Roland Turner

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Yet Another Haze Index (Yahi)

Yahi Overview
Relationship between Yahi and PSI
Mapping Pilot
Assembly Instructions
Installation Instructions
Approx 0-50 Good Near-real-time (30-90s delay) visualisation of the samples from the deployed sensors.

The colours are intended to be comparable to those used by the NEA for its PSI reporting, but do take note that the sensors in use only give an approximation of the NEA's measurements. Further, when the approximation was constructed, I did not have readings in the yellow/orange/red zones, so these are pure extrapolation at present.

See Relationship between Yahi and PSI for more detail.
Approx 51-100 Moderate
Approx 101-200 (extrapolated)Unhealthy
Approx 201-300 (extrapolated)Very Unhealthy
Approx 301+ (extrapolated) Hazardous


Yahi is an experiment in using very-low-cost dust sensors to collect and map more detailed information about Singapore's haze than can cost-effectively be collected with lab-quality instruments:

I am looking for volunteers to purchase a sensing station and install it on a balcony or a roof to provide data for the project. The sensing station is available from 12Geeks as an assembled and tested kit for $95 (plus a plug pack if you don't have a spare one lying around).


This project has two objectives during Singapore's haze season:


The basic approach is to:

These low cost sensors lack the precision of lab instruments but are expected to provide a sufficiently accurate proxy to meet the project's objectives.


The initial rollout of sensors is underway:

Next steps include:

Getting Involved

If you'd like to host a sensor, particularly if you'd like to do so in a part of the map that currently has no coverage, please see the mapping pilot page.


Recent State of Fires in Region

TODO: Put regional extract from NASA's Global Fire Maps here.

Sensing Station

The current components are:

They are available as an assembled, tested kit from 12Geeks. $95

If you don't have one lying around, you'll also need a USB plug pack. $9

Depending upon how you're installing it, you might prefer a more compact USB plug pack like the one in the photo above. $20

Data Uploading

The current plan is:

Data visualisation

For last-24-hours haze intensity trend graphs:

For propogation visualisation, the initial approach is to use Google Maps javascript API to draw circles directly on the map of Singapore as at the top of this page, and then display a last-24-hours animation.

A map snapshot for the benefit of web-crawlers that can't "see" Google Maps: