Which design type is this question?

It is an ioT system question. You design an air quality monitoring network and explain your choices the way you would in an interview.

Is this question asked at entry level?

It is marked Easy, so it suits engineers who are new to ioT system interviews. It is also a good warm-up before harder questions.

What should I cover first?

Start with the devices, what they send, how often and what must happen with it. Agree on scope with the interviewer before you design anything.

Can I practise it for free?

It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.

Design an air quality monitoring network

PremiumIoT systemEasy

LoRaWAN
Sensor calibration
AQI

Quick answer

This ioT system interview question asks you to design an air quality monitoring network. Aim for a design that collects data from many devices and acts on it reliably, then explain device connections, ingestion, storage and trade-offs. Interviewers want to see how you handle unreliable networks, device scale and data volume.

The problem

Design an air quality monitoring network: thousands of low-cost sensors on street poles measure dust and gases, send readings over LoRaWAN, and feed a public air quality (AQI) map and health alerts. The hard parts are cheap sensors that drift and misread in humid air, and turning noisy readings into numbers people can trust.

A city installs 5,000 solar-powered nodes and already runs 20 reference-grade stations that are accurate but expensive. Residents check a map, schools get alerts on bad days, and researchers download history.

What must an air quality monitoring network do?

Readings: Each node measures PM2.5, PM10, NO2, ozone, temperature and humidity every minute and sends a 10-minute summary.
Live map: A public map shows a current index per neighbourhood, updated every 10 minutes.

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How well must it do it?

Trustworthy data: Every published value is corrected by calibration and carries a quality flag; bad readings never reach the map.
Power: Nodes run on solar and keep working through 5 cloudy days.

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What scale should you design for?

Use these numbers in your estimates.

The scale numbers unlock with this questionUnlock

Key concepts

LoRaWAN
Sensor calibration
AQI
PM2.5
Solar power budget
Data quality flags

How you’ll practise

6 short steps · save and come back any time

Requirements
Estimate
Device and connectivity
Ingestion and processing
Device management and updates
Wrap-up

Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.

What do interviewers look for?

In any IoT system design round.

Clarifies device count, message rate and payload size
Handles devices that go offline and reconnect
Plans ingestion that absorbs bursts
Separates hot real-time data from long-term storage
Covers device identity, updates and security
Explains what runs on the device and what runs in the cloud

Questions people ask about this interview question

Which design type is this question?: It is an ioT system question. You design an air quality monitoring network and explain your choices the way you would in an interview.
Is this question asked at entry level?: It is marked Easy, so it suits engineers who are new to ioT system interviews. It is also a good warm-up before harder questions.
What should I cover first?: Start with the devices, what they send, how often and what must happen with it. Agree on scope with the interviewer before you design anything.
Can I practise it for free?: It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.

The problem

What must an air quality monitoring network do?

How well must it do it?

What scale should you design for?

Key concepts

How you’ll practise

What do interviewers look for?

Questions people ask about this interview question

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