Turning hazard warnings into mobilised communities

Why chaleur exists

Send the warning to the person who already worries.

Extreme heat kills the isolated first. Studies of who dies in heatwaves have repeatedly found that living alone and lacking social contact are among the strongest risk factors, and that contact during dangerous conditions is one of the few protective factors a community can influence; the people who died when the August 2003 heatwave killed roughly 15,000 across France were disproportionately those who were alone.

The established responses both miss the people they most need to reach. Warnings broadcast to everyone fail at a documented point, because the people most at risk frequently do not count themselves among them, so the warning is addressed to exactly the population least likely to act on it. Opt-in vulnerability registers (France's institutional answer after 2003) reach only those willing to enrol under the label of vulnerability, and they achieve their coverage by assembling a centralised, name-identified file of health data.

chaleur starts from the other end of the relationship. It addresses the warning to the person who already worries (an adult child, a neighbour, a friend), someone who needs no persuading that the risk is real and is close enough to act on it. Because that carer holds the details on their own device, the design delivers the protective effect of a vulnerability register without ever constructing the centralised file of health data such registers require.

Routing the warning through a carer raises an obvious question about the vulnerable person's agency, and chaleur is designed around that question rather than past it. A person can set chaleur up for themselves, holding their own profile and consenting for themselves; where a carer sets it up instead for someone able to consent, the design asks the carer to confirm the relationship and to record that agreement. The self-service path exists precisely to preserve agency; the evidence above is why the design cannot rely on it as the only path in. The harder cases, and the consent and ethics framework a pilot would need, are set out openly on the Privacy page.

What it does

Four hazards, one prompt to the person already paying attention.

chaleur reads conditions from official sources and translates them into a clear, timely prompt, leaving every judgement about a particular person to the person who knows them.

chaleur reads the climate, not the person. It can tell when the conditions around someone you care about have turned dangerous, and it says so plainly; what that person actually needs, and whether to act, stays the carer's judgement.