A tectonic shift in consumer awareness of both physical and mental health is underway, thanks in large part to the global pandemic. As people become more aware of how the spaces where they spend time impact their overall well-being, things like indoor air quality (IAQ) become more of a focal point. 

Where your business operates – the actual geographic location – can play a critical role in the overall IAQ risk your business could face. Understanding the factors that can contribute to indoor air quality can help you determine what air cleaning and purification measures may be needed to counteract any potential risks in your environment. 

Ambius recently analyzed a number of government reports and publicly available industry information to determine which U.S. states face the highest risks for reduced IAQ. Do you live, work, learn, or play in an area where IAQ could be harming your health? Does your business operate in one of these states? If so, you may need to take action to protect your IAQ and those that spend time in your spaces.

The details of particulate matter

The term particulate matter, or particle pollution, is widely used in discussions of air quality. But what is it? 

The U.S. Environmental Protection Agency (EPA) states that particulate matter is “the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, 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.”

Particulate matter is typically classified into one of three categories based on the size of the particle: coarse, fine, and ultrafine. 

  • Coarse particles are large, between 2.5 and 10 microns in diameter. These are the particles that our bodies are most likely to protect us against through coughing and sneezing them out when we breathe them in. 
  • Fine particles are 2.5 microns in diameter or smaller. 
  • Ultrafine particles are less than 0.1 micron in diameter.

Scientists and health experts believe that fine and ultrafine particles pose the biggest risk to human health. These smaller particles are most likely to surpass our bodies’ natural defense systems. Breathing in particulate matter can contribute to both respiratory and cardiovascular problems.  The American Lung Association puts it quite simply: “These particles get trapped in the lungs, while the smallest are so minute that they can pass through the lungs into the bloodstream, just like the essential oxygen molecules we need to survive.”

Research has shown that even short-term exposure can be dangerous, making air cleaning and purification efforts both outside and inside even more critical.

Understanding the relationship between outdoor air quality and indoor air quality

There are many factors that contribute to indoor air quality in individual spaces. One of the most significant is outdoor air quality. Since buildings and structures must take in outdoor air to circulate, whatever is present in outdoor air is likely to be present in indoor air unless it goes through significant cleaning and purification processes. 

Outdoor air quality can be impacted by a wide range of factors, but these categories make up the major factors.

  • Transportation and vehicles: Cars, buses, trains, boats, and air transportation vehicles emit a variety of compounds that contribute to the development of smog and other pollution. Particulate matter, carbon dioxide, sulfur dioxide, and volatile organic compounds (VOCs) are all among these air contaminants. 
  • Production, manufacturing, and farming: Human industrialization and producing the food and products that humans require to live generates many things that are released into the air, including particulate matter, nitrogen oxides, carbon dioxides, pesticides, methane, and more. 
  • Climate change and environmental events: There is a symbiotic relationship between outdoor air, environmental events, and climate change, as increased air pollution accelerates climate change. As climate change continues to accelerate, weather-fueled events are contributing more to air pollution. Air quality factors in this category include ground-level ozone, wildfires, dust storms, volcanic eruptions, hurricanes, and more. 
  • Natural sources: Soil, trees, plants, and other things found in nature can release particles and compounds into the air as they grow and decay. This includes many air irritants such as allergens, mold, and spores, among others.

Other factors affecting indoor air quality

Of course, humans also have a substantial impact on IAQ within structures. In our day-to-day life, our activities and the products we use to live and make our lives more enjoyable can affect the quality of the air we breathe in those spaces. Airborne contaminants that we add include:

  • Biological pollutants (viruses, bacteria, mold)
  • Indoor particulate matter 
  • Asbestos
  • Formaldehyde
  • Lead
  • Carbon monoxide
  • Nitrogen dioxide
  • Radon
  • Pesticides
  • Smoke (wood, tobacco, stoves)
  • Volatile organic compounds given off by paint, carpeting, furnishings, and objects

The 10 states where indoor air quality is most at risk

While air quality isn’t confined to state boundaries, our analysis looked at the conditions widely present in a state to determine whether or not its residents and buildings could be exposed to indoor spaces where IAQ could face challenges. 

The Ambius analysis looked at factors such as population density, how many large and mid-size cities are present in a state, greenhouse gas emissions, number of manufacturing facilities, livestock production, acreage lost to wildfires in 2021, the percentage of the population that are smokers, as well as indoor smoking laws. In addition, Ambius considered things that could offset the risk, such as the amount of forest in a state and the awareness of poor indoor quality indicated by air purifier sales in a state. 



One of the most considerable risk points for Tennessee residents is the high percentage of state residents who are smokers combined with indoor smoking being allowed in designated areas within restaurants and no restrictions in bars. Tennessee’s manufacturing and agricultural industries also increase the IAQ risk in the state.


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North Carolina’s population density, number of cities, and high prevalence of manufacturing and agriculture put indoor air quality in the state at risk. Cigarette use is also high among adults in the state, which can lead to indoor air contamination.



Louisiana makes the top ten as the second-largest greenhouse gas producer in the country. The state has a robust manufacturing presence, with oil refineries being a predominant industry, producing 136 metric tons of greenhouse gasses annually. In addition, the state has the third-highest percentage of adult smokers, according to the U.S. Centers for Disease Control and Prevention’s State Tobacco Activities and Tracking Evaluation System, and still permits smoking in bars creating an indoor air quality risk for people who frequent and work in these businesses.



Indiana sits squarely in The Rust Belt, making it a state where manufacturing has a predominant presence, although decreased from its peak in previous decades. The state’s facilities contribute 112 metric tons of greenhouse gas emissions to the atmosphere each year according to the EPA’s FLIGHT system. When combined with the more than 7,000 manufacturing facilities in the state, it’s a cocktail of potential air contaminants that put people at risk both indoors and out.



With a low population density and sparse cities, Oklahoma may seem safe from an at-risk air quality perspective. However, as the 5th largest cattle economy in the United States, methane-producing livestock can impact air quality in the state. In addition, the Sooner state is also in the top one-third of states with the most acreage lost to wildfires. Factor in a high percentage of adult smokers – nearly 19 of every 100 adults – and limited indoor smoking restrictions and Oklahoma easily finds its way into the top 10 IAQ at-risk states.



Missouri is a consistent average performer in most risk categories, which cumulatively scores it high in our risk calculator. However, it does score significantly higher in one area: cigarette use. With 19.5 smokers out of every 100 adults and smoking only being restricted to designated areas in bars, restaurants, and private workplaces, indoor air quality may suffer in both private homes and businesses.



The tenth most densely populated state in the union and a popular tourist destination, Florida faces plenty of increased air quality risk from vehicular and port traffic, city life, and human activity. In fact, with 5 large cities (population of 250,000+) and 17 mid-sized cities (population of 100,000 – 249,999), only California and Texas, the country’s two largest states, have more cities. While at 65,758 square miles, Florida is the 22nd largest state and the third-largest greenhouse gas emitter on the EPA’s FLIGHT system, producing 120 metric tons annually.



Although it is not a leading livestock producer, the number of cattle produced per square mile in Kentucky put it at risk for methane emissions. At nearly 50 cattle per square mile, only six states can claim a higher number. Like Missouri and Oklahoma, Kentucky faces significantly increased risk from cigarette use, with 23.6 out of every 100 adults being a smoker – only West Virginia scores higher in this area with a 23.8. Kentucky also has no laws prohibiting indoor smoking, increasing the risk to anyone who spends time in a building where indoor smoking takes place. 



Although California is known for its healthy lifestyle, The Golden State consistently ranks among the worst air quality in the country, thanks to its high population, vehicle traffic, and manufacturing hubs. With more large and mid-sized cities than any other state, residents of the state face a barrage of air quality risks when indoors. The state also claims the top 3 spots on the American Lung Association’s Most Polluted Cities List in Ozone and Year-Round Particle Pollution. The propensity for wildfires in the state significantly increases the risk to air quality, as well. In 2021, California suffered the most wildfire damage: more than 9,200 wildfires destroyed well over 2.2 million acres, creating serious air quality concerns for local residents and neighboring states.



Texas earns this undesirable title of the state where air quality is most at risk thanks to its eye-popping greenhouse gas emissions. At 360 metric tons annually, it more than doubles the greenhouse gasses produced by any other state, thanks in large part to the state’s massive oil and gas industry. In addition, Texas is the number one cattle-producing state in the country, significantly increasing the risk from natural methane emissions. The Lone Star also ranks in the top ten for the amount of acreage lost to wildfires in 2021, increasing the exposure its residents face from wildfire smoke and particulate matter.

What you can do now

Don’t despair if your state is on this list. Awareness of the problem is half the battle. If you live or work in one of these states, you can take action now to help improve indoor air quality by implementing air hygiene measures, such as VIRUSKILLER™ from Ambius. Ensure your HVAC or air regulation systems have appropriate filtration in place and consider additional air cleaning technologies such as the use of UV-C light to neutralize contaminants. 

To learn more about the IAQ and different types of air cleaning and purification technologies, download these Ambius Resources:

If you’re concerned about indoor air quality in your business, an Ambius representative would be happy to help you determine the best air purification solutions to use as part of a smarter, healthier space strategy. Connect with us today to speak with a design expert.