One Take #4 :Indoor Air Crisis in Global Social Housing

What happens when the air inside your home is slowly making you sick? For millions of people living in social housing across developing nations, this isn't a hypothetical question—it's daily reality.

A review published in Applied Sciences reveals the shocking reality about indoor air quality in social housing throughout low and middle-income countries. The numbers are staggering: PM2.5 levels reaching 1,360 micrograms per cubic meter during cooking (90 times higher than WHO guidelines), carbon monoxide peaking at 150 parts per million, and formaldehyde concentrations nearly 5 times safe limits.

Behind these statistics are real people—predominantly women and children—suffering disproportionate exposure to harmful pollutants. The culprits? A perfect storm of low-cost building materials that off-gas chemicals, inadequate ventilation, solid fuel use for cooking and heating, and overcrowded living conditions. Even when families move from slums to public housing, pollution levels often remain dangerously high.

The research points to promising solutions through bioclimatic design strategies like cross-ventilation and proper shading, but highlights a critical reality: we can't simply transplant high-income country solutions to these contexts. Effective interventions must consider regional climate differences, cultural practices around cooking and heating, and the economic realities that drive behavior.

Perhaps most importantly, this review reminds us that indoor air quality isn't merely a technical challenge—it's fundamentally about social equity and human rights. As one researcher notes, "When we talk about the right to housing, we must include the right to healthy indoor environments."

Whether you're involved in public health, architecture, international development, or simply care about global health equity, this episode offers vital insights into an overlooked crisis affecting millions worldwide. Subscribe now and join us in exploring how we can ensure that clean air at home becomes a universal right, not a privilege.

A review of indoor air quality in social housing across low and middle income countries

Chapters

• 0:00 Welcome to Air Quality Matters
• 0:36 Social Housing Air Quality Review
• 1:07 Alarming Pollution Levels Discovered
• 2:51 Health Impacts and Retrofit Solutions
• 5:15 Research Gaps and Future Directions
• 8:41 Equity and Human Rights Concerns

Transcript

Simon: 0:00

Welcome back to Air Quality Matters and One Take One Take my take on a paper or report on air quality, ventilation and the built environment. One Take in that it's well in one take and tries to summarise something in 10 minutes or less, because who has the time to read all these? This week, I've been looking at a really important review paper. It's titled a review of indoor air quality in social housing across low and middle income countries. Links will be in the comments and show notes as usual. It was published in Applied Sciences earlier this year, in 2025. Now, this is a topic that doesn't always get the spotlight it deserves, but it affects a huge number of people globally. So what did they find and why is it something we should all be paying attention to? Well, the researchers conducted a scoping review, basically a comprehensive look at existing research, to understand the state of indoor air quality, or IAQ, in social housing, specifically within developing nations. They sifted through studies published between 2000 and 2024, so all relatively recently and ended up with 43 key papers that formed the basis for their review. Their goal was to pinpoint the main factors influencing indoor air quality in these settings, identifying where the research gaps are, and to see what opportunities there might be for making things better. And let me tell you, the findings are pretty stark. One of the headline figures from the abstract is that residents in social housing in these low and middle income countries or LMICs as the paper calls them often face, and I quote, disproportionately higher exposure to harmful pollutants. And I quote disproportionately higher exposure to harmful pollutants. We're talking about things like PM2.5, those tiny particles that can get deep into your lungs and even into your bloodstream, which they found at levels up to an astonishing 1,360 micrograms per meter cubes during cooking. To put that in perspective, the WHO guidelines for PM2.5 are around 15 micrograms over 24 hours. So yeah, orders of magnitude higher. They also found carbon monoxide, co peaking at 150 parts per million and formaldehyde levels up to nearly 5 parts per million, again frequently smashing through recommended health guidelines. So what's causing these incredibly high levels?

Simon: 2:48

The review points to several culprits the use of low-cost building materials that can off-gas harmful chemicals, often inadequate ventilation systems and sometimes just a limited public awareness about practices that could actually improve air quality, like better ventilation strategies or controlling pollution sources at their origin. And, of course, there are behaviours like indoor smoking, which is often more prevalent in low-income households and the big one in many LMICs resilience on solid fuels like wood, charcoal or dung during cooking and heating. Combine that with overcrowding, which is common in smaller homes, and you've got a recipe for poor indoor air quality. Interestingly, the paper notes that about 76% of the studies they looked at were published after 2019. This suggests a growing global awareness of just how important indoor air quality is for health, probably helped along by better measurement technologies, but also, I suspect, a heightened attention to indoor environments following COVID-19. We all spent a lot more time indoors, didn't we?

Simon: 4:00

The review categorises the studies into a few themes looking at direct measurements of pollutants, impacts on health and comfort, efforts around retrofitting and maintenance and comparative studies, and then housing conditions and socio socioeconomic factors. Across these, a few things jumped out at me, for instance, in the direct measurement studies. Beyond those cooking emissions, things like burning incense in India was a significant source of polyaromatic hydrocarbons, which aren't great for you. And it's not just in the kitchen. These pollutants often spread throughout living spaces, especially if ventilation is poor. When it comes to health and comfort, it's no surprise that this poor indoor air quality is linked to respiratory problems, asthma, tuberculosis and even mental health issues like seasonal affective disorder from lack of daylight when urban densification projects go wrong. One study in indonesia linked formaldehyde and other volatile organic compounds in newly constructed affordable apartments likely from modern building materials to multiple chemical sensitivities and respiratory problems. So new isn't always better. If the materials aren't right now, what about fixing things?

Simon: 5:20

The review looked at retrofitting and maintenance. Bioclimatic design strategies think cross ventilation using the stack effect, proper shading, all show promise and some tech like dynamic hybrid air permeable sealing systems tested in Malaysia apparently achieved a 98% reduction in particulate matter. That sounds pretty impressive, but a lot of these solutions, especially natural ventilation strategies, are very climate specific. What works in hot, humid climates might not be the answer in a colder region, and that's a key gap the paper identifies. Most research focuses on these warmer climates.

Simon: 6:02

The comparative studies were also quite revealing. Moving families from slum to public houses did in some cases reduce PM2.5 exposure, but levels often remained well above who guidelines, and sometimes even with cleaner cooking fuels. If residents kept windows closed for privacy, pollution levels indoors, especially during cooking, could still be sky high. This really underscores that occupant behavior is a massive piece of the puzzle, something the review says is still significantly understudied in the context of low-income residents in developing countries. It's not just about the building. It's about how people live in it and the cultural drivers behind those behaviours, and this ties into socioeconomic factors. Women and children in low-income households often bear the brunt of this exposure, especially from cooking. Unreliable electricity or water can force people to use polluting alternatives for lighting, and heating is a systemic issue.

Simon: 7:05

So what are the big takeaways from this review? First, indoor air quality in social housing in low to middle income countries is a major public health concern. The pollution levels are often dangerously high. Second, while there are promising solutions, particularly around adaptive architectural design and natural ventilation, many of these are context specific and lack broad empirical testing across different climates and cultures. There's a real need for cost-effective, validated interventions. Third, occupant behaviour driven by cultural norms, socio-economic pressures and awareness levels is a critical factor that needs much more research and understanding if interventions are to be truly effective. We can design the cleverest ventilation system, but if people don't use it or use it in unexpected ways, it won't achieve its goals. And fourth, there is a significant gap in research for colder climate regions in low middle income countries. The focus has largely been on warm and humid areas. The paper essentially calls for an expansion of research that really digs into these regional differences, looks closely at these socio-economic drivers and properly integrates occupant behaviour into the development of effective strategies. It's about developing indoor air quality control guidelines and interventions that are actually tailored to the realities of social housing in these diverse settings.

Simon: 8:35

One of the crucial points, I think, is that we can't just parachute in solutions from high-income countries. The challenges and contexts are often vastly different. The review highlights that improving indoor air quality in these settings isn't just a technical challenge. It's intertwined with social equity, economic development and public health. It's a comprehensive piece of work and if you're involved in housing, public health or sustainable development in low income countries, it's definitely worth a deeper dive. It paints a clear picture of the problem and, importantly, points towards where we need to focus our efforts to make a real difference to the millions of people living in these conditions. It's about ensuring that a safe and healthy environment isn't a luxury but a basic human right. Thanks for listening, as always. That's it from this week, from One Take. Don't forget to check out the sponsors in the show notes, and I'll see you again next week.