#sghaze: before and after

The seasonal occurrence of the haze in Singapore hit historic levels on June 21 as the three-hour PSI reached a record high of 401, blanketing the island and placing the air quality in the hazardous range. In many parts of Singapore, TODAY readers reported low visibility - the Republic's skyline, once clearly visible, was shrouded in the smog.
Monday, 01 July 2013
Graphics by Rodolfo Carlos Pazos
Photos by Don Wong, Ernest Chua, Ooi Boon Keong, Xabryna Kek
Research by Xabryna Kek, Hiranand Sunny

Drag the slider below to view pictures of the Singapore skyline before and after the haze

A note on PSI readings: The PSI index was developed by the United States’ Environmental Protection Agency (EPA) to provide accurate and timely information about daily levels of air pollution. Air pollutants such as sulphur dioxide, nitrogen dioxide, ozone, carbon monoxide and particulate matter called PM10 (particulate matter of 10 microns or smaller in size) are used in the determination of the index. The PM2.5 reading measures fine particles measuring 2.5 micrometres or less in diameter, as well as ultrafine particles, and soot. The three-hour PSI readings are calculated based on PM10 concentrations only.

PSI Air quality descriptor
0-50: Good
51-100: Moderate
101-200: Unhealthy
201-300: Very unhealthy
+300: Hazardous

More about the PSI: