The Air Pollutant Index (API) makes for dismal reading for those living in the north of Peninsular Malaysia.

The number of areas with 'moderate' air quality had increased to 41 as at 11am today, from 38 at 5pm yesterday.

Seberang Jaya 2 in Perai, Penang, currently has the highest API reading of 98, a few points short of the 'Unhealthy' mark of 101.

Seri Manjung in Perak is close behind with a reading of 93, while the levels in Selangor range from the mid-60s to 86 in Klang.

According to the API, a reading of 101-200 is considered 'unhealthy'.

Visibility has also decreased to between 2km and 5km in Butterworth, Bayan Lepas, Perai and Alor Setar compared to 6-8km yesterday.

Visibility in the rest of the peninsula and Sabah and Sarawak is around 10km.

The Meteorological Services Department has attributed the haze to the burning of forests in Indonesia.

Some 200 hotspots have already been detected in Sumatra, a situation that is expected to be aggravated by dry conditions in Malaysia for the rest of the week.