周一（9月28日），新加坡中部和南部的空气质量进入不健康水平。
Air quality in the central and southern parts of Singapore entered the unhealthy range on Monday (Sep 28), The 24-hour Pollutant Standards Index (PSI) readings for the central and southern regions hit 104 and 103 respectively as of 8pm.
截至晚上8点，中部和南部地区的24小时空气污染指数（PSI）分别达到104和103。过去几周，PSI读数一直在不健康水平上下波动。
PSI readings have dipped in and out of the unhealthy range over the past weeks.
新加坡国家环境局（NEA）在周一晚间的最新媒体公告中表示，预计未来24小时内，24小时PSI将处于中等偏高至中等不健康范围。
In its latest media advisory on Monday evening, the National Environment Agency (NEA) said that the 24-hour PSI was forecast to be in the high moderate to mid-unhealthy range for the next 24 hours.
NEA指出，苏门答腊南部和加里曼丹火灾产生的浓烟已飘至新加坡。
Moderate to dense smoke haze from fires in southern Sumatra and Kalimantan have drifted to Singapore, said NEA.
尽管预计周二新加坡会有阵雨，但仍存在烟霾影响的风险，且盛行风预计将从东部或东南部吹来。
While some showers are forecast in Singapore on Tuesday, there remains a risk of smoke haze affecting Singapore, with the prevailing winds expected to blow from the east or southeast.
24小时PSI是新加坡衡量每日空气质量的指标，也是国家环境局发布每日健康建议的基础。
The 24-hour PSI is Singapore's indicator of daily air quality and forms the basis of NEA's daily health advisories.
它通过六种空气污染物计算得出，包括PM2.5、PM10、臭氧、二氧化硫、二氧化氮和一氧化碳。
It is calculated using six air pollutants - PM2.5, PM10, ozone, sulphur dioxide, nitrogen dioxide and carbon monoxide.
另一方面，1小时PM2.5读数是PM2.5污染物水平的小时平均值。
The 1-hour PM2.5 reading, on the other hand, is the hourly average of the PM2.5 pollutant levels.
PM2.5是直径为2.5微米或更小的细颗粒物，是烟霾期间对健康造成危害的主要污染物。
PM2.5 is fine particulate matter with a diameter of 2.5 micrometres or shorter, and is the dominant pollutant during haze that causes harm to health.
24小时PSI是过去24小时的平均值，而1小时PM2.5读数则反映了特定时间点的空气质量。
While the 24-hour PSI is an average of the past 24 hours, the one-hour PM2.5 reading reflects the air quality at a single point in time.
24小时PSI读数在101至200之间被视为“不健康”，201至300之间为“非常不健康”，超过300则为“危险”。
A 24-hour PSI reading is considered "unhealthy" when it is in the 101 to 200 range, "very unhealthy" when it is within the 201-300 range, and "hazardous" when it goes over 300.