Statistical evaluation of PM10 and distribution of PM1, PM2.5, and PM10 in ambient air due to extreme fireworks episodes (Deepawali festivals) in megacity Delhi
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- Tiwari, S., Chate, D.M., Srivastava, M.K. et al. Nat Hazards (2012) 61: 521. doi:10.1007/s11069-011-9931-4
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Temporal variation of PM10 using 2-year data (January, 2007–December, 2008) of Delhi is presented. PM10 varied from 42 to 200 μg m−3 over January to December, with an average 114.1 ± 81.1 μg m−3. They are comparable with the data collected by Central Pollution Control Board (National Agency which monitors data over the entire country in India) and are lower than National Ambient Air Quality (NAAQ) standard during monsoon, close to NAAQ during summer but higher in winter. Among CO, NO2, SO2, rainfall, temperature, and wind speed, PM10 shows good correlation with CO. Also, PM10, PM2.5, and PM1 levels on Deepawali days when fireworks were displayed are presented. In these festive days, PM10, PM2.5, and PM1 levels were 723, 588, and 536 μg m−3 in 2007 and 501, 389, and 346 μg m−3 in 2008. PM10, PM2.5, and PM1 levels in 2008 were 1.5 times lower than those in 2007 probably due to higher mixing height (446 m), temperature (23.8°C), and winds (0.36 ms−1).
KeywordsHazardous particlesFireworksMixing heightAir qualityVehicular pollution
Ambient aerosols with mass median aerodynamic diameter less than 10 μm (PM10), 2.5 μm (PM2.5), and 1 μm (PM1) are of interest owing to their effects on human health, visibility, and climate (Watson 2002; Pope and Dockery 2006; IPCC 2007; Pope et al. 1995, 2004; Chate 2011). Increasing particulate matter has already adversely affected human health in megacities (>10 million people; Madronich 2006). In megacities, main sources of PM10, PM2.5, and PM1 are the combustion of fossil fuels from automobiles, construction equipments (mobile sources), furnaces, and power plants (stationary sources). Fine particles (PM2.5 and PM1) are emitted by combustion, while coarse particles (PM10) are blown into the ambient air by mechanical processes (Faiz et al. 1992; Madronich 2006). PM10, CO, NO2, O3, SO2, and volatile organic compounds are periodically monitored and regulated as they have complex, additive, synergistic, or sequential biological effects (Morawska et al. 2002; Maynard and Kuempel 2005). For Instance, PM10 and CO, NO, and NO2 have been assessed over 6 weeks in the Tuhobic road tunnel (2,140 m), Croatia (Ivan et al. 2005). However, regression analysis of PM10 with trace gases and meteorological parameters using relatively large data is lacking for megacities and sparse in the literature. The present study thus assumes significance and forms the subject matter in this first part.
Firecrackers are made up of variety of chemicals (potassium nitrates, potassium chlorate, potassium per-chlorate, charcoal, sulfur, manganese, sodium oxalate, aluminum and iron dust powder, strontium nitrate, barium nitrate, etc.; Mclain 1980). On combustion, they release numerous hazardous pollutants (sulfur dioxide, carbon dioxide, carbon monoxide, suspended particles, aluminum, manganese cadmium, etc.) that affect human health (Hirai et al. 2000; Ravindra et al. 2001). Bach et al. (1975) reported an increase in total suspended particulate matter (TSPM) on an average of 300% at 14 locations and by 700% in the lung penetrating size ranges at one location due to fireworks on New Year’s Eve. Increase in particle number is witnessed in the accumulation mode range (>100 nm) during the Millennium fireworks in Leipzig, (Germany; Wehner et al. 2000). Liu et al. (1997) reported the chemical composition and particle size of typical firework mixtures. Rise in PM2.5 up to 6 and PM10 up to 4 times on a lantern day (fireworks) in Beijing (China) found relative to those over normal days (Wang et al. 2007).
In India, during Deepawali, fireworks on huge scale especially in urban areas add large amount of anthropogenic pollutants into local environment. For example, Ba, K, Al, and Sr levels rose up to 1,091, 25, 18, and 15 times higher (Kulshrestha et al. 2004), black carbon increased by a factor of 3 (Babu and Moorthy 2001), and SO2, NO2, PM10, TSP by 2–10 times (Ravindra et al. 2003) during Deepawali. Several interesting results are reported in literature related to Deepawali fireworks over different parts of India (Agarwal et al. 2006; Barman et al. 2008; Kakoli and Gupta 2007; Kulshrestha et al. 2004; Singh et al. 2003; Singh et al. 2008). Babu and Moorthy (2001) observed a large increase in carbon particles after Deepawali festival in Thiruvananthapuram. Three fold increases in PM10 and TSPM were attributed to fireworks at Hisar, India (Ravindra et al. 2003). Kulshrestha et al. (2004) documented high levels of different trace elements in air at Hyderabad, (India). For the first time, Attri et al. (2001) found O3 formation by sparklers during Deepawali nights at Delhi. To the authors’ knowledge, very few measurements of PM10, PM2.5, and PM1 have been made during firework episodes of Deepawali, over the Indian region.
In this paper, the results are presented in the following order (i) Temporal variation of PM10, (ii) regression analysis of PM10 with CO, NO2, O3, and SO2 and meteorological parameters, and (iii) Variations in PM10, PM2.5, and PM1 levels two extreme firework episodes (Deepawali-2007 and 2008). At the end, PM1 variations in the ambient air during these firework display episodes at Delhi are discussed in terms of health hazard.
2 Observational Site
Delhi (28°21′17–28°53′ latitude and 76°20′37″–77°20′37″ longitude) is situated 160 km South of the Himalayas, at altitudes from 213.3 m to 305.4 m above mean sea level. It is bounded by the Thar-Desert of Rajasthan in the West and plains of central India in the South. The megacity extends over 1,483 km2 with the present population of ~18 millions relative to ~3.5 millions in 1970. The entire northern part of India, especially Indo-Gangetic Plain, experiences a thick foggy weather during winter coupled with lower mixing heights. Consequently, pollutants do not disperse or mix freely with the upper boundary layer and thus rendered visibility poor. The temperature decreases rapidly toward the end of October, and continental air masses rich in pollutants pass over Delhi during winter. Winds are predominantly Westerly or North-Westerly during winter and Easterly and South-Easterly in monsoon. Besides numerous domestic coal burning units and three thermal power plants with the combined capacity of 1,087 MW operating in different parts of Delhi, vehicular and industrial emissions are major sources of air pollutants.
Daily monitored PM10, CO, NO2, and SO2 data at Income Tax Office in central part of Delhi are retrieved from CPCB web site (http://www.cpcb.nic.in) for January, 2007 to December, 2008. A thermal power plant (747 MW) is located within 500 m in the southeast direction of this site. Rainfall, temperature, RH, and wind speed data are collected from the India Meteorological Department (http://www.imd.gov.in).
Measurements of PM10, PM2.5, and PM1 were carried out with a GRIMM aerosol spectrometer (Model 1.108: OPC, GRIMM Inc.) at about 15 m above the ground level, on the rooftop of Indian Institute of Tropical Meteorology (IITM) building located in the central part of Delhi during Deepawali of 2007 and of 2008. This site primarily is a residential area away from the large pollutant-sources. GRIMM aerosol spectrometer is specifically designed for monitoring PM10, PM2.5, and PM1 aerosols. The technology enables to make precise cut off diameters for all the three PM sizes. This system allows collection of all three PM fractions simultaneously without any necessity of changing sampling heads. The particle analyzer was operated continuously a day before, on, and after Deepawali festivals for 2 days. A constant flow rate 1.2 liter/min was maintained throughout measurements.
3 Results and discussion
3.1 Temporal variation of PM10 concentrations
3.2 Relationship between of PM10 and gaseous pollutants
Pearson correlation coefficients between PM10 concentrations and concentrations of gaseous pollutants
3.3 Regression analysis between PM10 and meteorological parameters
3.4 Variation of PM10, PM2.5, and PM1 concentrations during Deepawali festivals
Ambient aerosol levels at various locations during Deepawali 2004, 2005, 2006, 2007, and 2008 [Residential (R); Industrial (I)], CPCB (http://www.cpcb.nic.in) Range for Delhi (Present study)
Ambient aerosols mass (μg m−3)
B.S.Z Marg (ITO) (R)
Ashok Vihar (R)
Shahazada Bagh (I)
Range for Delhi
Long-term data (January, 2007 to December 2008) revealed that PM10 concentrations at Delhi varied between 42 and 200 μg/m3 with an annual mean of 114.1 ± 81.7 μg m−3. PM10 (221 μg m−3) is 4 times higher than NAAQ Standard (PM10 = 60 μg/m3) during winter, one and half times higher (90 μg/m3) during summer and lower during monsoon (<60 μg/m3). These seasonal patterns in PM10 are due to emissions from fireworks during Deepawali (winter), windblown dust in summer and effective aerosol scavenging by extensive rain during monsoon. Inverse correlations of PM10 with temperature (−0.53), wind peed (−0.35), and rainfall −0.5) support the seasonal variation patterns.
Short-period averages of PM10, PM2.5, and PM1 concentrations over Deepawali days were 723, 588, and 536 μg/m3 of 2007 and 501, 389, and 346 μg/m3 of 2008. Further, in general, highest PM10, PM2.5, and PM1 levels were observed at 2000 h (on Deepawali day) and at 0500 h (on the next day). The mean CO, NO2, O3, and SO2 concentrations were 2,400, 95, 40, and 19 μg/m3, respectively. Among gaseous pollutants, NO2 and CO levels were frequently remained higher than the permissible limit of NAAQ (viz., 80 and 2,000 μg/m3 annual standards for NO2 and CO). Short-term and long-term exposure to high levels of PM10, PM2.5, and PM1 particles could cause health and environmental problems.
PM1 and PM2.5 are hazardous to cardiovascular and respiratory syndromes in most polluted megacities as a result of dense vehicular traffic and extreme firework episodes in India (Deepawali festivals). Exceedance of PM1 and PM2.5 beyond NAAQ standards during firework episodes is exacerbating health problem in Delhi. Rough estimates of inhaled particles show 37% deposition of total PM1 within respiratory system on Deepawali and the day after.
To sum up, maximum pollution levels occur during winter while minimum during monsoon. Winter, therefore, has greater exposure risk as pollutants often get trapped in lower layers of the atmosphere thereby leading to higher pollution levels.
Authors express sincere gratitude to Prof. B. N. Goswami, Director IITM, Pune and Dr. P. C. S. Devara, Head, PM&A for encouragement. Thanks are also to CPCB and IMD, India for providing data of gaseous pollutants and PM10 and meteorological variables.