Malaysia's low-cost carrier Firefly has extended the suspension of its flights connecting Kuala Lumpur and Singapore through Wednesday, citing persistent smoke from Indonesian wildfires.

The cancellations come as air quality monitoring firm IQAir identified Singapore and Malaysia's capital, Kuala Lumpur, as the world's two most polluted cities on Tuesday. This marks a significant disruption for regional travel and highlights the severity of the environmental crisis.

Firefly stated that flights between Sultan Abdul Aziz Shah Airport (SZB) near Kuala Lumpur and Singapore's Seletar Airport (XSP) are suspended due to "weather and haze conditions," a move described as a "proactive safety measure." The airline is rebooking affected passengers onto Malaysia Airlines flights, subject to availability.

This decision underscores the far-reaching impact of the fires, primarily raging on the Indonesian islands of Sumatra and Borneo. These fires, exacerbated by the strong El Nino weather pattern, are reportedly the most intense in 11 years, leading to widespread air pollution across Southeast Asia.

Air Quality Index (AQI) readings in Singapore reached 199 and in Kuala Lumpur 183 on Tuesday, according to IQAir. AQI levels above 150 are considered unhealthy, while those exceeding 300 are classified as hazardous. The Singaporean government has reinstated subsidies for haze-related illnesses, a measure last seen in 2015 when similar conditions prevailed.

In Malaysia, while schools in most states reopened on Tuesday as air quality saw slight improvements, educational institutions in three states, one federal territory, and several districts remain closed. The Malaysian government is seeking stronger regional cooperation to address the issue.

Malaysia's Foreign Minister Mohamad Hasan announced plans to advocate for the inclusion of haze in ASEAN's disaster management mechanisms. He noted that the current ASEAN framework does not classify haze as a natural disaster, a point he intends to raise at an upcoming ASEAN foreign ministers' meeting.

The Philippines, as the current ASEAN chair, has confirmed that haze will be on the agenda for the November meeting, which will precede the 49th ASEAN summit in Manila. Indonesia has reportedly deployed approximately 60,000 personnel to combat the fires.