KUALA LUMPUR, Oct 12 — Air quality worsened across the country this afternoon, with 23 of the nation's 68 monitoring stations recording unhealthy Air Pollutant Index (API) readings, according to the Department of Environment (DOE).

As of 4.50pm, 41 stations recorded moderate air quality and four were in the good range. No station recorded very unhealthy or hazardous levels. An Air Pollutant Index (API) reading of 101 to 200 is classed as unhealthy.

Pasir Gudang in Johor recorded the highest reading at 174, followed by Kota Tinggi, also in Johor, at 170. Seremban in Negeri Sembilan was third at 167, followed by Pengerang in Johor at 166 and Nilai in Negeri Sembilan at 164.

Johor had seven stations in the unhealthy range. Besides Pasir Gudang, Kota Tinggi and Pengerang, the others were Larkin at 160, Batu Pahat at 156, Tangkak at 152 and Kluang at 151. Segamat, which was in the unhealthy range this morning, no longer appeared on the list.

Negeri Sembilan had three unhealthy stations, with Port Dickson at 154 in addition to Seremban and Nilai.

In Melaka, Bukit Rambai logged 161, Bandaraya Melaka 155 and Alor Gajah 153. Putrajaya recorded 156, up from 146 this morning and above the 150 mark that authorities there had cited as the closure threshold.

In Pahang, Balok Baru in Kuantan recorded 162 and Rompin 155. In Terengganu, Kemaman recorded 155 and Paka 153, while Johan Setia in Selangor stood at 152.

Unhealthy readings also appeared in East Malaysia, which was not among the areas listed this morning. In Sarawak, IPD Serian recorded 155, Sri Aman 153 and Samarahan 148, while in Sabah, Tawau logged 149.

Several readings have also risen since the morning. Pasir Gudang climbed from 168 to 174, Seremban from 164 to 167, and Bukit Rambai from 153 to 161. Alor Gajah in Melaka jumped from 101 to 153, Port Dickson from 137 to 154 and Johan Setia from 129 to 152. Kota Tinggi held at 170.

Earlier, Education Minister Datuk Seri Fadhlina Sidek announced that schools in Johor, Melaka, Negeri Sembilan and Putrajaya will be closed tomorrow.

The closures also cover schools under the district education offices of Hulu Langat, Petaling Perdana, Kuala Langat and Sepang in Selangor, and Kuantan and Rompin in Pahang. Schools elsewhere will operate as usual.

Health and education authorities have advised parents, high-risk groups and students with respiratory symptoms to wear face masks and check real-time air quality updates through official channels.