Asian Journal of Atmospheric Environment Vol. 9-2, pp. 101-113, June 2015 Ozone Concentration in the Morning in InlandISSN(Online) Kanto Region 2287-1160 101 doi: http://dx.doi.org/10.5572/ajae.2015.9.2.101 ISSN(Print) 1976-6912 A Review on Air Quality Indexing System Kanchan, Amit Kumar Gorai1),* and Pramila Goyal2) Department of Civil and Environmental Engineering, Birla Institute of Technology, Mesra, Ranchi­835215, India 1)Department of Mining Engineering, National Institute of Technology, Rourkela, Odisha­769008, India 2)Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi, Delhi­110016, India *Corresponding author. Tel: +91­661­2462938, E­mail: [email protected] Globally, many cities continuously assess air quality ABSTRACT using monitoring networks designed to measure and record air pollutant concentrations at several points Air quality index (AQI) or air pollution index (API) is deemed to represent exposure of the population to commonly used to report the level of severity of air these pollutants. Current research indicates that guide­ pollution to public. A number of methods were dev­ eloped in the past by various researchers/environ­ lines of recommended pollution values cannot be regar­ mental agencies for determination of AQI or API but ded as threshold values below which a zero adverse there is no universally accepted method exists, which response may be expected. Therefore, the simplistic is appropriate for all situations. Different method comparison of observed values against guidelines may uses different aggregation function in calculating mislead unless suitably quantified. In recent years, air AQI or API and also considers different types and quality information are provided by governments to the numbers of pollutants. The intended uses of AQI or public comes in a number of forms like annual reports, API are to identify the poor air quality zones and environment reviews, and site or subject specific anal­ public reporting for severity of exposure of poor air yses/report. These are generally having available or quality. Most of the AQI or API indices can be broad­ access to limited audiences and also require time, inter­ ly classify as single pollutant index or multi­pollut­ est and necessary background to digest its contents. ant index with different aggregation method. Every Presently, governments throughout the world have also indexing method has its own characteristic strengths started to use real­time access to sophisticated database and weaknesses that affect its suitability for particu­ management programs to provide their citizens with lar applications. This paper attempt to present a access to site­specific air quality index/air pollution review of all the major air quality indices developed index and its probable health consequences. Thus, a worldwide. more sophisticated tool has been developed to commu­ nicate the health risk of ambient concentrations using Key words: Air pollution, Air quality index, Health, air pollution index (API) or air quality index (AQI). Environmental factors, Literature review The World Health Organization (WHO) estimates that 25% of all deaths in the developing world can be direct­ ly attributed to environmental factors (WHO, 2006). 1. INTRODUCTION The problem of air pollution and its corresponding ad­ verse health impacts have been aggravated due to in ­ Air pollution is global environmental problem that creasing industrial and other developmental activities. influences mostly health of urban population. Over the The monitoring concentrations of pre­determined air past few decades, epidemiological studies have dem­ pollutants in the residential/commercial/industrial areas onstrated adverse health effects due to higher ambient are used for the calculation of an air quality index (AQI) levels of air pollution. Studies have indicated that rep­ or air pollution index (API). The monitoring data are eated exposures to ambient air pollutants over a pro­ aggregated and converted into a single index with a longed period of time increases the risk of being sus­ variety of methods. This means that indexing systems ceptible to air borne diseases such as cardiovascular and air pollution descriptors often differ from one coun­ disease, respiratory disease, and lung cancer (WHO, try/region to another. The indicators of air quality give 2009). Air pollution has been consistently linked to the public an opportunity to track the state of their substantial burdens of ill­health in developed and devel­ local, regional and national air quality status without oping countries (Gorai et al., 2014; Bruce et al., 2000; the need for an understanding of the details of the mon­ Smith et al., 2000; WHO, 1999; Schwartz, 1994). itoring data upon which they are based. Since the sen­ 102 Asian Journal of Atmospheric Environment, Vol. 9(2), 101-113, 2015 sitivity of the people to expose of air pollution chang­ mental agencies/researchers for different country/re ­ es with changing in geographical location, quality of gions. Though, there is a widespread use of air pollu­ life etc., an universal technique to measure the air qua­ tion (quality) index systems but currently no interna­ lity index is not very much helpful. tionally accepted methodology for constructing such a system (Stieb et al., 2005; Maynard and Coster, 1999) 1. 1 ‌Design Criteria for an Ideal Air Quality are available. In this paper, an attempt has been done Index to demonstrate the critical review on different AQI The basic objective of any air quality index is to systems. transform the measured concentrations of individual In 1976, the U.S. EPA established a Pollutant Stan­ air pollutant into a single numerical index using suit­ dards Index (PSI) which rated air quality. They sug­ able aggregation mechanism. Ideally, every index gested the formula for aggregating pollutants to deter­ should reflect both the measured and publicly per­ mine PSI. The index ranged from 0­500, with 100 ceived quality of the ambient air for the time period it equal to the National Ambient Air Quality Standards covers. As a result, air quality indices attempt to stan­ (NAAQS). The PSI is calculated for every pollutant dardize and synthesize air pollution information and with a NAAQS, but the only level reported for a given permit comparisons to be readily undertaken, and to time and location is for the pollutant most exceeding satisfy public demands for accurate, easy to interpret its standard. The daily PSI is determined by the high­ data. In design of air quality indices, the following cri­ est value of one of the five main air pollutants: partic­ teria should be used: ulate material (PM10), ozone (O3), sulfur dioxide (SO2), 1. be readily understandable by the public; carbon monoxide (CO), and nitrogen dioxide (NO2). 2. ‌include the major criteria pollutants and their syn­ The PSI does not indicate exposure to many other pol­ ergisms; lutants, some of which may be dangerous for people 3. ‌be expandable for other pollutants and averaging with respiratory problems (Qian et al., 2004, Radojevic times; and Hassan, 1999). The PSI was revised, renamed to 4. ‌be related to National Ambient Air Quality stan­ the Air Quality Index (AQI), and subsequently imple­ dards used in individual provinces; mented in 1999 by the U.S. EPA. 5. ‌avoid “eclipsing” (eclipsing occurs when an air pollution index does not indicate poor air quality 2. 1 AQI System of U.S. EPA despite the fact that concentrations of one or more U.S. EPA’s AQI is defined with respect to the five air pollutants may have reached unacceptably main common pollutants: carbon monoxide (CO), high values); nitrogen dioxide (NO2), ozone (O3), particulate mat­ 6. ‌avoid “ambiguity” (ambiguity occurs when an air ter (PM10 and PM2.5) and sulphur dioxide (SO2). The pollution index gives falls alarm despite the fact individual pollutant index as in the eqn. (1) is calculat­ that concentrations of all the pollutants are within ed first by using the following linear interpolation the permissible limit except one); equation, pollutant concentration data and reference 7. ‌be usable as an alert system; concentration. The breakpoint concentrations have 8. ‌be based on valid air quality data obtained from been defined by the EPA on the basis of National monitoring stations that are situated so as to rep­ Ambient Air Quality Standards (NAAQS) as shown in resent the general air quality in the community; Table 1, and on the results of epidemiological studies which refer to the effect of single pollutants on human health. 2. REVIEW OF AIR QUALITY (IHI -ILO) Ip = ------------------- (CP -BPLO)+ILO (1) INDICES (AQI) BPHI -BPLO where The large databases often do not convey the air qual­ I =Index for pollutant P ity status to the scientific community, government P C =Rounded concentration of pollutant P officials, policy makers, and in particular to the gener­ P BP =Break point that is greater than or equal to C al public in a simple and straightforward manner. This HI P BP =Breakpoint that is less than or equal to C problem is addressed by determining the Air Quality LO P I =AQI value corresponding to BP Index (AQI) of a given area. AQI, which is also known HI HI I =AQI value corresponding to BP as Air Pollution Index (API) (Murena, 2004; Ott and LO LO Thom, 1976; Thom and Ott, 1976; Shenfeld, 1970) or The highest individual pollutant index, IP, represents Pollutant Standards Index (PSI) (U.S. EPA, 1994; Ott the Air Quality Index (AQI) of the location. and Hunt, 1976), was developed by various environ­