The countries and states most concerned about indoor air quality

It’s easy to think that air pollution is only a problem for smog-filled cities, but the sad truth is that air pollution is all around, with one study finding that 99.82% of the planet’s land is exposed to unsafe levels of particulate matter 2.5 (PM2.5). Depending on where you live, your local air quality might be negatively affected by factors like local industry, heavy traffic and even wildfires.

Getting home might seem like a breath of fresh air compared to the outside, but unfortunately, there can be allergy-triggering pollutants there, too, like pet dander, dust, mold spores and harmful gasses like radon and tobacco smoke. With the average American spending 90% of their time indoors, it’s no wonder that the EPA calls indoor air pollution one of the top five environmental risks to public health.

It’s a pressing issue, but how much of a concern is indoor air quality across the U.S. and around the world? And is that concern growing at all? Guided by online searches for air purifiers — which work by removing tiny particles and odors from the air — HouseFresh went to find out. 

KEY FINDINGS

• Sweden is the most concerned country about indoor air quality: an average of 168 monthly online searches for air purifiers are made per 100k people.
• But Croatia has gotten more concerned over time: between 2018 and 2023, average monthly searches increased by +507%.
• In the U.S., Illinois is the most concerned state about indoor air quality, with an averageof 98.2 online searches for air purifiers made per month per 100k people. 
• New Hampshire has seen concerns about indoor air quality increase the most over time: between 2022 and 2023, online searches for air purifiers jumped by +29.7%.

Sweden leads as the most concerned country about indoor air quality

Our map below reveals the countries that are most concerned about indoor air quality, based on the average monthly number of online searches carried out for air purifiers per 100k of the population. Sweden comes top, with an average of 168 monthly searches made. Locals needn’t be as concerned as in other countries: outdoors, the Nordic country’s air is among the cleanest of any country in the world (based on PM2.5 levels), and looking indoors, Sweden has Europe’s lowest proportion of smokers. 

Among the other most concerned countries is Australia (138.7 searches), where bushfires happen regularly. During bushfires, locals are often advised to keep their windows and doors sealed to prevent smoke from getting into the house. But one government report cites that — depending on the age and quality of a house — these actions only offer a level of protection between 12% to 76%. Air purifiers in these homes would offer extra protection from harmful airborne particles.

The United States is not so worried about air quality (39.7 searches), despite over a third of Americans living somewhere with unhealthy levels of air pollution. 

Croatia leads in as having seen the biggest year-on-year increase (+507%) between 2018 and 2023 in searches for air purifiers. Perhaps locals are eager to control the air they can, given that Croatia’s average PM2.5 concentration in 2022 was 4.7 times the WHO’s guideline value.

Illinois residents are the most concerned about the air quality indoors

In the U.S., Illinois ranks as the most concerned state about indoor air quality, with 98.2 online searches for air purifiers carried out per month for every 100k people. It’s no wonder that air quality is a concern for Illinois residents: in 2023, the Chicago-Naperville, IL-IN-WI area ranked among the most polluted cities in the country for ozone and year-round particle pollution. 

Massachusetts comes next with 97 online searches per 100k people, where air pollution is responsible for an estimated 2,780 deaths a year. Other states in New England also place highly: Rhode Island, New Hampshire, Vermont and Connecticut. It could be that locals are reacting to last year’s localized increase in outdoor air pollution due to wildfires in Canada; wildfire smoke can enter the home through open windows and doors and ventilation units.

West Virginia — where 20% of adults smoke (more than any other state) — ranks somewhere in the middle of all the U.S. states, with an average 73.2 searches made per month for air purifiers.

When it comes to increased concern over indoor air quality, New Hampshire leads, having seen a +29.7% jump in the average monthly number of searches for air purifiers in 2023 compared to 2022. As well as the aforementioned wildfires in Canada, three in five households in the state use petroleum products as their primary heating fuel (a rate seven times higher than the national average). Burning fuel oil releases emissions like sulfur dioxide and nitrogen oxide. 

Nevada comes second (+26.4%), where (like New England) wildfires in neighboring areas — combined with ozone — are contributors to poor air quality.

Understanding the causes of poor indoor air quality

We’ve gone over some of the contributors to poor indoor air quality, but take a look at our infographic below to find out how different types of pollutants can affect different rooms in your home. 

Easy ways you can improve indoor air quality

If you’re concerned about indoor air quality, here are our five top tips to help improve the health of the air in your own home. 

1. Let fresh air in

The American Lung Association advises opening your windows for ten minutes every day to let fresh air circulate in your home (unless you live near a busy highway or pollution-emitting factory). 

2. Install a carbon monoxide alarm

Carbon monoxide is a deadly, odorless gas that is produced when fuel is burned. It can leak out of appliances like stoves, fireplaces and furnaces. Make sure you have a working carbon monoxide alarm in your home to ensure your indoor air is safe to breathe. 

3. Stop smoking

According to the Environmental Protection Agency: “There is no known safe level of exposure to secondhand tobacco smoke.” If someone in your household smokes, encourage them to give up the habit completely, cut down or smoke outside if they have to. 

4. Get a dehumidifier

Too much moisture in the home (e.g., from condensation in the bathroom) can cause mold to form, which can worsen asthma and cause respiratory issues. A dehumidifier works by extracting moisture from the air, lowering the chance of mold forming.

5. Stay on top of cleaning

Make sure you remove mold thoroughly if you find it in your home. You can make cleaning solutions using low-cost ingredients. Pet dander and dust in the air can trigger allergies, too, so try to vacuum your home at least once or twice a week (more regularly if you have pets) and keep surfaces free of dust with a microfiber cloth.

Methodology

To generate these tables, we started by translating the phrase “air purifier” into 136 different languages. 

Then, using the Ahrefs Keyword Explorer, we logged the average monthly Google search volume in 2023 for every country. We repeated this process with the DataForSEO tool to retrieve 2023 data for every U.S. State.

(Note that country search volumes were adjusted based on each country’s Google market share, sourced from gs.statcounter.com/search-engine-host-market-share/)

We then calculated the search volume per 100,000 people in every country and state to assess the relative concern for each region.

To monitor the change in indoor air quality concerns by country, we calculated the % change in monthly search volume from 2018 to 2013.

To monitor the change in indoor air quality concerns by state, we calculated the % change in monthly search volume from 2022 to 2023.

The data is correct as of January 2024.