JAS explains why independent AQI apps often show higher readings than Malaysia’s official index

JAS acknowledged reports of free websites and mobile applications showing Air Quality Index (AQI) numbers that sometimes surpass Malaysia’s official Air Pollutant Index (IPU). In a statement, the agency clarified that such differences do not automatically indicate a contradiction or an under-statement of pollution levels. Instead, they usually result from the use of distinct scales, calculation formulas, threshold values, averaging windows and update cycles, as well as differing data sources.

The official IPU is derived from hourly averages of six key pollutants—ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, PM10 and PM2.5—measured continuously over a 24-hour period. By contrast, many international platforms adopt the U.S. AQI scale and may rely on low-cost sensors, model estimates or satellite-derived particle densities, which can misread water vapor or clouds as haze. Because satellite data reflect atmospheric layers rather than ground-level conditions, direct number-for-number comparisons are misleading. JAS therefore advises the public to obtain air-quality information from the official APIMS portal or the MyJAS EQMS application to ensure consistency and health-related decision-making.