\n<\/p>\n
The main difference between the indexes lies in the thresholds used for their various air quality categories, said Prof Yim.<\/p>\n
For example, he noted that under AQI, air quality is considered unhealthy when PM2.5, as the dominant pollutant, falls between 55.5 \u00b5g\/m3 and 125.4 \u00b5g\/m3. Under the PSI, the unhealthy range is 56\u00b5g\/m3 to 150 \u00b5g\/m3.<\/p>\n
\u201cThese ranges for determining AQI categories are set by governments according to their situation,\u201d said Prof Yim.<\/p>\n
\u201cSo, it should be noted that the index from other countries may not be applicable directly to a country.\u201d<\/p>\n
Countries also split their index bands differently, said Associate Professor Liya E Yu from the National University of Singapore\u2019s (NUS) Department of Civil and Environmental Engineering.<\/p>\n
For example, she noted that the US AQI is a six-band system as it devotes a specific band to “Unhealthy for Sensitive Groups”.\u00a0<\/p>\n
There is no equivalent band in Singapore\u2019s PSI system or Malaysia\u2019s Air Pollutant Index.<\/p>\n
Singapore’s PSI, however, provides separate health advisories for different population groups, including children, older people and those with chronic heart or lung conditions.<\/p>\n
Singapore’s PSI, the AQI and Malaysia’s API serve the same general purpose – to communicate air pollution levels and their potential health implications to the public, said Provost\u2019s Chair Professor Rajasekhar Balasubramanian from NUS\u2019 Department of Civil and Environmental Engineering.<\/p>\n
But since they differ in calculation methods, concentration breakpoints for each air pollutant, and health categories, their values should not be compared directly without accounting for these methodological differences, he added.<\/p>\n
Dr Yu similarly advised against comparing figures from different systems as it would lead to confusion.<\/p>\n
Instead, people should focus on the health advisories or air quality descriptions that accompany each system\u2019s grading framework to get guidance on activities and plans amid air quality conditions, he said.<\/p>\n<\/div>\n
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The main difference between the indexes lies in the thresholds used for their various air quality categories, said Prof Yim. For example, he noted that…<\/p>\n","protected":false},"author":1,"featured_media":92384,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/dam.mediacorp.sg\/image\/upload\/s--30Z3sf4X--\/c_crop,h_830,w_1476,x_0,y_87\/c_fill,g_auto,h_676,w_1200\/fl_relative,g_south_east,l_mediacorp:cna:watermark:2021-08:cna,w_0.1\/f_auto,q_auto\/v1\/mediacorp\/cna\/image\/2026\/10\/09\/haze_oct_9_10.jpg?itok=qP_6qKDR","fifu_image_alt":"","footnotes":""},"categories":[2],"tags":[31532,15,16710,1339,1488,19324,29441,29530,668],"class_list":["post-92383","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-buzz-news-sg-global","tag-aqi","tag-cna","tag-differ","tag-explains","tag-follow","tag-haze","tag-psi","tag-readings","tag-season","wpcat-2-id"],"brizy_media":[],"_links":{"self":[{"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/posts\/92383","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=92383"}],"version-history":[{"count":0,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/posts\/92383\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=\/wp\/v2\/media\/92384"}],"wp:attachment":[{"href":"https:\/\/sgbuzz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=92383"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=92383"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sgbuzz.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=92383"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}