³. But then an improvement in 2020 with 11.1 µg/m³.

What are the sources of air pollution in Illinois?

Cars, trucks, and buses are a significant source of air pollution in Illinois, with air pollution from vehicles affecting everyone. Additionally, there are over 5 million people living in Cook County, which includes Chicago, all of whom experience air pollution from transportation that is amongst the worst in the nation.

How does Illinois rank in the air pollution stakes?

The American Lung Association publishes annual reports about the air quality in most states in the US. The report released in January 2019 ranked Chicago as the 18th most polluted city when considering the levels of ozone (O3). This is actually worse because during the previous year it was ranked as 22nd. The report concluded that Chicago was subject to 14 days when ozone levels were too high to be accepted. The average for the previous year was 9.8 unhealthy days!

The increase in ozone production is mainly due to an increase in the number of vehicles using the roads and the rise in temperature which produces hotter weather. The three years of 2015 - 2017 were recorded as being the hottest on record.

The other airborne pollutant which is monitored is PM2.5 which consists of soot or tiny particles that come from coal-fired power stations, vehicle emissions, wildfires and wood-burning devices. It is noteworthy that, unlike ozone, PM2.5 concentrations are on the decline due to stricter emission controls and the phasing out of some coal-fired power stations.

What can be done to lessen the risk of poor air quality in Illinois?

At the end of January 2020, a report was published that highlighted the poor air quality in and around the Chicago region. The report shows that over 9 million people in the region lived through more than 100 days of moderate air pollution or worse. Peoria, Springfield and the Metro East St. Louis region also saw more than 100 days of poor air quality in 2018. The new national statistics from 2018 used in the report represent the most recent data available.

Electricity generation and transportation are the two most polluting sectors and pollution is responsible for killing hundreds of people a year in Illinois. What is needed is a transition to clean renewable power sources such as wind and solar, whilst promoting the use of electric cars, buses and transport that eliminates pollution in Illinois.

Due to global warming, higher temperatures and more severe wildfires increase air pollution and consequently, the threat to human health.

Recommendations put forward as a result of the report include calling on officials at all levels of government to encourage the reduction of emissions from transportation, support clean renewable energy, and expand climate-friendly transportation options with more transit, cycle lanes and footpaths.

The study also calls on the federal government to strengthen ozone and particulate pollution standards, and introduce strong clean car standards.

What is the environmental policy in Illinois?

The Illinois Environmental Protection Agency (IEPA) and the Partners for Clean Air Act constantly monitor the air quality situation throughout the hot summer months and will alert the public when air pollution increases due to the heat and the sun. Usually, this means an increase in the levels of ozone.

These daily alerts are published through the local media by means of informing the residents of the possible health risks. It is especially helpful to those who suffer from pre-existing respiratory problems.

These notices alert individuals in the Chicago and surrounding northwest area, as well as the Metro East area that light winds and high temperatures may produce elevated levels of air pollution, both ozone and particulate matter, which could reach the orange level, "unhealthy air quality levels for sensitive groups".

It is hoped that individuals and businesses will be spurred to take action because of these reports.

Is Illinois adopting stricter air pollution standards?

Chicago has a history of poor air quality. As it became more industrialised, it relied on poor quality, cheap coal from southern Illinois for power and heat. It was burned in boiler rooms, locomotives, steel mills, and domestic furnaces, the ubiquitous coal created an equally ubiquitous smoke. Soot spoiled everything in the city, ruining furniture, merchandise, and even building facades due to acid rain.

As far back as 1881, Chicago saw a problem here and started to introduce legislation that would curb the use of dirty coal. Not only did it become infamous for its smoke-filled cityscape but it was regarded as somewhat of a pioneer when it came to regulations. As far back as the early 1900s saw the electrification of the Central waterfront railway line.

In 1959, the city created the Department of Air Pollution Control which set about investigating all sources of air pollution and suggested new regulations for sources that had previously been completely ignored and dismissed as being insignificant. This now included the open burning of refuse and organic matter such as dried leaves and scrap wood.

The 70s saw another milestone in cleaner air through the strict control over the major polluters at the time. This included the huge South Works steel plant. But automobiles were becoming increasingly popular as their prices became affordable to many more people. And their emissions continue to plague every major city in the world today!

By the 1990s, there was a sharp decline in heavy industry and more effective controls over automobile emissions. Together these made a huge difference to the quality of the air in Chicago to such an extent that it no longer ranked amongst the nations most polluted cities.

What are the consequences of breathing in polluted air in Illinois?

Air pollution is harmful to Illinois residents’ health and quality of life. Exposure to pollutants such as ozone and PM2.5 is associated with an increased risk of lung irritation, respiratory problems, cardiovascular disease, asthma, cancer, and even premature death. PM2.5 pollution, which can penetrate deep into the lungs, is particularly damaging. Our estimates suggest that 5 per cent of early deaths in Chicago each year can be attributed to exposure to PM2.5.

Particulate matter (PM) means solid or liquid particles of smoke, dust, and other things that are suspended in the air. When air is polluted with particulate matter, these particles enter our breathing system with the oxygen our body needs.

When the particulate matter enters the nose or mouth through the breath, the fate of each particle depends on its size - the smaller the particles, the deeper they are able to go inside the body. PM with a diameter less than 10 micrometres are included in the 'totally suspended substances' (TSP). They are so small that the hairs in the nose cannot stop them. They pass through the respiratory tract into the lungs where the metal elements present on the surface of the particles oxidise the lung cells, damage their DNA and increase the risk of causing cancer. Particle contact with the lung cells causes swelling, irritation, disturbance, and obstruction of airflow causing lung breathing difficulties such as COPD (Chronic Obstructive Pulmonary Disorder), Cystic Lung Disease, and bronchitis.

Smaller particles known as PM2.5 are even more lethal. Their diameter is only 3 per cent diameter of a human hair. In addition to increasing the risk of lung disease, PM2.5 are able to penetrate deeply into the lungs where they end up in the alveoli which are located at the base of the bronchial tubes. They make them narrow by creating inflammation in the blood vessels or by making fatty scab. This increases blood pressure or causes blood clots to form. Due to this, the flow of blood reaching the heart and brain can be stopped, which can lead to stroke or heart attack.

Illinois air quality data attribution


Which is the most polluted city in Illinois?

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