Air quality in Indiana

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

Last update at (local time)


Real-time Indiana
Most polluted city ranking

#cityUS AQI
1 Newburgh


2 Mount Vernon


3 Evansville


4 Rockport


5 Jasper


6 Bloomfield


7 Terre Haute


8 Dale


9 Ferdinand


10 Bedford


(local time)



88 Stations operated by

61 Contributors

Join the movement!

Get a monitor and contributor to air quality data in your city.

Find out more about contributors and data sources


Real-time Indiana
Cleanest city ranking

#cityUS AQI
1 Anderson


2 Warren Park


3 Ogden Dunes


4 Crown Point


5 Gary


6 West Lafayette


7 Burns Harbor


8 Chesterton


9 Michigan City


10 Whiting


(local time)


#1 Air Quality App

Free iOS and Android air quality app

AirVisual App, Free iOS and Android air quality app
Unhealthy for sensitive groups
Very unhealthy
rectangle shape clicked to open the map in fullscreen
plus icon clicked to zoom the map in
minus icon clicked to zoom the map out

How to best protect from air pollution?

Reduce your air pollution exposure in Indiana


What is the air quality index in Indiana?

Indiana is a US state in the Midwestern United States. Its capital and largest city is Indianapolis. In 2019 it had an estimated population of 6.7 million people which ranked it as the 17th most populous. It shares land borders with four other states and borders Lake Michigan and the Ohio and Wabash Rivers.

At the start of 2021, the air quality in Indiana varied between the cleanest city of Evansville with a US AQI reading of 1 and the dirtiest city of Bloomington with a US AQI reading of 148.

Between 1970 and 2018, US gross domestic product (GDP) increased by 275 per cent, vehicle miles travelled increased by 191 per cent, energy consumption increased by 49 per cent and the US population increased by 60 per cent. During the same time period, total emissions of the six principal air pollutants dropped by 74 per cent. Overall, people are more aware now of the dangers associated with air pollution and are actively doing something about it.

Is there a strategy that can improve air quality in Indiana?

The city of Indianapolis issues what it calls Knozone Action Days during high-level ozone days as part of its Thrive Indianapolis master plan. The city uses these days to teach residents about ozone and other pollutants and what they can do to improve air quality for themselves.

The local authorities know that high levels of ozone will always be a problem in Indiana because of the relatively high natural levels due to the decomposition of decaying matter in the forests. They see the way forward as trying to eradicate the local sources of ozone, leaving just the natural source.

In a recent survey, the state of Indiana ranked 19th in the nation for ozone pollution and 45th in 24-hour particulate matter ranking.

One of the more recent innovations is all about “Carbon Capture”. This is where producers of carbon dioxide can buy certificates that are worth one ton of carbon dioxide. Indiana has over 5 million acres of forestry and many more acres of arable and farmland. This could be used to sequestrate the carbon emissions from industry.

This process involves removing it from the air and burying it underground. This carbon offset trading is becoming a very lucrative business for those who have the ability to safely contain the carbon dioxide.

On 3rd February 2021, the first part of a Bill was passed by the senate which will eventually become law and thus enable carbon trading in Indiana.

Does the air quality in Indiana differ from district to district or season to season?

Indianapolis ozone season usually runs from May to September when there are roughly 83 days with temperatures over 80°F. Temperatures over 84°F are generally required for ozone to form. Ozone levels in Indianapolis tend to peak around the afternoon when direct sunlight is at its strongest.

The increase in levels of ozone is most notable in the state’s industrial centres. In Columbus, reported ozone days rose from 111 in 2015 to 242 in 2018. The Elkhart-Goshen area rose from 96 days in 2015 to 194 days in 2018. Indianapolis also experienced an increase in the amount of yearly ozone days. It jumped from 122 in 2015 to 145 in 2018. There were two cities that did not report an increase due to the fact that their equipment is not calibrated to measure ozone.

What are the sources of air pollution in Indiana?

Ozone is considered to be a secondary air pollutant for its property of being formed from primary pollutants reacting in sunlight. Indiana emissions from vehicles, fuel combustion, industrial processes, and fires all contribute to the cities levels of nitrogen dioxide (NO2) and volatile organic compounds (VOC’s), the two precursor pollutants necessary for ozone formation. It is said that vehicle emissions are responsible for between 60 to 70 per cent of the nitrogen dioxide levels in the county.

In the United States, the oil and gas industry discharges millions of tons of air pollutants into the air each year. This mix of pollutants includes methane, a very potent climate pollutant, and enormous amounts of toxic air contaminants and other chemicals that cause ozone smog pollution. Toxic air pollutants may cause cancer and other diseases, whilst ozone smog can cause a variety of health problems, such as asthma attacks and worsening the effects of bronchitis and emphysema.

Can the quality of air in Indiana be improved?

Since early 2017, Indiana has introduced a raft of measures that are all designed to improve its commitment to cleaner air. They cancelled the requirement for oil and gas producers to report methane emissions. They also stopped requiring authorities to monitor vehicle exhaust fumes on federal roads. They changed the rules on how refineries monitor air pollution in their neighbourhoods and withdrawn guidance to federal agencies to include greenhouse gas emissions in environmental reviews.

The main reason behind these changes is that in Indiana, the state is prohibited from adopting a rule or regulation that is more stringent than corresponding federal laws.

An introduction to air pollution in Indiana?

Indiana has a long-standing reputation as a polluted county. Most residents are dependent on their private cars which has historically lead to a poor public transportation system as it was always under-used. Add to this the large coal-fired power stations in the south west of the county. Their pollution is carried away by easterly winds where it pollutes the rest of the state and even beyond.

How is the air pollution level in Indiana measured?

There are five main pollutants measured when looking at standard air quality. These are ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide and Particulate Matter (PM2.5 and PM10).

The Environmental Protection Society has over 800 air pollution monitors distributed around the state to give an accurate indication as to the condition of the air.

Combustible gases (carbon dioxide and methane, for example) are usually monitored via catalytic and infrared sensors, while for the detection of toxic gases the use of electrochemical and metal oxide semiconductor sensors (also known as MOS) is common. Their mode of operation varies depending on the type (semiconductor, infrared, ultrasonic, electrochemical or catalytic sensors), but basically, two large groups can be distinguished: devices that work by absorption, contact with gas and chemical reactions, and sensors whose operation is based on infrared or ultrasonic emissions.

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

Smog is the general term used to describe a variety of air pollutants, including ground-level ozone (the main ingredient in smog), particulate matter (PM), carbon monoxide (CO), and nitrogen oxides (NOx). The term refers to air pollution that forms when gases from many sources are released into the air and chemically react with each other due to the ultraviolet rays emitted by the sun.

The prevailing ocean breeze carries smog inland toward the mountains, where an inversion layer of warm air pushes it downward, trapping the smog close to the ground where we live and breathe.

Ground-level ozone (O3) is a colourless, odourless pollutant that is formed by a chemical reaction between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. The main sources of VOCs and NOx are mobile sources which include cars, trucks and buses plus farm equipment and construction equipment. In fact, any piece of equipment that has an internal combustion engine and that is powered by fossil fuels can emit these pollutants.

Particulate matter (PM) is the term used for a mixture of solid and liquid particles found in the air. It originates from a variety of sources including automobiles, power plants, construction activities, soil, dust, soot and from some industrial processes. Coarse particulates (PM10) are generally emitted from sources such as wind-blown dust, vehicles travelling on unpaved roads, and crushing and grinding operations. Fine particles (PM2.5) can come from the combustion of fuels (cars, power generation, industrial plants) and fugitive dust. Fine particles are formed mainly in the atmosphere from gases such as sulphur oxides, nitrogen oxide and Volatile Organic Compounds.

Carbon monoxide (CO) is a colourless and odourless gas that is a by-product of combustion produced mainly by automobiles. Burned wood, charcoal and most organic material also emit carbon monoxide.

According to medical experts, children are threatened by air pollution in several ways. First of all, they are more exposed: they breathe more air in relation to their body weight and size of their lungs and they play more outdoors, with higher respiratory rates. Secondly, children are more vulnerable: their bodies are still developing and they are more susceptible to irritations and diseases. Thirdly, because of their lower height, they easily inhale fumes from vehicles emitted at a similar height to their mouths. This is especially bad for young children in push-chairs as they are pushed through city centres at exactly the wrong height.

To protect our youth, it is a good idea for all of us to become aware of air quality, especially those who supervise children and adolescents. The advice for school officials is to avoid strenuous physical activities outdoors, such as running, playing football etc., when the air is forecast to be unhealthy. If a health precautionary notice is given during the day, teachers, coaches, and others should take immediate steps to reduce children's exposure to air pollution, such as substituting strenuous outdoor activities for activities in the gym. Teachers should talk to their students about air pollution and its health effects and incorporate air quality forecasting into the classroom routine.

Indiana air quality data attribution


Which is the most polluted city in Indiana?

Your cart is empty
IQAir Blue Banner

Connect With IQAir

Sign up for our newsletter