Heat Stress Doesn't Wait for a Smartphone: Building HeatLine on AWS Serverless
Discover how HeatLine uses an AWS serverless architecture to protect vulnerable, low-tech workers from occupational heat stress through helper-assisted reporting and instant risk scoring.
Student
A worker who feels dizzy at noon on a scorching construction site shouldn't need a smartphone, a mobile data plan, or fluent English just to ask for a glass of water.
Yet, most digital reporting tools make a quiet, privileged assumption: that every frontline worker has a modern smartphone, high-speed data, and the literacy to navigate an English-heavy interface. For a daily-wage laborer with a basic feature phone, or someone who never finished school, that assumption slams the door before they can even speak.
HeatLine started from a simple, disruptive question: What if the form came to the worker, instead of the worker going to the form?
The Report Nobody Can File
Heat is one of the quietest, most lethal dangers in modern labor. It builds insidiously through a long shift, culminating in dizziness, fainting, and heat stroke. The people spending the most hours exposed to it—construction workers, delivery riders, waste collectors, street vendors, and farm laborers—often have the fewest channels to sound the alarm.
We built HeatLine around three core pillars to bridge this equity gap:
- Consent-First, Helper-Assisted Reporting: A trusted helper (a supervisor, NGO volunteer, or family member) can call the worker, ask the questions, and submit the report on their behalf. Critically, the system requires explicit confirmation that the worker agreed before anything is saved.
- Zero-Typing Interaction: No complex forms. Every input is a binary yes/no or a numerical metric (e.g., Is there clean water? Shade? A rest break? Symptoms of dizziness or fatigue?). Local temperature and humidity are dynamically pulled from environmental sensors or local forecasts.
- Universal Scoring Logic: Whether a worker logs in via a web portal, a volunteer makes a call on their behalf, or an organization audits a site, every report uses the exact same deterministic scoring model.
Anatomy of a Risk: The Scoring Engine
HeatLine deliberately avoids opaque machine learning models. When lives are on the line, transparency is non-negotiable. Responders need to know why an alert fired instantly.
We use a straightforward additive scoring matrix:
Condition | Points Added |
|---|---|
Temperature 34 to 36.9°C | +20 |
Temperature 37 to 39.9°C | +30 |
Temperature 40°C or above | +40 |
Humidity 55 to 69% | +10 |
Humidity 70% or above | +20 |
No drinking water available | +20 |
No shade or rest area | +15 |
No recent rest break | +10 |
Worker reports symptoms (dizziness, nausea) | +25 |
Risk Thresholds:
- 0–34: Low
- 35–54: Moderate
- 55–74: High
- 75+: Extreme (Triggers immediate email alert)
Symptoms weigh the heaviest because dizziness and fainting signal that heat exhaustion has already begun. Missing fundamental protections—water, shade, and rest—compounds the danger.
Imagine a construction worker in Chennai on a 41°C day with 75% humidity, zero shade, no drinking water, and active dizziness. HeatLine flags this instantly with a score of 130 (Extreme), immediately dispatching an emergency alert.
Powered by AWS Serverless
Building for social impact means keeping operational overhead and costs near zero. For small volunteer teams and resource-strapped NGOs, managing infrastructure is a non-starter. That’s why HeatLine is built entirely on a serverless AWS architecture:
- Streamlit App: Acts as the lightweight interface where helpers input field data, dispatching payload JSON over HTTPS.
- Amazon API Gateway: Serves as the secure, scalable entry point for all incoming reports.
- AWS Lambda: Executes the validation logic and runs our risk-scoring Python function serverlessly.
- Amazon DynamoDB: Stores every immutable report record, detailing its submission channel, consent status, and helper metadata.
- Amazon SNS (Simple Notification Service): Automatically triggers high-priority email alerts for High and Extreme risk scores.
Engineering Resilience
One design detail we prioritized: decoupling reporting from alerting. If an email dispatch fails due to a temporary SNS glitch, the report is still safely committed to DynamoDB, and the API returns a successful save response while noting the alert status. A transient network hiccup should never cause a worker's cry for help to vanish into the void.
Honesty in Engineering: What's Built vs. What's Next
True builder transparency means showing the seams.
- What works today: The helper-assisted web channel, serverless validation, DynamoDB storage, and automated SNS alerting.
- Current limitations: The system is currently English-only (requiring a bilingual helper to read prompts aloud), lacks user authentication layers, and relies on manual email subscriptions.
- The Amazon Connect Dream: The feature I most wanted to ship was a direct-dial IVR phone line where a worker could press 1 for yes and 2 for no while voice prompts guide them, piping touch-tones directly into our Lambda scoring engine. Because Amazon Connect wasn't provisioned on my tier, it currently lives as a robust architectural blueprint and simulation.
The Road Ahead
- Multilingual Support: Adding Tamil and Hindi language packs so prompts can be read natively in the worker's tongue.
- Direct Telephony: Integrating Amazon Connect for interactive voice response (IVR) and AWS End User Messaging for SMS-based reporting.
- Responder Dashboards: A live triage view allowing NGOs to track open High/Extreme cases from "Reported" to "In Progress" to "Resolved."
- Public Heat-Risk Maps: Visualizing hyper-local microclimate risk data in real-time.
Why It Matters
The worker who needs water the most is almost always the one least equipped to ask for it digitally.
HeatLine won't solve global climate change or systemic labor reform overnight. But it drastically lowers the friction of saving a life—turning a complex, inaccessible bureaucratic process into a quick conversation, a trusted helper, and an instant serverless alert that ensures someone on the other end is listening.
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