Origins
Paris, 2003
chaleur began with an experience I lived from inside one of the populations these events harm most. In August 2003, seven years into living in Paris, I was heavily pregnant with my second child (I gave birth in the final days of the heatwave) and caring for a toddler when the heat that killed roughly 15,000 people across France settled over the city. Pregnant women and young children sit alongside the elderly among the groups public health authorities recognise as most at risk in extreme heat (French Ministry of Health, Service-Public)1, and enduring those weeks in an apartment without air conditioning, first heavily pregnant and then with a newborn and a toddler, gave me an embodied understanding of how quickly environmental heat becomes dangerous for anyone who cannot easily escape it.
What protected me was less resilience than attention. As a new mother I was surrounded by focused care, with family and friends visiting constantly, fussing over the baby, noticing if I looked unwell and ensuring I was never alone for long, and that density of attention made me far less vulnerable than my circumstances alone would suggest. The people who died in Paris that August had the opposite experience, and that contrast turned out to be the whole point. I carried the recognition with me when I moved to Sydney the following August, in 2004: that the decisive factor in who comes through such an event is rarely the hazard itself and almost always the strength of the connections around the person exposed to it.
What I took from it
The reading I did later confirmed that recognition with evidence: Richard Keller's study of the Paris deaths, built on Eric Klinenberg's account of the 1995 Chicago heatwave, found that the decisive factor in who came through was rarely the hazard itself and almost always the strength of the connections around the person exposed to it. France's own answer, a municipal register of vulnerable residents, taught me as much by its limits as its intent: it reached only people willing to be listed as vulnerable, and it worked by building the very file of sensitive health data I believed no one should have to be on. The evidence for all of this, and the limits of it, are set out on the Evidence page; how chaleur is designed around those limits is on the Privacy page.
Sydney, and the Black Summer
Moving to Australia did not leave the problem behind. Years after moving to Sydney, I lived through the 2019–20 Black Summer, when bushfire smoke blanketed the city and much of eastern Australia for weeks, and the harm fell hardest on people with cardiac and respiratory conditions. What it left me with was a question rather than a conclusion: whether the pattern so clearly documented for extreme heat, in which the socially isolated are the least likely to take protective steps in time and the least likely to be reached, holds in the same way for smoke. I have not found research that settles it, because the acute effects of smoke have not been examined through the lens of social connection the way heatwave deaths have.
Why chaleur takes this form
That unanswered question is part of why chaleur takes the form it does. The hazards differ in kind, an anticyclonic heat dome over Europe and a fire season's smoke over Australia among them, yet a single, modest technical architecture can watch the official warnings for all of them and turn any one into a prompt to the person already looking out for someone. Building chaleur to cover more than heat costs little more than building it for heat alone, and it means the app can act on the connection already known to protect people in extreme heat while creating the means to test whether the same connection helps for the hazards no one has yet studied. It does all of this without ever building the centralised file of health data that France's registers required.
The founder
About Natasha
I lead chaleur's product direction, own its privacy and security architecture, and built the current working prototype myself as a solo, pre-funded effort. My professional background is in the disciplines that decide whether an application holding sensitive health information can be trusted with it: privacy, information security, and regulatory compliance in regulated environments. Most recently I was chief information security officer of a multi-jurisdictional software company, where I designed and operated an enterprise information security management system, independently audited against ISO 27001 and SOC 2, and directed each of its successive external audit cycles. My privacy work spans the Privacy Act 1988, the GDPR and HIPAA (including advising on HIPAA requirements in a healthcare context), and rests on a BA/LLB with First Class Honours from the University of Sydney together with postgraduate degrees in international business law and European Union law.
Delivery is the other half of that background. My career in business analysis began at Accenture in Paris, and before taking my most recent security role I established and led the business-analysis practice at the same software company, leading business analysis and delivery on enterprise transformation programmes for three of the Big 4 accounting firms: multi-team delivery coordination across multi-year engagements in a heavily regulated domain, with steering-committee reporting, budget and risk management throughout.
That background is why chaleur is built around its privacy architecture rather than having one retrofitted to it; the architecture itself (what stays on the device, what never leaves it, and what must pass independent review before any real-world use) is set out on the Privacy page.
chaleur's clinical content is designed to come from clinicians. Which conditions and thresholds should raise an alert, and how to speak to a carer about someone's health, are clinical judgements, and chaleur takes them from clinical partners rather than inventing them; every piece of guidance in the prototype is held as provisional until a qualified clinician reviews and signs it. I am seeking a clinical partner to shape that content and to act as co-applicant for the grant funding that would resource the engineering effort and commission the independent security, cryptography and clinical review the product must pass before it is placed in front of a real, vulnerable person.
Connect on LinkedInReferences
- French Ministry of Health / Service-Public, "Heatwave — protect yourself and your loved ones in the heat," service-public.gouv.fr.