how to compute spot reading for PM2.5 index

it’s common knowledge to go to NEA’s hazeDOTgovDOTsg to obtain the 24-hr and 3-hr average PSI reading (:

but for whatever reason, if you would like to know the past 1-hr reading (aka spot reading) for the PM2.5 index, NEA also provides the data to us. as it is data, you will need to do some quick manual ‘computation’ to turn it into useful information. here’s the steps:

1. visit the Pollutant Concentration page

2. scroll slightly down to find the default 24-hr Sulphur Dioxide readings.

3. click on the dropdown listbox, select 1-hr PM2.5.

4. visit AQI calculator hosted by, and key in the readings from NEA webpage to obtain information about the air quality for the past 1-hr.

5. if you are lazy to go through steps 1-4, you could either visit the AQICN website, or download the Asia Air Quality app in Google Play Store or iOS App Store, OR

6. perform steps 1-3, and remember that any reading above 55µg/m3 is in the Unhealthy range.

Screenshot 2015-08-25 21.40.44

//update 14/9

recently i’ve been posting screenshots to fb timeline to update on AQI spot readings. these are but widgets from the asia air quality app (instructions for iOS can be found on

2015-09-10 14.57.19

//update 25/9
do note that AQI & NEA’s PSI readings may not be equal. AQI shown above takes a direct computation of PM2.5 figures only. PSI on the other hand is a composite figure; the details on how to compute PSI can be found under NEA’s FAQs, or a direct link from here.

//update end

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