Air quality of megacities such as Delhi is of serious concern due to its high pollutant concentrations and resulting serious health hazards, making it an important issue to current environmental researchers (Kumar, Chandra Gupta, & Singh Parmar, 2014; Paschalidou & Kassomenos, 2004). People residing in urban areas are often exposed to a complex mixture of environmental pollutants due to heterogeneous and spatial distribution of emission sources and prevailing meteorological conditions. Certain predetermined patterns associated with the local meteorological conditions of urban air pollution episodes have also been reported (Singh et al., 2010). Further, episodes of short-term air quality degradation significantly affect human health and have long-term negative impacts, which are drawing the attention of the scientific community (Nastos, Paliatsos, Anthracopoulos, Roma, & Priftis, 2010; Pope et al., 2002; Samoli, Nastos, Paliatsos, Katsouyanni, & Priftis, 2011).
Diwali is one of the major festivals that is celebrated with great fervor across India in the months of October and November. Firecrackers bursting during this festival are an integral part of the festivity. Fireworks are reported to emit trace gases, particulates, and metals into the atmosphere, which generate dense clouds of smoke containing potassium nitrate, sulphur, and several other trace elements, which severely affects the environment as well as human health (Drewnick, Hings, Curtius, Eerdekens, & Williams, 2006; Dutcher, Perry, Cahill, & Copeland, 1999; Dwivedi, Tripathi, & Shashi, 2008; Hirai, Yamazaki, Okada, Furuta, & Kubo, 2000; Kulshrestha, Nageswara Rao, Azhaguvel, & Kulshrestha, 2004; Liu, Rutherford, Kinsey, & Prather, 1997; Mandal, Sen, & Sen, 1997; Ravindra, Mor, & Kaushik, 2003; Tripathi & Gautam, 2007). Concentrations of these pollutants depend on the composition of the fireworks and sparklers (Barman, Singh, Negi, & Bhargava, 2009).
Worldwide, researchers have reported the effect of firework activities on the air quality with particulate matter, its components, and often trace gases during various festivals such as the Lantern Festival in China (Wang, Zhuang, Xu, & An, 2007), Independence Day in the U.S. (Liu et al., 1997), and New Year's (Drewnick et al., 2006).
In India, a few groups have reported degradation of air quality due to firework activities during Diwali festival. Kulshrestha and coauthors (2004) reported a high level of different trace elements in ambient air of Hyderabad, India, due to fireworks. Ravindra and coauthors (2003) observed an increase of 2-10 times in concentrations of [PM.sub.10], total suspended particulates, nitrogen dioxide (N[O.sub.2]), and sulfur dioxide (S[O.sub.2]) in the city of Hisar, India, during Diwali. Barman and coauthors (2009) noticed a remarkable increase in [PM.sub.2.5] concentration in the city of Lucknow, India. Apart from the joy provided by the splendid scenes of multicolored lights in the sky and the excitement of resounding firecracker detonations, the burning of fireworks is a source of airborne pollutants, including trace metals and ozone ([O.sub.3]).
Several studies have reported a fireworkrelated increase in the concentration of surface ozone in Delhi (Attri, Kumar, & Jain, 2001; Ganguly, 2009). Fireworks emit airborne particles consisting of various elements, including aluminum (Al), barium (Ba), cadmium (Cd), copper (Cu), potassium (K), and manganese (Mn), as well as other heavy metals that are deleterious to human health (Moreno et al., 2007; Ravindra et al., 2003; Vecchi et al., 2008). Hirai and coauthors (2000) observed that inhalation of smoke from fireworks can cause cough, fever, and dyspnea, and lead to acute eosinophilic pneumonia. Short-term elevated emissions of trace elements from fireworks can also trigger several health problems in humans such as neurological and hematological effects. The aesthetic of the lighting of firecrackers and sparklers, along with the noise, seem essential and appropriate to the Diwali festival. The use of colored sparklers by children at ground level, however, can put them at a severe exposure of inhaling the resulting pollutants.
The purpose of this study was to compare the concentrations of particulates and metals with other similar studies conducted in various cities across India around the times of Diwali. The air quality variations during Diwali were monitored for 2 consecutive years (2012 and 2013) with a short-term sampling program during Diwali festival (November 10-16, 2012, and October 31-November 6, 2013) at different residential locations in Delhi. Overall, we attempted to assess the additional burden on air quality due to the Diwali festival held in Delhi, where air pollution is an acute problem throughout the year.
This study aimed to understand the shortterm changes in air quality during the Diwali festival and its comparison with air quality data from previous years. The study provides useful information regarding the changes that occurred in air quality during 2 consecutive years (2012 and 2013).
Materials and Methods
Study Site and Sample Collection
The national capital territory of Delhi (28[degrees]38' N and 77[degrees]20' E, 216 m above mean sea level) occupies an area of 1,483 [km.sup.2] and has a population of nearly 14 million as per the Census of India. The Central Pollution Control Board (CPCB) of India has identified the city of Delhi as one of the most polluted urban areas in the country (and in the world in terms of air pollution). The sampling site, East Delhi (28[degrees]48.01' N; 77[degrees]17.00' E), is located in the Trans-Yamuna area. In the east, the sampling site is surrounded by the border of Uttar Pradesh, comprising the cities of Noida and Ghaziabad. The sampling site has an elevation of 239 m above sea level. East Delhi has a population of 1,448,770 (2001 census) and an area of 64 [km.sup.2], with a high population density of 22,638 persons/[km.sup.2.]
The monitoring station was chosen on the terrace of a 3-story private building in a densely populated residential area at the outside zone of influence of other sources located within the designated zone for the monitoring. The sampling was carried out in accordance with CPCB guidelines. The terrace was chosen for sampling because the nearby houses have roof spaces that are used by residents for the firework display. No major industrial sources are located within 5 km around the site.
Sampling of [PM.sub.10] and [PM.sub.2.5] was conducted on the rooftop of the private building (approximately 12 m above ground level). The sampling site of the rooftop was maintained at a suitable distance from any other direct pollution source, including traffic. The nearby buildings in the sampling zone were of similar heights and the sampler was kept away from any obstructions to airflow. In addition, this height can be considered as the respirable zone for people in 2- and 3-story buildings.
In order to study the temporal variation in distribution and...