新加坡PSI和PM2.5 AQI:为什么两个读数有差异?
Singapore PSI and PM2.5 AQI: Why is there a difference between the two readings?

Posted on June 25th 2013
分享: aqicn.org/faq/2013-06-25/singapore-psi-and-pm25-aqi-why-is-there-a-difference-between-the-two-readings/cn/
Please note that this article was orginally written in June 2013.
In April 2014, the Singapore NEA has updated the PSI calculation to also include PM2.5. http://www.nea.gov.sg/anti-pollution-radiation-protection/air-pollution-control/psi

With the recent Southeast Asia Smog from Indonesia affecting Singapore and now Malaysia, we got many questions about why there is a difference between the data which can be read from Singapore NEA website (nea.gov.sg) and the World Air Quality Index project Singapore webpage.

例如,今天可以在 NEA 网站上看到以下内容:


由于某些历史原因,新加坡使用PSI污染物标准指数)来评估空气质量。在上图中,数字 1 对应于用于 PSI 评估的 PM10 值。值67(/59)可读取为 67 µg/m3,对应于 PSI 59。PSI 被评估为每种污染物的单个 PSI 的最大值:PM 10 、SO 2 、NO 2 、O 3 (臭氧)和CO 2

PSI(Singapore-North) = max( PSIPM10-based, ... PSIO3-based )= max (59, ..., 77) = 77

尽管如此,有趣的是,在同一个表中,最后一列还提供了 PM2.5 数据(参见图 3)。该数据仅以 μg/m3 为单位提供(参见 2),并且没有转换为 PSI 之类的数据(即从 PM2.5 质量转换为污染或质量指数)。然而,这种转换是存在的,并且是由美国环境保护局定义的。进行转换的最简单方法是使用在线计算器,可在airnow.gov上找到:


If you select the PM2.5 (1), then enter the mass concentration of 48 (2), can click on Calculate, you will obtain the AQI of 132 (3). So, based on the PM2.5 AQI conversion, the PSI that is used for Singapore could be extended (let's call it PSI++) to also take into account the PM2.5 information. In which case, the PSI++ would be the maximum of the regular PSI (based on PM10 only) and the PM2.5 AQI:

PSI++ = max( PSI, AQIPM.25 ) = max( 77, 132 ) = 132

This PSI++, that is commonly referred as AQI (or Air Quality Index), is what is being used on the the World Air Quality Index project, for all the cities (provided PM2.5 is available for the city). And this explains why the values are different between the NEA website and the World Air Quality Index project.

Note: With the PSI update from April 2014, the only remaining difference is that the World Air Quality Index project is using a 1-hour PM2.5 reading (following the instantcast) while Singpore PSI is based on the 3 hours average.

Moreover, when doing the convertion, make sure you use the 1-hour reading for the PM2.5 concentration rather than the 24-hours averaged value, as shown on the below image:


http://www.haze.gov.sg/haze-updates/pollutant-concentrations/type/PM25-1Hr


If you want to know more about PM10 vs PM2.5, and especially why PM10 is still used, please check the faq entry about why is PM2.5 often higher than PM10? Is PM10 still a relevant measure?


--

Note: This article is part of a series on Worldwide Air Quality scales.

For more information about specific countries or continent, please refer to those articles:
Thailand and Malysia
-
India
-
China
-
Hong Kong / Canada (Air Quality Health Index)
-
South America
-
Australia
-
Quebec and Montreal
-
Singapore
-
Poland
-
Indonesia
.

For information about the 24 hours averaging used or Ozone and Particulate Matter (PM2.5), please refer to those two articles: Ground Ozone Index - PM2.5 Instant Cast

单击此处查看所有常见问题解答条目
  • AQI Scale: What do the colors and numbers mean?
  • Using Statistical Distances for Real-time Sensor Networks Validation
  • Nitrogen Dioxyde (NO2) in our atmosphere
  • 关于空气质量与空气污染指数

    本网站采用的污染指数和颜色与EPA是完全相同的。 EPA的指数可以从 AirNow上查到

    空气质量指数空气质量指数级别(状况)及表示颜色对健康影响情况建议采取的措施
    0 - 50一级(优)空气质量令人满意,基本无空气污染各类人群可正常活动
    51 -100二级(良)空气质量可接受,但某些污染物可能对极少数异常敏感人群健康有较弱影响极少数异常敏感人群应减少户外活动
    101-150三级(轻度污染)易感人群症状有轻度加剧,健康人群出现刺激症状儿童、老年人及心脏病、呼吸系统疾病患者应减少长时间、高强度的户外锻炼
    151-200四级(中度污染)进一步加剧易感人群症状,可能对健康人群心脏、呼吸系统有影响儿童、老年人及心脏病、呼吸系统疾病患者避免长时间、高强度的户外锻炼,一般人群适量减少户外运动
    201-300五级(重度污染)心脏病和肺病患者症状显著加剧,运动耐受力降低,健康人群普遍出现症状儿童、老年人及心脏病、肺病患者应停留在室内,停止户外运动,一般人群减少户外运动
    300+六级(严重污染)健康人群运动耐受力降低,有明显强烈症状,提前出现某些疾病儿童、老年人和病人应停留在室内,避免体力消耗,一般人群避免户外活动
    (参考详见http://zh.wikipedia.org/wiki/空气质量指数)

    如果你想了解更多有关空气质量与污染,详见维基百科或者 AirNow

    有关健康建议详见北京的Richard Saint Cyr MD医生的博客:www.myhealthbeijing.com


    注意事项: 所有空气质量数据在发布时均未经验证,并且为了保证数据质量,这些数据可能随时被修改,恕不另行通知。 世界空气质量指数项目在编制此信息的内容时已经运用了所有合理的技能和谨慎,在任何情况下世界空气质量指数项目团队或其代理人将不会为由于提供此数据而直接或间接引起的伤害、合同损失、侵权及其他任何损失负责。



    设置


    选择语言:


    Temperature unit:
    Celcius