Authored by Dr. Ludovica Gazze, Associate Professor in Economics at the University of Warwick, supported by PuroAir, a leading provider of air purification technology.
Air quality plays a crucial role in our overall health, but the focus is often on outdoor pollution, leaving many unaware of the significant impact indoor air can have. According to the World Health Organization, air pollution is one of the most significant environmental risks to health. Yet, while society has become more aware of outdoor air quality, we often overlook the conditions inside our homes and the role air purifiers play in improving it.
In this post, I break down how air quality differs between indoor, outdoor, and filtered spaces and share insights from a pilot study conducted with PuroAir that reveals just how effectively air purifiers can reduce indoor pollution.
The Overlooked Dangers of Indoor Air Pollution
While we often associate poor air quality with outdoor environments, such as urban smog or vehicle emissions, indoor air can sometimes be just as harmful—if not more. In fact, the U.S. Environmental Protection Agency (EPA) ranks indoor air pollution among the top five environmental risks to public health.
Indoor air pollution can stem from various sources on top of outdoor pollution trickling in, including cooking fumes, cleaning agents, dust, mold, and even volatile organic compounds (VOCs) from household products like paints and furniture. Pollutants can accumulate, contributing to respiratory issues, allergies, and even long-term health problems such as cardiovascular disease.
Indoor vs. Outdoor Air Quality: A Global Perspective
Urban environments around the world face air quality challenges that are both external and internal. In Latin America, 80% of the population lives in urban areas, making indoor air quality a growing concern. Moreover, people spend 60-90% of their time indoors. Despite this, we tend to focus more on outdoor pollution, such as smog and emissions, rather than the air quality inside our homes.
People living in heavily polluted areas often feel these effects even more. Outdoor pollutants like fine particles (PM2.5) can slip into homes through windows, doors, and small gaps, adding to the pollution already inside. This issue is especially challenging for low‑ and middle‑income households, where homes are often closer to pollution sources and buildings may not be well‑sealed.
The Pilot Study: Cleaner Air, Healthier Lives
To better understand the differences between indoor, outdoor, and purified air, a pilot study was conducted in Mexico City with the goal of evaluating whether air purifiers could significantly reduce indoor pollution.
The study enrolled 56 families, half of which received PuroAir air purifiers. I measured particulate matter (PM 2.5), a common pollutant that can penetrate the respiratory system and lead to health issues over time. The study aimed to:
- Measure air quality in low- and middle-income homes.
- Test air purifiers' effectiveness in improving indoor air quality and their potential to improve health outcomes.
The Abdul Latif Jameel Poverty Action Lab (J-PAL), a global research center based at MIT, funded the study as part of their King Climate Action Initiative, which supports evidence-based policies to improve health and address climate impacts. Innovations for Poverty Action (IPA) Mexico, a nonprofit organization focused on providing practical solutions to reduce global poverty, implemented the study.
Preliminary Findings: Cleaner Air, Healthier Homes
- Indoor air was often more polluted than outdoor air: Many homes without air purifiers had higher levels of PM 2.5 indoors compared to the surrounding outdoor environment. This highlights the importance of addressing indoor air quality, especially in densely populated urban areas.
- Air purifiers made a significant difference: Homes equipped with air purifiers saw a substantial reduction in PM 2.5, with levels dropping by more than half. In some cases, indoor air quality matched or surpassed outdoor air quality in less polluted areas.
- Air purifiers can be energy-efficient: Air purifiers in automatic mode adapted to changing indoor air conditions, providing clean air while conserving energy. This made them an efficient option for maintaining healthier indoor environments without significantly increasing energy consumption.
- Healthier air may lead to better sleep and well-being: Although the study primarily focused on air quality, families with air purifiers reported feeling better overall. This has led researchers to explore whether cleaner indoor air could also contribute to improved sleep and cognitive function—a relationship that will be further examined in future studies.
The chart above depicts the difference in PM2.5 between outdoor environments, indoor (control) environments vs. air purifier usage on manual mode and automatic mode.
The chart above shows the difference in sleep quality between study groups using no air purifier (control) and air purifiers on manual mode and automatic mode.
The Next Step: Understanding Air Quality’s Impact on Health
While the pilot study provided valuable insights, it also revealed the need for a larger, more comprehensive study to fully understand the impact of indoor air quality on health. In particular, future research will seek to answer critical questions, such as whether families who experience the benefits of air purifiers are more likely to invest in them long-term, and how improved air quality affects sleep quality, productivity, and overall well-being.
I am currently seeking funding for a more extensive study that will include a larger sample size and longer monitoring periods. This expanded research will delve deeper into how air purifiers can alleviate the health impacts of poor indoor air.
The Case for Cleaner Indoor Air
Indoor air quality is becoming more important as cities grow and pollution levels rise. This pilot study shows why it matters: air purifiers can noticeably cut indoor pollution and help create healthier spaces to live and work in.
Clean air, indoors and outdoors, should matter to all of us. While most people focus on outdoor pollution, the air inside our homes often has a more direct impact on our day‑to‑day health. If you’re dealing with allergens, pollution, or even sleep issues, using a high‑quality air purifier like those from PuroAir can help create a healthier, more comfortable living space.
How PuroAir is Contributing to Cleaner Air
A note on this study from our CEO:
At PuroAir, our mission is to ensure that everyone, regardless of income or location, has access to clean air. Through our cutting-edge air purification technologies, we are working to make healthier homes a reality for families worldwide.
“We’re committed to making this kind of life-changing difference, especially in underserved communities where access to clean air can be a challenge. This research reinforces our mission to ensure that everyone, regardless of income or location, can experience the benefits of healthier air,” says Robby Choueiri, CEO of PuroAir.
As a leader in the air purification industry, PuroAir supports studies like the one in Mexico City to deepen our understanding of how air quality impacts health, from reducing respiratory illnesses to improving cognitive function.
__
Ludovica Gazze is an Environmental and Health Economist dedicated to tackling some of today’s most critical societal challenges, including reducing pollution's global impact and promoting resource conservation. Utilizing large-scale administrative data and applying experimental and quasi-experimental methods, her research aims to inform and improve policy outcomes. Ludovica earned her PhD in Economics from MIT and is currently an Associate Professor of Economics at the University of Warwick. She is also an invited researcher with MIT's JPAL (KCAI and North America programs), a Research Affiliate at CEPR in the Climate Change and Environment Programme, and a Research Fellow at IZA.
4Tested to remove Fel d 1 and pollen in an ISO 17025 certified lab.