the use and treatment of particulate measurements in the ... watts, the use and... · the use and...

The use and treatment of particulate measurements in the assessment and reporting

of air quality

Simon Watts1,2 , Annette Bolton3, Hannah Nguyen1,4

1. Department of Chemistry, National University of Singapore

2. National University of Singapore Environmental Research Institute

3. Earth Observatory of Singapore, Nanyang Technological University

4. Department of Chemistry, University College London (MChem IIII)

Australia and New Zealand Aerosol Workshop 2014 , 10-11 July, Wellington

Copyright National University of Singapore 2011 2

Aperitif particles in the atmosphere

Hor de Ouvres why we might be interested

Main AQIs – what the public hear

Sweet AQIs and smoke plumes

Cheese and Port AQIs and urban pollution

The Smoking Room beyond AQIs

Al la Carte


Particles in the Atmosphere

Kaiser, J. [2005] Science 307 pp1858-9.


Ultra-fine particles greatest number, negligible mass. Mass of a 1 µm particle that of a billion at 0.01 µm

Particles in the Atmosphere

Hester, R.E. Harrison, R.M. [2009] Air Quality in Urban Environments. RSC ISBN 978 1 84755 907 4


Kaiser, J. [2000] Science 289 pp22-23. Six Cities Study.

Why we might be interested



Schwartz, J. et al. [2002] The concentration-response relation between PM2.5 and daily deaths. Env. Health Perspectives 110 (10) pp1025-1029.


Dlfhesr**

Particules Atmospheriqué

Kaiser et al., 2005, Science


Densely agglomerated 35 nm particle conglomerates (>5 μm) found in particle samples collected by sampling PM2.5 directly from lung lining fluid.


Kendall et al., 2002, Lung Cellular and Molecular Physiology


Rückerl, et al. [2011] Health effects of particulate air pollution: a review of epidemiological evidence. Inhalation Toxicology 23 (10) pp555-592.


This Review of mortality (acute and chronic) is of ~400 separate studies



Hester, R.E. Harrison, R.M. [2009] Air Quality in Urban Environments. RSC ISBN 978 1 84755 907 4

PM10 redrawn from WHO data. “averaged” cities, 42/252 meet the AQG.


United Nations Department of Economic & Social Affiairs (Population) [2005] World urbanisation prospects: the 2005 revision. Working Paper ESA/P/WP/200



Globally 3.5 million premature deaths each year1 due to poor AQ, WTP indicates cost2 of US$3.5 T.

In OECD alone (US$1.7T in OECD)3.

Governments motivated to avoid this cost, hence (simple) public information to avoid some of the economic damage of poor AQ, hence Air Quality Indices (AQIs).

1. OECD (2014), The Cost of Air Pollution: Health Impacts of Road Transport, OECD Publishing, doi: 10.1787/9789264210448-en

2. Includes deaths and illness. Across OECD, India and China.

3. About 50% of this directly attributable to road transport.



AQIs – how the public hear about AQ

PM10 PM2.5

CO SO2

O3 NO2

Each of the measured variables has a scale

PSI e.g. PM10

Good 0-50 50

Moderate 51-100 150

Unhealthy 101-200 350

Very Unhealthy 201-300 420

Hazardous 301-400 500


Highest sub PSI gives the AQI value


Two events, one in Singapore, from 19 June 2013 and one from 21 October 2013 in New South Wales, Australia (SeaFire).

(Both images courtesy of NASA Earth Observatory)

AQIs of smoke plumes – AQI flambé

Aqua MODIS, NASA Earth Observatory image by Jeff Schmaltz, LANCE/EOSDIS Rapid Response,



PM2.5 concentration /µg m-3


Introducing Mrs Jones – a little old lady about 75 with gray hair who has a little dog and walks very fast….and travels a lot.



The WHO I hour mean AQG for NO2 is 200 µg m-3. The lowest category here is ~ 5x this.

Mrs Jones and FALSE NEGATIVES.


PSI NO2 /µg m-3

Good 0-50

Moderate 51-100

Unhealthy 101-200 1130

Very unhealthy 201-300 2260




Singapore AQIs of smoke plumes – AQI flambé


Australia AQIs of smoke plumes – AQI flambé


USA AQIs of smoke plumes – AQI flambé


AQIs and urban pollution



Mrs Jones’ Travelogue

Singapore and US, PM2.5 driven indices, “good” AQ at 1000 µg m-3 NO2

Australia and UK, higher pollution events no discrimination

NZ system different – no PM2.5, but PM10 scales so low probably OK. No discrimination higher pollution events.



NZ system different – no PM2.5, highest NZ ~ lowest overseas, management rather than information


• Indexes Driven by PM2.5 > PM10

• Response of a population of human bodies to a cocktail of pollutants (Indexes effectively just use PM)

• PS “Thresholds” need revisiting

• PPS acute vs chronic?

Beyond AQIs ?

nus.edu.sg

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