9/11 Spatial Computing Memories: What the Air Remembers

Dr. Eli Joseph and Dr. Paule Valery Joseph

Science | Sensory Memory | Spatial Computing | Digital Remembrance

What the Air Remembers

What do we lose when history is preserved primarily through images?

The morning of September 11, 2001, is remembered through photographs and television footage. The blue sky over Manhattan. The Twin Towers against the skyline. The smoke rising above the city. The streets transformed by dust and debris.

These images have become part of our collective memory. They allow generations who were not there to see what happened. Yet they capture only part of the experience.

What about the air?

What about the odors, the irritation in the nose and throat, and the environmental conditions that people experienced not only through sight and sound, but through their bodies?

One of us, Paule, had arrived in the United States from Venezuela in 2000, at seventeen years old. On September 11, she was living in New York, a city she had only recently begun to call home. Her connection to that day is personal, but it is distinct from the experiences of those who were at Ground Zero.

Years later, reflecting on September 11 through the lens of sensory science raises a question that reaches beyond any individual memory: How do we preserve the dimensions of history that photographs cannot capture?

This question brings together two fields that rarely occupy the same conversation: chemosensory science and spatial computing.

The Body as Witness

For those living, working, studying, or responding in Lower Manhattan, the aftermath of September 11 was not confined to what could be seen.

The collapse of the World Trade Center released an enormous cloud of dust, smoke, and debris. Environmental investigations subsequently identified a complex mixture of building materials, combustion products, and hazardous substances. Exposure continued for some people during the rescue, recovery, and cleanup periods [1].

The consequences were not merely sensory. They were physiological, environmental, and, for many, enduring.

Research has documented associations between World Trade Center exposures and respiratory diseases, among other health conditions. The World Trade Center Health Program continues to monitor and provide care for eligible individuals with conditions associated with those exposures [2].

Yet it is important to distinguish three experiences that are often described collectively as smell.

Odors arise when volatile molecules activate olfactory receptors. Irritation, burning, and other chemical sensations can involve the trigeminal system, which detects certain potentially harmful stimuli. Inhaled particles and gases may also cause biological harm, including when they are not consciously detected [3].

These processes can occur together, but they are not interchangeable.

A person might remember an odor, experience irritation, or inhale hazardous substances without recognizing their presence. The intensity of an odor is not a reliable measure of toxicity, nor does the absence of a detectable odor establish safety.

This distinction matters when we consider what it would mean to preserve the sensory history of September 11.

The air was not simply a background element of the disaster. For many people, it was part of their experience and, in some cases, a source of continuing illness.

When Smell Becomes Memory

Our sense of smell has a distinctive relationship with memory and emotion.

Odors can evoke autobiographical memories that feel unusually immediate, transporting us to people, places, and experiences from our past.

A familiar fragrance may recall a childhood home. The smell of food may bring back a family gathering. Other odors may become associated with difficult or frightening experiences.

Research on odor-evoked autobiographical memory helps explain these associations through the connections between olfactory processing and neural systems involved in emotion and memory [4,5].

But there is an important scientific distinction: A memory that feels vivid is not necessarily a memory that is more accurate.

Research examining recollections of first learning about September 11 found that people's confidence in their memories could remain high even as the consistency of specific details declined. This research concerned memories of receiving the news, rather than direct sensory exposure at the disaster site, and its findings should be interpreted accordingly [6].

Sensory memory presents another challenge.

With sustained exposure to an odor, perceived intensity may decrease through olfactory adaptation. This does not necessarily mean that the odor has disappeared, that exposure has ended, or that the environment has become safe [7].

Nor does it mean that the experience has been erased from memory.

Instead, it reveals a fundamental limitation of human perception: what we consciously detect at any moment is not a complete record of what our bodies have encountered.

When survivors describe the sensory atmosphere of September 11, their accounts therefore deserve careful attention. They are valuable historical testimony, even when memories are incomplete, change over time, or differ among individuals.

The goal of sensory preservation should not be to declare one recollection definitive. It should be to document the range of experiences while acknowledging the limitations of memory and measurement.

Can Spatial Computing Preserve What Photographs Cannot?

Spatial computing offers new possibilities for representing historical environments.

Through virtual and augmented reality, three-dimensional models, spatial audio, and other interactive technologies, researchers and designers can create environments that allow people to explore historical places in ways that extend beyond conventional photographs.

Could these approaches also help communicate the sensory dimensions of September 11?

The question is worth investigating, but the answer requires scientific precision.

Reconstructing the appearance of a historical location is not equivalent to reconstructing its chemical environment.

The airborne conditions around the World Trade Center varied across locations and over time. They were influenced by fires, building materials, weather, changing activities, and other factors. Historical environmental measurements and exposure assessments provide valuable evidence, but they do not constitute a complete record of what every individual inhaled or perceived [1,8].

An immersive experience might use historical records, environmental data, testimony, and carefully selected sensory representations to help communicate aspects of that history.

However, such an experience should not be presented as an exact recreation of the original atmosphere unless its accuracy has been established through appropriate validation.

Importantly, there is no need to reproduce hazardous exposures to communicate their historical significance.

The objective should be understanding, not replication of harm.

We must also distinguish a proposed technological capability from a demonstrated one. Research has explored the integration of olfactory stimuli into virtual environments, including their potential effects on presence, emotion, and memory. However, findings vary across studies, tasks, and outcome measures [9,10].

Whether adding an olfactory component improves historical understanding, emotional engagement, or retention in a September 11 remembrance experience would require direct evaluation. These outcomes cannot be assumed from the broader literature on odor-evoked memory.

Spatial computing may offer a new way to engage with sensory history. Its value will depend on what it represents, how accurately it represents it, and whether it contributes meaningfully to education and remembrance.

The Ethics of Remembering

Any effort to create an immersive representation of September 11 must begin with the people whose experiences it seeks to preserve.

Survivors, responders, residents, workers, and families may have profoundly different relationships with the event.

For some, an immersive representation could provide an opportunity for education, reflection, or recognition. For others, certain images, sounds, or sensory cues may be distressing or unwelcome.

Neither response should be presumed.

Ethical design requires meaningful consultation with affected communities, transparency about the experience, informed participation, accessibility, and the ability to stop or leave at any time.

Research on immersive technologies has identified ethical considerations involving psychological effects, autonomy, informed consent, and the responsibilities of designers and researchers [11].

These considerations become especially important when immersive technologies are used to represent traumatic historical events.

It is also necessary to avoid the assumption that emotional intensity is evidence of educational value.

A simulation that produces a powerful reaction is not necessarily historically accurate, scientifically informative, or ethically appropriate.

The distinction between remembrance and spectacle is especially important when the subject involves collective trauma.

The question is not simply whether technology can make history feel more immediate.

It is whether doing so serves a responsible purpose.

What Remains When Witnesses Are Gone?

Every generation faces the challenge of preserving experiences that future generations will know only through records.

We build memorials. We collect testimony. We preserve photographs, recordings, documents, and artifacts.

Each form of preservation contributes something valuable. Each also leaves something out.

For September 11, the visual record is extensive. The sensory record is more difficult to preserve.

We cannot assume that future generations will understand the physical experience of the environment simply by looking at images of smoke or dust.

At the same time, we should resist the temptation to promise that technology can reproduce the experience of those who were there.

No headset, digital model, or reconstructed sensory environment can fully convey another person's lived experience.

That limitation does not make new approaches to remembrance meaningless. It gives us a responsibility to approach them with humility.

Perhaps the most valuable contribution of spatial computing will not be its ability to make people feel as though they were present.

Perhaps it will be its ability to help them ask better questions about what others experienced, what was documented, what remains uncertain, and whose voices have been missing from the historical record.

Beyond the Image

September 11 was witnessed through cameras, but it was also experienced through human bodies.

The air carried sensory information and hazardous materials. The consequences of exposure continued long after the images disappeared from television screens.

Preserving this history therefore requires more than reproducing its most recognizable scenes.

It requires attention to the people who lived through it, the science that helps us understand their experiences, and the ethical boundaries of technologies that seek to represent the past.

Sensory science can contribute to that effort by explaining how chemical stimuli are detected, how odors become associated with memories, and why perception is not the same as exposure.

Spatial computing may contribute by creating new ways to explore and interpret historical environments.

Together, these fields offer a possibility—not of perfectly recreating September 11, but of broadening how we understand and preserve its history.

We cannot recreate the air that people breathed that day. But we can recognize that the air was part of their history, too.

And perhaps that is where responsible remembrance begins: not with the promise of experiencing what someone else experienced, but with the willingness to listen to what their experience can teach us.

References

[1] Lioy, P. J., Weisel, C. P., Millette, J. R., et al. (2002). Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in Lower Manhattan after the collapse of the WTC 11 September 2001. Environmental Health Perspectives, 110(7), 703–714.

[2] Wisnivesky, J. P., Teitelbaum, S. L., Todd, A. C., et al. (2011). Persistence of multiple illnesses in World Trade Center rescue and recovery workers: A cohort study. The Lancet, 378(9794), 888–897.

[3] Hummel, T., & Livermore, A. (2002). Intranasal chemosensory function of the trigeminal nerve and aspects of its relation to olfaction. International Archives of Occupational and Environmental Health, 75(5), 305–313.

[4] Herz, R. S., & Schooler, J. W. (2002). A naturalistic study of autobiographical memories evoked by olfactory and visual cues: Testing the Proustian hypothesis. The American Journal of Psychology, 115(1), 21–32.

[5] Herz, R. S. (2016). The role of odor-evoked memory in psychological and physiological health. Brain Sciences, 6(3), Article 22.

[6] Talarico, J. M., & Rubin, D. C. (2003). Confidence, not consistency, characterizes flashbulb memories. Psychological Science, 14(5), 455–461.

[7] Dalton, P. (2000). Psychophysical and behavioral characteristics of olfactory adaptation. Chemical Senses, 25(4), 487–492.

[8] Lioy, P. J., & Georgopoulos, P. (2006). The anatomy of the exposures that occurred around the World Trade Center site: 9/11 and beyond. Annals of the New York Academy of Sciences, 1076, 54–79.

[9] Spence, C. (2020). Using ambient scent to enhance well-being in the multisensory built environment. Frontiers in Psychology, 11, Article 598859.

[10] Dinh, H. Q., Walker, N., Hodges, L. F., Song, C., & Kobayashi, A. (1999). Evaluating the importance of multi-sensory input on memory and the sense of presence in virtual environments. Proceedings IEEE Virtual Reality, 222–228.

[11] Madary, M., & Metzinger, T. K. (2016). Real virtuality: A code of ethical conduct. Recommendations for good scientific practice and the consumers of VR-technology. Frontiers in Robotics and AI, 3, Article 3.