Air quality in Peninsular Malaysia is worsening, with five areas registering unhealthy Air Pollutant Index (API).

According to the Department of Environment website, as at 7pm, Banting in Selangor registered the highest reading at 128, followed by Putrajaya where conditioned worsened to 119 compared 116 an hour before.

These are followed by Port Klang (113), Nilai (105) and Shah Alam (103).

The air quality in Cheras and Batu Muda improved by 7pm, with API readings there below 100 when they were higher previously.

An API reading of above 100 is deemed unhealthy, while API of 200 to 300 is very unhealthy and a reading above 300 is hazardous.

This marks an increase from 10am, when only Port Dickson and Banting registered API readings above 100.

However, the API reading recorded at Port Dickson at 3pm was on a downward trend, at 87. By 7pm, the API reading there was 85.

Yesterday, Natural Resources and Environment Minister G Palanivel said the haze originated from fires in Central Sumatra, Indonesia, and is expected to last until September.