«Sef van den Elshout October 2014 AQI & AQ Communication D2.3/v07 PartII Work Package 2, Task 2.2 Deliverable D2.3 Version number V07 Ver Date Author ...»
Air quality indices
D2.3 - Part II
Task 2.2 - Air Quality Communication
Sef van den Elshout
AQI & AQ Communication
Work Package 2, Task 2.2
Version number V07
Ver Date Author Comments
01 May 2013 SvdE Lisa Blyth
02 May 2013 SvdE Lisa Blyth, Yu Lei
04 June 2013 SvdE
05 July 2013 SvdE 07 October 2014 SvdE Minor updates to AQI tables, added a chapter on recent developments Corresponding author Sef van den Elshout Sef.email@example.com, +31-10-2468368 DCMR, PO Box 843, 3100AV Schiedam, the Netherlands AirINFORM - EuropeAid Contract DCI-ASIE/2012/299-560 Project Co-ordinator Deputy Co-ordinator Lisa Blyth Lei Yu Project Co-ordinator Assistant Director Atmospheric Modelling Group, VITO Chinese Academy for Environmental Planning www.ecegp.com Mol, Belgium Chaoyang District, Beijing, P.R.China Email: firstname.lastname@example.org Email: email@example.com Tel: (+32-14) 33 67 57 Tel (+86-10)84949507-801 AQ Communication D2.3/V7 part II Table of Contents Introduction _______________________________________________________________ 5
1. Why AQI-s _____________________________________________________________ 6
1.1. Type1: health and behavioural advice AQI-s _____________________________ 7 1.1.1. General properties _________________________________________________ 7 1.1.2. Sub-types of health and behavioural advice AQI-s _______________________ 10
1.2. Type 2: policy/standards based AQI-s _________________________________ 11
1.3. Issues related to all AQI types _______________________________________ 12 1.3.1. The balance between continuity and being up to date ____________________ 12 1.3.2. Time averaging ___________________________________________________ 12 1.3.3. Spatial representativeness __________________________________________ 14 1.3.4. The choice of pollutants in the AQI ___________________________________ 15
2. Recent developments – health based indices ________________________________ 17
2.1. Introduction _____________________________________________________ 17
2.2. The Hong Kong AQHI ______________________________________________ 17
2.3. The Dutch AQI revision project ______________________________________ 18
2.4. Common characteristics of recently revised AQI-s that are in use ___________ 19
3. AQI properties & communication objectives _________________________________ 21
3.1. How to condense information _______________________________________ 21
3.1. Linking AQI properties & communication objectives______________________ 22
3.2. Adapting behaviour? ______________________________________________ 24
4. Other AQI-products (year average, maps, etc)________________________________ 26
4.1. Year average AQI-s. _______________________________________________ 26
4.2. Policy indicators __________________________________________________ 28 4.2.1. The EEA Environmental indicators ____________________________________ 28
4.3. AQI maps _______________________________________________________ 29
5. Literature ____________________________________________________________ 31 Annexes _________________________________________________________________ 32 A1. Selected air quality indices________________________________________________ 32 A1.1 Indices aimed at providing behavioural/health advice _____________________ 32 A1.2 Policy/standards based indices _______________________________________ 37 A2. Apps and websites some examples _________________________________________ 40 A2.1 Apps ____________________________________________________________ 40 A2.2 Websites_________________________________________________________ 42
Boxes Box 1: Simplifying information to make it understandable or to create confusion?.................. 6 Box 2: Short-term / long term exposure communication paradox
Box 3: averaging times for PM
Box 4: Sensitivity of an AQI to the pollutants included
Box 5: Year average AQI-s
Tables Table 1: Typical example of the SO2 concentration ranges in the two types of AQI-s................ 7 Table 2: NO2 calculation grid in the UK AQI
Table 3: Health effects seemingly occur at different concentrations in different countries...... 9 Table 4: Sensitivity of the CAQI index for the pollutants included
Table 5: Netherlands tentative AQI approach
Table 6: AQI types and communication objectives
Table 7: Communication objectives and AQI characteristics
Figures Figure 1: Presentation issues with daily PM values
Figure 2: Canadian messaging: an AQI aimed at risk communication combining awareness messages (what can you do yourself); Source: Stieb et al (2008)
Figure 3: www.obsairve.eu website/app, showing air quality in Europe.
Page 4 of 43 AQ Communication D2.3/V7 part II Introduction This is a document on air quality indices (AQI-s) produced in the framework of the EGP project AirINFORM. It is a fairly general description of various types of AQI-s, strong and weak points and for which purposes they can be used. The information doesn’t apply only to the situation in China, it is meant as background information. The examples provided (mainly in the annexes) do rely heavily on indices, websites and apps that are in use in and around China.
This document can be read independently from the main text (AQ Communication, Part I) and in that case it is simply a description of AQI-s and their role in air quality communication. This Part II occasionally refers to Part I if a specific Chinese issue is addressed. The communication objectives mentioned in this Part II were discussed more extensively in Part I (chapters 2 and 3).
Document Part III appears a year after Parts I and II. It applies Chinese monitoring data to the Chinese and other AQI-s. In Part III some of the issues discussed in this document are actually illustrated with real (unvalidated) Chinese monitoring data.
1. Why AQI-s An air quality index, AQI, condenses complex information on the concentration levels of various pollutants into one or more numbers on a relative scale. This information reduction is considered necessary for communication purposes but it is not without problems. See box 1.
AQI-s can be made for various reasons and in many different ways. Shooter and Brimblecombe (2009) mention two reasons for making an index: linking air quality to health effects to inform the public of poor air quality and provide information on possible remedial action; condense complex information to provide an information overview for policy development or monitoring and/or to check compliance with standards. Access to environmental information obligations (e.g. the Aarhus convention) can also be met by providing easy to understand summary information in the form of an AQI. Garcia et al. (2002) mention that AQI-s are part of an air quality management strategy, they play a role in the communication of such a strategy. This point is made more explicitly by Elshout et al (2008, 2012) giving an additional reason to provide air quality information: drawing the public's attention to air quality issues and raising awareness.
Box 1: Simplifying information to make it understandable or to create confusion?
Though indices are widely used for communication purposes, the assumption that it is necessary to reduce complex information for the consumption by the lay public has rarely been tested. Shooter and Brimblecombe (2009), in a review article on air quality indices, mention (citing Burden and Ellis, 1996) that in Australia, public confidence in reporting on air pollution fell following the introduction of an index. Johnson (2003) observed that different versions of the US AQI did not particularly well at increasing public knowledge or changing people’s behaviour in case of episodes. A nice recent example of the confusion an AQI might create can be found in the FAQ section of the http://aqicn.org/?faq website. In this case the user mistakes the iAQI for the concentrations. (Website publishing monitoring data from China and other Asian countries; accessed on 30-5-2013.) February 2nd 2013 We got a very good and relevant question this week from Severine P., who asked about pm2.5 concentrations versus pm10 concentrations.
What Severine asked in her mail was:
I don't understand why pm2.5 concentrations are often higher than pm10 concentrations. Aren't PM smaller than 2.5 micro included in PM smaller than 10 micro? Thank you for your answer Severine's question is totally correct: PM2.5 are, by definition, particulates smaller than 2.5 micrometers, so indeed, they should also be included as smaller than 10 micrometers. But the assumption about concentration is not correct: PM2.5 concentration can be smaller than PM10, but yet, the converted AQI value can be higher.
This shows that it is important, like in Johnson’s study, to properly test all communication messages.
There are several ways of making an AQI. The reason for making an AQI determines to some extent how it is best made. I divide AQI-s in two main types: 1. those aimed at providing behavioural and health recommendations in case of pollution episodes (risk communication);
and 2. those aimed at providing general information based on policy considerations. AQI-s aimed at raising awareness are a special case of the latter.
Usually the two can easily be told apart: Type 1 AQI-s use health descriptions in the labelling of their bands and provide advice, whereas Type 2 AQI-s speak about high and low pollution or good/bad air quality. The second major difference is that the concentration bands in Type 1 are usually much higher than those in Type 2. Short-term exposure is mainly a risk at very high concentrations hence the very wide concentration rage needed in Type 1 AQI-s.
Type 2 AQI-s, linked to standards, often also relate somehow to long-term exposure and therefore tend to have a narrower range. See table 1 for an example of the UK AQI (COMEAP,
2011) and the CAQI (Elshout, 2012, 2014). The US EPA AQI is a typical example of a type 1 index aimed at providing short-term health and behavioural advice. It spans a very wide concentration range.
1.1. Type1: health and behavioural advice AQI-s 1.1.1. General properties These AQI-s have an important communicational characteristic: they provide a link between air quality and health. Also from the point of view of raising awareness on air quality this is an advantage. However, they also have several conceptual problems and that is one of the reasons why the policy/standards based indices (see section 1.2) are popular as well. The main issues are
- The underlying science is still developing and as a consequence different AQI-s provide different health advice at the same pollutant levels. This is awkward form a communication point of view, and it doesn't aid in making the provided information credible (apart from climate sceptics, there are also air pollution sceptics). This is further complicated by the fact that air pollution is a complicated mixture and that it is often not clear which pollutant is exactly causing the health effect(s). Think about NO2, which was first considered a health relevant pollutant, later more of an indicator for (traffic related) combustion aerosol (of which the exact toxic components were not known and not commonly monitored) and recently there is new epidemiologic evidence that NO2 might be a health relevant pollutant after all.
- A second more important problem is the fact that air pollution has health effects at two time scales: short term effects at high concentration levels and long term effects at low or even any level of pollution. WHO provides recommendations for both exposure times for most pollutants, reflecting the different exposure times where one (the short-term exposure) guideline is much
higher than the one for long-term exposure. This can lead to an absurd communication paradox:
in a certain city the health based AQI, aimed at providing advice in case of short term exposure risks, could always signal that air quality is good. Interested or concerned citizens looking at the website at regular intervals would always see an air quality that is labelled good. However, at the end of the year the same city could be required to make an air quality action plan because the year average air quality does not meet the year average standards. Policy based AQI-s seek to avoid this paradox, for health based indices this is unavoidable. See box 2.
Box 2: Short-term / long term exposure communication paradox
Look at the UK iAQI for NO2. If the NO2 hourly concentration has been 50 µg/m3 all year the lay public visiting the website, has seen that the air pollution was low throughout the year, labelled with the lightest colour green available. However from the year average point of view a year average of 50 µg/m3 is unacceptable (standard to be met in the EU by
2015) and this can have severe implications. In the Netherlands this could lead to a ban of adding new economic activities (in the past widening of roads has been blocked by ambient NO2 concentrations slightly over 40 µg/m3). EU countries risk being fined by the commission if they don’t meet the standard.
Table 2: NO2 calculation grid in the UK AQI
The problem that a concentration of 50 can be good and bad at the same time can’t be fully solved. The policy based indices address this somewhat by introducing bands like medium and high at much lower concentrations than the health based indices. This way people visiting the website will occasionally see that the concentrations are not always in the lowest bands, in the good/green.