SINGAPORE — The air quality reached "hazardous" levels as the three-hour Pollutant Standards Index (PSI) reading spiked to 321 at 10pm — from 290 an hour earlier. It is now at an all-time high, exceeding the 1997 reading of 226. When the PSI is above 301, air quality is deemed “hazardous”. At 11pm,. the 3-hour PSI reading fell to 282, back to "very unhealthy" levels. A ministerial statement is expected "shortly", according to Member of Parliament Alex Yam. Posting on his Facebook page, Mr Yam said: "Dear all, I have just confirmed with Minister for the Environment and Water Resources that the 290 PSI reading is not a typo. Please stand by for a Ministerial Statement to be issued shortly." Mr Yam urged the public "to take all necessary precautions. Do not undertake strenuous activities". According to the National Environment Agency, when the PSI is in the “hazardous" range, children, elderly and persons with existing diseases should stay indoors and avoid outdoor activity. The general population should avoid unnecessary outdoor activity. In a Facebook post, the Singapore Armed Forces (SAF) said that as at 9pm today, it has "ceased all outfield training until further notice to ensure the well-being and safety of our soldiers". "Since this afternoon, we have issued our Soldiers on duty with the N95 masks. Our ground Commanders have also been reminded to keep a close watch on our Soldiers. We are closely monitoring the situation and will take additional precautionary measures as necessary," the SAF wrote. At 3pm today, the PSI hit 172 before dropping to 158 an hour later and to 146 at 5pm. At 7pm, the PSI had risen back to 161 and has climbed higher since then. PSI readings of 50 and below denote “good” air quality, “moderate” for 51-100, “unhealthy” for 101-200. The three-hour PSI readings are calculated based on PM10 concentrations only. Indonesia has announced that it plans to use cloud-seeding to create rain and extinguish the fires on Sumatra island, but the operation will take place earliest on Friday as preparations need to be made. Meanwhile, Malaysia has banned open burning in Selangor, Malacca and Johor — the states are currently suffering from the haze — until further notice. In an interview with the BBC, Environment and Water Resources Minister Vivian Balakrishnan said the haze has been a recurrent problem for almost two decades and Singaporeans are “very frustrated, angry and distressed about the situation”. He said it is not a matter of traditional slash-and-burn agriculture, but “an industrial-scale deforestation and irresponsible commercial exploitation of the land”. Thus, what is needed is “political will, effective enforcement and better collaboration between countries”. Earlier today, Minister for Foreign Affairs and Law, K Shanmugam responded in a Facebook post to criticism by some members of the public, who questioned why the Government cannot do more about the haze situation. “Look at the map, see where we are. Every country is sovereign and we can’t intervene in the actions in other countries,” said Mr Shanmugam. “The burning is taking place in Indonesia. What do you think Singapore can do about that?” Pointing out that Singapore has raised the matter with Indonesian ministers, and has, over several years, “offered technical assistance, expressed our deep distress at what is happening, and have also raised the issue internationally”, he said: “The problem recurs, nevertheless.” Despite the fact that “we are often price takers, not price makers”, Singapore has “done well” compared to bigger countries with more resources “because we have managed to deal with most situations by anticipating them”, he noted. “But the haze situation is quite outside our control.” Thanking “those who have noted the reality of the situation, and the limitations within which we operate”, Mr Shanmugam said that if anyone “thinks we can do more about the haze that is caused by burning in Indonesia, perhaps they can tell us”. “But I suppose, for some, the temptation to direct expletives and use this occasion to attack the Govt and the PAP is too great,” he added. Separately, Deputy Prime Minister Teo Chee Hean also noted in a Facebook post: “The city is slowly disappearing as the haze thickens this morning.” “I hope that cooperation with our neighbour will help to resolve this problem not just for now but the future,” he wrote.