Unhealthy indoor air threatens millions of lives. Public health advocates argue that investments in ventilation, air filtration, monitoring, and clean indoor air policies could deliver a rare triple benefit — protecting children’s health, strengthening pandemic preparedness, and creating healthier indoor environments well beyond the next global outbreak.

When Georgia Lagoudas testified in front of the Rhode Island State legislature, lawmakers in the packed, poorly ventilated room were restless and unfocused. 

The room had already exceeded near-toxic carbon dioxide levels set by the US federal occupational health agency. At 6,000 CO2 parts per million, breathing air can lead to fatigue, headaches, reduced cognitive function, and nausea. 

For Lagoudas, the argument made her push for a bill on indoor air quality in schools “easy”. 

“All I shared was this number: 6,000,” the Brown University Pandemic Center senior fellow said. “The air quality in the room not only exceeded the health-based standard of 800 parts per million, but also the US workplace safety guidelines for acute toxicity of 5,000 parts per million.”

“This was a wake-up call to turn the invisible visible,” she said.

Indoor air quality is typically calibrated to odor and comfort rather than health-based metrics. The result: “When we measure indoor air quality, it’s typically poor,” said Dr Bronwyn King, a co-founder of a coalition of indoor air advocates, Air Club, and an Australian physician and entrepreneur. 

“It’s often filled with pathogens, pollutants like wildfire smoke, vehicle emissions, particulate matter, or toxic substances like forever chemicals, or even microplastics. All of those airborne hazards are detrimental to health.”

The group’s logo, a canary, is symbolic of the “first” air pollution monitor–the canaries used in coal mines.

Lagoudas, a biosecurity expert and co-founder of Air Club, spoke at a G7 event on the sidelines of the World Health Assembly, marking the culmination of a year of growing global awareness on indoor air quality sparked by a UN General Assembly meeting in New York, which drew over 300 high-level attendees. 

It was there that Air Club, a global coalition for indoor air, launched a high-level pledge to galvanise action around indoor air quality. France and Montenegro were the first Member States to sign.

With the windows open to the Swiss mountains, the air at the indoor air quality meeting – fittingly – was crisp. Yet the reality for most buildings across the globe, far from the shores of Lake Geneva, is one of poor ventilation, air flow and contamination. 

A ‘paradox’: 90% of time spent indoors, with little protection 

People in Europe, North America, and some parts of the Middle East and East Asia spend on average 90% of their time indoors.

For the past several decades, modern buildings have become increasingly energy efficient and air tight. This prolonged time spent in poorly ventilated spaces can expose people to a host of pathogens, gases like radon and carbon dioxide, and other pollutants from mold to volatile organic compounds. 

The consequences of breathing poor quality air, King pointed out, are numerous: lung diseases from asthma, to bronchitis and pneumonia, cancer, heart attacks, brain health and cognitive declines.

“Think about how much of your everyday life is spent indoors,” said Katja Čič, a youth activist from Slovenia and International Youth Health Organization leader. “At home, school, university, or work. At the library, for groceries, cinema, shopping–all of that is indoors, and then you go back home.”

“Yet sometimes the most dangerous risk is actually trapped inside with you. Fresh air literally stops at the front door,” she said. 

Despite the risks, indoor air quality remains largely “underestimated, insufficiently regulated, and too often absent from public debate,” said Antoine Saint-Denis, director for European and International Affairs with the French Ministry of Health.

Most countries lack any form of health-based indoor air quality standards. Air Club points to five countries with the strongest, most legally-binding regulations for healthy indoor air: Belgium, South Korea, Taiwan, the UAE, and the US. About 10 other countries have some regulation or at least action plans in progress, including the UK, Germany, France, Finland, Japan, and Singapore.  

The paradox, Saint-Denis said, is the very luxury of living in more modern buildings with sealed windows, or driving cars sealed to the outside air, threatens the wellbeing of the millions lucky enough to afford them. 

“Buildings should protect us, not expose us,” Čič said. 

Indoor air pollution ranks third in the list of leading killers associated with poor air, behind ambient outdoor air pollution and cooking-related air pollution, which kills an estimated 2.9 million people each year.

A burden on school children, other vulnerable groups

Rosamund Kissi-Debrah’s daughter, Ella Roberta, was nine years old when she died from an asthma attack. Ella’s death – the first in the world to have air pollution listed as a cause – was a wake-up call to her family and her community.

“Children continue to die,” said Kissi-Debrah, whose family lived in one of the most air polluted neighborhoods of South London. 

A city that was historically smothered with industrial smog, London became ground-zero for the advocacy work of the Ella Roberta Foundation, the organisation Kissi-Debrah launched, dedicated to cleaner air for all children. Already, London has pioneered ultra-low emission zones and electric buses across the city.  

She urged policymakers in the room to read her daughter’s coroner’s report outlining steps to prevent future deaths from air pollution–and offered a searing indictment of government inaction across the world.

“There are solutions,” Kissi-Debrah argued. “But governments are reluctant. I’m not going to stand here and say it is easy. It is not, but we can do something about it.” 

Children are especially vulnerable to the effects of air pollution – not only because their lungs are still developing, but also because of prolonged exposure, up to eight hours in poorly ventilated schools. 

Several policymakers pledged to raise awareness and work with their governments on indoor air quality policies following Kissi-Debrah’s intervention. But even these advocates, like French national assembly member Emmanuel Mandon, acknowledged the steep barriers to translating the scientific reality into government action. 

“Fragmentation is a real challenge,” Mandon said. France, which was one of the first signatories of the indoor air quality pledge, has a complex administrative system “not ideal” to take swift action, like upgrading ventilation in public transportation or providing monitoring in schools. 

Yet Mandon and other French delegates remained optimistic about the issue, especially as awareness grows at the highest levels of the government. 

“This is fundamentally a question of human dignity and equity,” said Saint-Denis, pointing to the groups subjected to the worst indoor air quality and the most vulnerable to its health effects: children in poorly ventilated schools, patients in overcrowded medical facilities, workers in toxic indoor environments, prisoners, and the socioeconomically vulnerable in poor housing. 

“They are also frequently the least protected and the least able to take control of the environment that they are in,” said Jane Hulton, CEO of Coalition for Epidemic Preparedness Innovations (CEPI).

A matter of biosecurity and pandemic preparedness

An underappreciated aspect in the fight for clean indoor air is its potential to mitigate the spread of airborne pathogens. 

Around 15% of the air inhaled in an indoor space is the spent breath of another person. So with highly infectious airborne diseases such as coronaviruses, measles, or influenza, the risk of becoming sick is much higher indoors. 

The COVID-19 pandemic accelerated calls for better ventilation and monitoring, especially as buildings like schools, churches, and hospitals became hotspots for transmission. Halton called awareness of the dangers of indoor air contamination a lesson “learned too late”, recalling that transmission was “especially efficient indoors in poorly ventilated spaces”. 

Her organization, launched in the wake of the deadly 2014-16 Ebola outbreaks, aims to rapidly produce vaccines against pandemic threats. She sees improving indoor air quality as a crucial step in buying time to deploy vaccines and other medical countermeasures. 

CEPI’s 100-day mission, which would deliver a vaccine ready for manufacturing at scale within 100 days of identifying a new pandemic threat, is contingent upon preventing widespread transmission in the first 10 days, Halton said. 

“If we can’t prevent transmission in those first 10 days, we’ve exacerbated the problem.”

Biosecurity experts often draw parallels as to how the fight to eliminate water-borne pathogens came not through vaccines, but through infrastructure–water filtration and sanitation. 

“The lesson is broader than any one disease,” Halton said. “How we manage indoor air matters for preparedness, resilience, and health security across all manner of threats and risks. Taking a breath in a poorly managed indoor environment actually can amplify a biological risk.”

Progess in Montenegro, France, patchwork of US states

Lagoudas’s work led her to champion indoor air policies across the US and to collaborate with an unlikely ally – the government of Montenegro. 

The Adriatic coastal nation has begun installing air purifiers, windows that open and close, and energy efficient ventilators–machines that bring in outdoor air, filter it, and then either heat or cool it, Lagoudas explained. 

Its government has also launched efforts to monitor air quality in school buildings. While it is fairly common now to be able to check the levels of outdoor air, information of indoor air is much harder to come by.

In the past decade, advancements in small, affordable air monitors have empowered everyday citizens to track their indoor air, providing crucial real-time monitoring for health awareness. 

France, meanwhile, is at the forefront of global indoor air quality advocacy, outlining actions through their IAQ observatory and their requirements for schools and elder care facilities.

Lagoudas and the Air Club have also worked with Montenegro to advance what they term “durable policy solutions”– measures that would outlast political changes or sentiments. 

Closer to home, at least a dozen US states have passed laws to advance indoor air quality, “which is actually quite remarkable,” Lagoudas said. 

These state-level actions have typically taken the form of one of four solutions: classroom air quality monitoring, building ventilation assessment, program funding and public data sharing, and the designation of “who’s in charge” in the form of a task force or council to take action. 

This “decentralized”, patchwork approach means that very few states have implemented all four of the measures, but it nevertheless provides “it provides a great foundation” for future action, Lagoudas said. 

California requires indoor CO2 monitoring and assessments in schools receiving grants for infrastructure improvement. Connecticut also has stringent indoor air quality legislation. Other states, like Arizona, Illinois, and Massachusetts, have legislation in the books, though most states, at a bare minimum, address radon testing and carbon monoxide alarms. 

The North Star, she hopes, is federal legislation to keep school children safe across the United States – even as US public health infrastructure is “torn apart” by the Trump administration. 

The benefits to children in schools, in particular, spur indoor air quality advocates forward. 

“Healthy indoor air is actually not a niche issue,” Halton said. “It’s a core public health infrastructure issue.”

Image Credits: S. Samantaroy/HPW, Koby Levin/Outlier Media, Tim Witzdam , US EPA, Ella Roberta Foundation, Franklin Braeckman/Oceanwide Expeditions .