
It’s an unflattering number. Shocking, may be more accurate. The figure in question is the amount of years, you - the reader - have so far spent indoors.
For your average citizen living in the Global North, the math involves taking your age, and multiplying it by point nine. So, if you’re 36, that means you’ve lived 32 years indoors. If you’re 45, it’s been 40 years inside for you. An 80 year old? They have spent 72 years inside!
This formula comes from Harvard professor, and healthy buildings expert Joseph G. Allen, who has been studying indoor air for years and says that we spend 90% of our lives indoors; shuttling between homes, offices, school buildings, enclosed gyms and shopping centers and museums. “We’re an inside species,” or have become one, says Allen, on a recent podcast from the Harvard T.H. Chan School of Public Health.
Dr Joseph Allen did not stop there, revealing why it is vital to our health that we make our homes, offices and education centers places where we can breathe easy.
If you weren’t disturbed by the cumulative time spent indoors, this factoid may change your mind: “The majority of your exposure to outdoor air pollution actually occurs from the air you’re breathing indoors,” he explains, on the popular 'Better Off' podcast. "Typically, 50% of outdoor air pollution gets inside our homes and how that’s the air you’re breathing 90% of the time. Meaning that over the course of your life, you’ve probably breathed in more polluted air indoors than outdoors."
“The reality is that indoor air pollutants can be three, five, 10 times higher than outdoor air pollution, which I think surprises most people."
Joseph G. Allen
Curiously, we as humans are innately aware that something may not be right. Afterall, when we walk into our home and smell a stillness, or a musk, what do we do? We clean, we light a candle to mask an odor. Walk into a building that breathes, that’s fresh? Somewhere within us we know we prefer this space.


Many of us don't have a choice in the building we work in, which is why Allen’s research is so important from a commercial and public realm perspective - because healthy buildings made for humans should be the norm, not the exception. Likewise, everyone has the right to a healthy home, and many of the concerns Allen has are applicable in the domestic space as well.
So what is making our interior air so polluted, especially in our homes?
The answer is multifaceted, and the subject of much of Allen’s research to date. Things like off-gassing furniture, chemicals from paint, but also pollutants from everyday habits like using cleaning products, cooking, smoking, even dusting - can build up indoors and make a space 'sick'.
The origins of our buildings and homes becoming ‘sick’ goes back to the 1970s. “It was during the global energy crisis, we started tightening up our building envelope, stopped letting them breathe and ventilate, bringing in less outdoor air,” Allen continues.
In the fifty years since, architecture, design, as well as human habits, have all worked to create a perfect storm where our interior habitats are relatively unhealthy. This can manifest itself on a human level with feelings of sluggishness, headaches and poor sleep, that’s just to start. Allen’s thesis is that this era will be defined as a time when our buildings - including our homes and apartments - are actually not built for humans, certainly not their health, “as crazy as that sounds,” he says.
While you may not be able to do a radical design and architecture overhaul of your home, there are things you can do to improve the quality of the air you’re breathing inside.
The first tip, a recommendation from Allen, is to let your building breathe. “We know when you bring in more outdoor air, you reduce things like sick building syndrome,” he says. This can be as simple as opening some windows. Yet the caveat here is that homes and commercial buildings, especially in cities or areas that do suffer from moderate pollution levels, need to have high quality air filters.
Air cleaners and filters are our best defense against pollutants and air contamination from the outside and the inside - they’re especially useful if you are an asthma and allergy sufferer. Yet not all are doing the job they should do. The EPA recommends looking for air cleaning units that come with a HEPA filter which are able to remove 99 percent of fine particles.
Another tip? Choose your cleaning products wisely by looking for low VOC and green certified options. And, wherever possible, try to outfit your home with non-toxic materials and furniture.
Towards the end of the podcast, Allen sounded optimistic that change is afoot.
"If you’d asked me before the pandemic, I could have named every company and researcher focusing on healthy buildings. Since COVID, it has exploded…. my hope is that this leads to a permanent rethinking of our built environment,” he says.
While much of Allen's conversation is grounded in commercial and public real-estate, the ideas are equally true in the domestic space, with many homeowners paying more attention to indoor air quality, ventilation, and healthy home systems. After all, you’re here reading this. At the same time, the apartment construction industry is banking on ‘wellness’ and ‘green’ living, to keep people interested in high-density urban living. The times, they say, are a changin….
Regardless of the space you call home, if anything is becoming clearer it is that, with a little effort, commitment, and resources, we may be not so afraid of the years of our lives that we will spend indoors. Afterall, there are ways to have peace of mind about the inside air we breathe.



Spring Cleaning For a Healthy Home
The renewal of seasons offers the perfect opportunity to deep clean our living spaces. To eliminate the dirt and debris we can see, but even more importantly, the invisible pollutants we can't.