Introduction

Cremation is a customary ritual performed by Hindus, Jains, Buddhists, and Sikhs as a part of ancient rite to purify the soul from the defunct body across the globe. In the process, as a part of religious beliefs, the deceased is honored by washing its body with honey, ghee, and milk and anointing its head with sandalwood oil. Furthermore, the body is subjected to funeral pyre as offering to the god of fire to free the astral body and leading it to a better life (Arnold 2016). However, scientifically, cremation is an incineration process wherein the corpse/human body is subjected to high temperatures to reduce them to ashes, thereby becoming a considerable source of air pollution (Santarsiero et al. 2005; Decker Junior et al. 2018; Cui et al. 2021). Respecting the religious sentiments regarding these funeral practices, the air quality governance has come up with cremation-related acts in different countries like United Kingdom (UK), United States (US) Australia, Canada, and South Africa as environmental safeguards (Lesile Banks 1938; National Health Act 2003; EPA 2005, 2016; O’Keeffe 2020). In 2008, Stockholm Convention came up with best crematoria practice guidelines considering crematoria installation design (with 850°C minimum furnace temperature, pre-preparation (for example, removal of metal and chlorinated compounds), use of cleaner fuel (gas based or electricity based), and combustion and process-based control technologies such as sealed furnace with heat recovery systems; fabric filters; activated carbon injection; etc. (UNEP 2008). These acted as quintessential measures for countries around the globe. In alignment to this, several other precautionary actions have been proposed by different developed countries. In UK’s statutory guidance for crematoria, these are calculations of suitable chimney heights for gaseous release and avoidance of melamine and PVC usage in coffin constructs (DEFRA 2012). In Australia, complete combustion and installation of wet scrubbers, bag filters, and honeycomb-designed selenium catalytic filters are suggested (SEWPAC 2011). However, in Europe, the focus is on efficient burner design, selenium salts for mercury removal, and greener fuels with low sulfur content like natural gas and replacement of conventional wood containers with fireboards/clothed fireboards (EEA 2019).

The cremation procedure of human cadavers contributes substantially to the air pollution load leading to the simultaneous emissions of particulate and gaseous pollutants in the ambient air (Korczynski 1997; DEFRA 2012; Da Cruz et al. 2017; Xue et al. 2018; ARAI and TERI 2018). However, due to the associated beliefs, cultural sentiments, and governance, the studies quantifying such an aspect in detail are scarce. The relative emission contribution of any cremation site is largely influenced by the number of cremations, crematorium design, fuel throughputs, and the installed emission control devices (O’Keeffe 2020). To ascertain the consequential effect of these variables, PM2.5 concentrations have been studied by González-Cardoso et al. (2018) at 40 crematoria in Mexico. Similar study has been conducted by Xue et al. (2018) at 9 cremators for particulates, gaseous pollutants, and VOCs in Beijing, China. Furthermore, though crematoria is considered small-scale installations, yet their impact at local-level/immediate surroundings is considered significant, especially the exposure to the working personnel (Mari and Domingo 2010; Green et al. 2014). Unlike developed nations, developing countries like India lack such legislative measures for siting of cremation sites adversely impacting the human health.

In India, the registered deaths witnessed an increase of 26.4% from year 2011 to year 2019. The indifferent increase in the death rates over the decade proliferated the need of registered crematoria for Hindu, Jain, and Sikh religious cremation rituals (Vital Statistics of India 2019; TERI 2021). Subsequently, the subject matter emerged as a key challenge for air quality regulators in optimizing micro-level air quality improvement plans owing to the continuous emissions. In one of the national-scale studies conducted by TERI ( 2021) for emission estimates in India, crematoria is known to account 47,000 tons/year of PM10, 23,000 tons/year of PM2.5, 6000 tons/year of NOx, 1000 tons/year of SO2, and 235,000 tons/year of CO from whole country. However, in city-specific studies, Sharma and Dikshit (2016) estimated 126 tons/year of PM10, 114 tons/year of PM2.5, 35 tons/year of NOx, 12 tons/year of SO2, and 777 tons/year of CO from crematoria for years 2013–2014 in Delhi in North India while for year 2016, ARAI and TERI (2018) reported the emissions as 200 tons/year of PM2.5, 100 tons/year of NOx, and 2200 tons/year of CO emissions. In another study in Kolkata, eastern India by NEERI (2020), the emission load was found to be 13.2 tons/year for PM10 and 9 tons/year for PM2.5 which is comparatively very less than Delhi. Similar emission inventories have been developed for cremation practices for different cities such as Pune city (Western India) by Beig et al. (2017) and ARAI (2010), Kanpur city (Northern India) by Behera et al. (2011), Ahmedabad city (Western India) by Beig et al. (2020), and Chennai city (Southern India) by CPCB ( 2010).

In brief, it can be elucidated that small area sources like crematoria might not hold a significant sectorial share in the total air pollution load at city scale; however, these act as a potential threat at local/micro-level. The heterogeneity in the spatio-temporal patterns of the emissions in synergy with the prevailing wind directions further creates challenges in ascertaining the potential area of interest for likely exposure. The present article is thus an attempt to address one such localized source, i.e., crematoria. In view of the same, the study estimates the emission load from the current registered crematoria sites taking NCT of Delhi, India, as the reference city. Furthermore, based on the number of cremations, detailed investigation of a selected crematorium has been done for delineating the air quality impact zone. The study also briefs the zoning criteria for siting of cremation site followed in different countries to aid policy makers in establishing similar site selection criteria for countries like India as well.

Materials and methods

Study area

Delhi, the capital city of India, hosts a population of 16.9 million (Census 2011) over 1483 km2 area. Of the total population, 81.68% are Hindus, 12.86% are Muslims, 3.40% are Sikhs, 0.99% are Jains, 0.87% are Christians, 0.11% are Buddhists, and 0.09% are from other religions. In 2019, Delhi witnessed a total of 145,284 total deaths (Vital Statistics of India 2019). Being largely dominated by Hindus, ritualistic cremation ceremony is the common phenomenon for the human remains of the deceased. Considering the religion data, 13.73% of the population follows inhumations while the rest 86.27% follows cremation practices for disposing the human cadavers (excluding those below 5 years of age). There are 51 registered crematoria across NCT of Delhi wherein Nigambodh Ghat owes the maximum number of cremations per day. The district-wise distribution of the cremation sites is summarized in Table 1. Furthermore, the cremation sites in Delhi are known to operate on different fuel types, i.e., cow dung, wood, and CNG. A few sites are electric based as well. The fuel-category-wise distribution of these is presented in Fig. 1. An existing conventional pyre design for the cremation practices in India is shown in SI, Fig. S1.

Table 1 District-wise details of crematoria and their fuel requirements
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Fig. 1
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Map showing distribution of crematoria and their fuel requirements in NCT of Delhi

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Methodology

The study defines a methodology for estimating air pollutant emission load from cremation practices and delineating the air quality impact zone for likely exposure within a city. The methodology includes mapping of locations of registered cremation grounds on Google map and its verification on ground through physical visits. The open-ended questionnaire survey has been prepared for collection of data considering the type of crematorium, fuel type used, fuel quantity requirements, and number of cremations (SI, Fig. S2). The data has been collected for 23 sites in person at each site’s office (SI, Table S1). The data is authentic and accurate. However, some sites have not been surveyed (28 in nos.) in physical and collected the information through telephonic conversations. Furthermore, the fuel consumption rate for these non-surveyed sites has been incorporated from the surveyed data. However, for the number of cremations/day at these 28 sites, data has been acquired from authentic/reliable secondary database (government sites/Economic Handbooks such as Census 2011; Vital Statistics of India 2019). The total death rate has been used to spatially distribute the bodies of the deceased at different cremation sites based on the population following the said rituals. The multi-pollutant emission inventory has been then developed for the whole city considering PM2.5, NOx, SO2, and CO using Eq. (1). Moreover, certain toxic and harmful pollutants like VOCs, organics like polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and polycyclic aromatic hydrocarbons (PAH), and heavy metals like mercury are also released from cremation rites; however, they have not been studied considering the importance of criteria pollutants (DEFRA 2012; EEA 2019; O’Keeffe 2020). The pollutant, body, and fuel-specific emission factors have been reviewed comprehensively and suitably adopted in the present study. Based on the developed emission inventory, Nigambodh Ghat cremation site has been selected in view of the maximum cremated bodies in a day. For the selected site, air quality prediction has been carried out using dispersion modelling for delineating the zone of influence for likely exposure. Considering the impact in the immediate surroundings, further, several localized interventions have been proposed for managing air quality at micro-scale. The process flow chart followed in the present study is shown in Fig. 2.

$${E}_{j=\kern0.5em }\sum\nolimits_{c=1}^n\Big({N}_c\ast {EF}_{body,j\Big)}+\left(\Sigma\ {N}_c\ast {Q}_f\ast {EF}_{f,j}\right)/1000$$
(1)
Fig. 2
figure 2

Methodology adopted in the present study

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where Ej  is emission load estimated for pollutant “j” in kg/day, c = 1 to n are cremation sites, Nc are number of bodies burnt/day, EFbody, j) is emission factor of the body in g/body for pollutant “j,” Qf is the quantity of fuel type “f” required in kg per body, EFf, j is emission factor for fuel type “f” for pollutant “j” in g/kg. Furthermore, the input data for the application of the equation has been summarized for Nigambodh Ghat site in SI, Table S2.

Emission load estimation in Delhi

The emission inventory of the registered crematoriums has been developed by collecting fuel requirement data and average bodies burnt at 23 sites in different districts of Delhi (Fig. 1). The different fuel types used for these practices were found to be wood, half steam (different pyre design based on wood fuel), CNG, and cow dung with the average consumptions being in the range of 300–500 kg/body, 200 kg/body, 12 kg/body, and 150 kg/body, respectively. Half steam is a type of pyre based on wood fuel in which body is kept at certain height (approximately 0.5 m from ground). The quantity of wood required per body is approximately 50% of the conventional one. Furthermore, after identifying the type of crematoria and cremations in a day at non-surveyed sites through secondary database (Census 2011; Vital Statistics of India 2019), emissions have been estimated at all the sites. Based on the distribution of the crematoria, district-wise emission load has been estimated for four pollutants, PM2.5, NOx, SO2, and CO using Eq. (1) and reviewed emission factors (SI, Table S3). The findings of which are summarized in Table 2.

Table 2 Pollutant-wise estimated emission load at the crematoria in different districts of NCT of Delhi
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The maximum emission load has been estimated from Central district followed by South, North West, and West districts contributing 242 kg/day, 156 kg/day, 144 kg/day, and 118 kg/day of PM2.5, 91 kg/day, 56 kg/day, 51 kg/day, and 43 kg/day of NOx, 18 kg/day, 11 kg/day, 10 kg/day, and 9 kg/day of SO2 while 1644 kg/day, 1061 kg/day, 982 kg/day, and 805 kg/day of CO. The maximum contribution from Central district is due to the Nigambodh Ghat wherein about 60 bodies are being cremated on daily basis, South Delhi cremating 38 bodies/day at 12 sites, North West Delhi cremating 34 bodies/day at 6 sites, and West Delhi cremating 29 bodies/day at 5 sites. The minimum emissions were estimated at North East district with 15 kg/day of PM2.5, 6 kg/day of NOx, 1 kg/day of SO2, and 100 kg/day of CO attributable to a single crematorium witnessing 4 cremations/day. The district-wise emission load of these pollutants is presented in Fig. 3.

Fig. 3
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District-wise spatial distribution of pollutant emissions from crematoria in NCT of Delhi. Note: Color code represents relative grading scale, green color denoting the lowest values while dark red color denoting the highest values

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Furthermore, for whole NCT of Delhi, crematoria activities (due to fuel and human body) are found to contribute 1075 kg/day (393 tons/year) of PM2.5, 388 kg/day (142 tons/year) of NOx, 78 (29 tons/year) kg/day of SO2, and 7359 kg/day (2686 tons/year) of CO. The emissions due to average number of bodies cremated at all the sites are observed as 8 kg/day (1%) for PM2.5, 219 kg/day (56%) for NOx, 30 kg/day (38%) for SO2, and 37 kg/day (0.5%) for CO. However, the emissions due to fuel requirement were found to be 1067 kg/day for PM2.5, 169 kg/day for NOx, 48 kg/day for SO2, and 7322 kg/day for CO. The estimated emissions are comparatively higher (1.5–2 times) as compared to those estimated by researchers in the past. This could be attributed to the fact that the average fuel requirements and the bodies burnt per day taken for emission calculation were obtained for the respective study periods and by conducting surveys at few locations only in the previous studies. However, the present study used the data based on the survey at more than 45% of the sites. Moreover, the total death rates have witnessed a tremendous increase over the years (Directorate of Economic and Statistics 2019).

Air quality impact zone assessment through modelling around selected crematoria

Model domain set-up

The study has used AERMOD, a USEPA recommended model for regulatory purposes, for air quality impact prediction to delineate the zone of influence at a selected crematoria. The Nigambodh Ghat cremation site has been selected based on the maximum number of bodies burnt in a day to address the likely maximum contribution. The site has been selected to evaluate the air quality impact zone that could suggest the crematorium site selection criteria. The default regulatory setting considering flat terrain and urban area dispersion coefficients has been used for model set-up. The emissions calculated for the selected cremation site along with the meteorological data of Delhi have been used as the input parameters (SI, Table S4). The meteorological data has been considered for most critical month for year 2019, i.e., January (low atmospheric dispersion potential). The surface and upper air meteorological data have been processed from Weather Research Forecast (WRF) model for Central Delhi location. The average wind speed was found in the range 0.50–2.10 m/s with winds blowing dominantly from WNW-NW direction (SI, Fig. S3). Furthermore, the relative humidity and ambient temperature were found in the range 9–29 °C and 9–79%, respectively. Since the crematoria is operational from 7:00 am to 6:00 pm in winters, the data and the model run have been done accordingly. Furthermore, the receptor grids have been used at an interval of 50 m cell size with total number of grids as 201 × 201 = 40401 number of grids and the total length in x and y direction is 5 km each.

Air quality impact prediction at Nigambodh Ghat site

The emission from different activities impacts the ambient air quality in its surrounding at certain distance, pre-dominantly in the downwind side (dominant) which varies from season to season. The contribution of pollution emission from crematoria has been predicted at different downwind distances, i.e., GLC during the study period at 10 m to 5 km. The contribution has been predicted at the selected site, Nigambodh Ghat, both, considering a single pyre and entire cremation ground. The air quality has been predicted considering 1- and 24-h concentrations for a single pyre and entire cremation ground. Furthermore, the impact zone has been considered based on the distance from crematorium where contribution was found to be ≥ 3 μg/m3 for PM2.5, ≥ 4 μg/m3 for NOx and SO2, and ≥ 100 μg/m3 for CO, i.e., 5% of daily average NAAQS values of 60 μg/m3 for PM2.5, 80 μg/m3 for NOx and SO2, and 10% of 8-h average NAAQS value of 2000 μg/m3 for CO, respectively.

Single pyre

Considering the importance of the buffer zone for setting a cremation site, an in-depth investigation was further done to delineate the zone of influence of a single pyre that takes ~2.5–3 h for one body’s cremation process. For PM2.5, the 1- and 24-h maximum GLCs were 7058 μg/m3 and 321 μg/m3 which reduced to ≤ 3 μg/m3 at 2 km and at 500 m distance in downwind side, respectively. For NOx, these values were 2296 μg/m3 for 1 h and 104 μg/m3 for 24 h which became negligible beyond 1 km and 500 m in the respective cases. For SO2, the maximum 1-h GLC of 468 μg/m3 reduced to 4 μg/m3 at 500 m while for 24-h, the maximum GLC of 21 μg/m3 reduced to <4 at μg/m3 at 100 m. Similar observations were made for maximum 1- and 24-h GLCs of CO which reduced to <100 at 1 km and 500 m in the respective cases (Table 3). Thus, considering the 24-h averages, the contribution at 500 m was found less than the 5% of daily average NAAQS for PM2.5, NOx, and CO while 100 m for SO2, respectively (Fig. 4).

Table 3 Assessment of zone of influence for a single pyre on ambient air quality
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Fig. 4
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Isopleth showing 24-h predicted pollutant concentrations during January from a single pyre

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One day cremation activities at Nigambodh Ghat

The air quality has been assessed for 1- and 24-h time averaging periods for likely impact during a single cremation activity, all the cremation activities conducted in a day and after the maximum dispersion and dilution under the influence of prevailing meteorological conditions. The details of which are shown in Table 4.

Table 4 Assessment of air quality impact zone of Nigambodh Ghat crematorium
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For PM2.5, the 1- and 24-h maximum GLCs were 21890 μg/m3 and 3224 μg/m3 which reduced to ≤ 3 μg/m3 at 3 km and 1 km distance in downwind side. For NOx, these values were 7668 μg/m3 for 1 h and 1129 μg/m3 for 24 h which reduced to ≤ 4 at 2 km and 1 km in the respective cases. For SO2, the maximum GLC of 1167 μg/m3 and 173 μg/m3 reduced to 4 μg/m3 beyond 2 km and 500 m for 1- and 24-h averages. Similar observations were made for maximum GLC values of CO for 1 h (166740 μg/m3) and 24 h (24560 μg/m3) which reduced to <100 at 3 km and 1 km in the respective cases. Thus, considering the 24-h averages, the contribution at 1000 m was found less than the 5% of daily average NAAQS for PM2.5, NOx, and CO while 500 m for SO2, respectively (Fig. 5).

Fig. 5
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Isopleth showing 24-h predicted pollutant concentrations during January at Nigambodh Ghat cremation site

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Source-specific policy measures

The study also addressed the public perception for the possible impacts of crematoria activities on their lifestyle by surveying the individuals residing within 1 km of the premises boundary. The survey has been conducted near 23 cremation grounds. About 61 families have been surveyed using open-ended questionnaires as shown in SI, Fig. S4. These families were asked to get their perception regarding the awareness about cremation emissions, odor and smoke visibility, respiratory issues, eye irritation, and cardiovascular problems. Most of the surveyed families had limited knowledge of the subject. Furthermore, based on the findings, it is observed that smoke and odor are being felt by resident around cremation sites (as responded by ~50% of the surveyed people). However, the after-effects did not lead to any chronic respiratory or cardiovascular diseases; however, eye irritation was the common ailment (experienced by ~25 families; 41% of the total surveyed population), especially at cremation sites where comparatively higher number of bodies were burnt and were located in the vicinity of the habitable areas. Satnagar Cremation ground, Nigambodh Ghat were such sites where 7 and ~60 bodies were cremated on an average basis and the consequential effects were reflected in the public opinion. Also, the surveyed data in the study provided only the glimpse of general public opinion and did not consider the critical assessment of health impacts and thus, other acute/chronic diseases could also be experienced.

Considering the predicted air quality impact zone and the conformity of the impacts on the immediate residents in the downwind direction of the cremation site, the study proposes and prioritizes certain control measures in view of the operational process, fuel requirement, and the associated cost investments. The details of which are given below.

Control strategy 1 (CS1): Change in design of pyre - Considering the funeral practices followed since ancient times, a change in design of pyre has been suggested by increasing the height of the bench for pyre preparations which enhances the combustion efficiency and accordingly reduces the average wood requirement per body (from average 396 to 200 kg/body) (NEERI 2019). The measure has been adopted from the already existing pyre design at Nigambodh Ghat, which is rarely followed by the people. Thus, if implemented at all the 46 wood-based cremation sites, the emission will reduce from 1064 to 605 kg/day for PM2.5, 168 to 96 kg/day for NOx, 47 to 27 kg/day for SO2, and 7252 to 4125 kg/day for CO. The dispersion potential is generally high for this elevated pyre design compared to ground-based conventional design.

Control strategy 2 (CS2): Install air pollution control device in conventional pyre/with modified pyre design - In this measure, a hood and a duct with venturi scrubber are suggested to be installed as air pollution control device at the shed of the pyre. Hood covers the surface area of the gaseous release while the duct transfers the release to venturi scrubber for effective removal of dust and gaseous pollutants (NEERI 2019). Thus, due to the installed air pollution control technology, emissions are considered to be reduced by ~65% for both particulates and gases. The implementation of measure, however, requires additional cost for the installation of the same (NEERI 2019). Furthermore, release of high-temperature smoke from chimney hood further increases the dispersion and reduces the impact.

  1. a.

    Conventional pyres (CS2.1): In conventional pyres, the air pollution control devices are proposed to be installed at existing pyres which reduces gaseous and particulate emissions by 65% (NEERI 2019).

  2. b.

    Modified pyre design (CS2.2): In modified pyre design, the control technology is proposed to be deployed at the new pyre design (as described in CS1) with 200 kg/day of wood consumption.

Control strategy 3 (CS3): Replace conventional wood-based pyres with CNG-based facilities - The replacement of the existing wood-based practices is proposed which will bring down the emissions to 30 kg/day for PM2.5, 82 kg/day for NOx, and 452 kg/day for CO as compared to base case, i.e., 1064 kg/day, 168 kg/day, 47 kg/day, and 7252 kg/day, respectively. However, the installation of the entire set-up would require huge infrastructural, operation, and maintenance costs.

Control strategy 4 (CS4): Development of green barrier around the premises of the crematorium - This is suggested in view of the air pollution tolerance index of several evergreen plants in capturing gaseous and particulate pollutants (Kapoor and Chittora 2016; Barwise and Kumar 2020). The selection of plant species that can be planted as a part of green belt/green infrastructure depends on adsorption, absorption, metabolization, and accumulation of toxic air pollutants (Das and Prasad 2012; Kapoor and Chittora 2016). In the measure, a green barrier consisting of evergreen trees is suggested to construct in the 200 m radius area around the single pyre and entire cremation ground to ascertain its impact on the ground level concentrations. Furthermore, considering the Indian tropical conditions and the reviewed studies conducted in similar domain, these plants can be Arjun, Morus, Ashok, and Neem (Gupta et al. 2016).

Furthermore, to evaluate the impact of aforementioned control strategies on the pollutant concentrations, simulations have been done considering a single pyre and Nigambodh Ghat (60 pyres) for the most critical pollutant, PM2.5 (as described in Tables 3 and 4). The simulations have been done considering 24-h concentrations. The details of which are given in Table 5. Based on the summary of the findings, it can be inferred that significant reduction can be achieved by replacement of existing wood practices with CNG-based facilities (CS3), being 96% for single pyre and 90% for multiple pyres followed by installation of air pollution control device at modified pyre design (CS 2.2), i.e., 88% reduction for single pyre and 85% for multiple pyres. The conventional pyre design (CS2.1) can be reduced at about 65% in both cases. Furthermore, minimum reduction has been observed for development of green barrier, being 45% for single pyre and 21% for multiple pyres.

Table 5 Evaluation for proposed control strategies w.r.t PM2.5
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Assessment of zone of influence for cremation site selection

Due to the likely impact of smoke and resulting emissions as detailed above, a review of siting criteria for crematorium has been done for delineating the buffer zone. It is observed that the air quality impact zone predicted by air quality modelling in the present study is comparable to the ones prescribed in the legislations of different countries as summarized in Table 6. The zoning criteria have been set for different land-use types in different countries with residential as sensitive areas, being the prime focus in view of the potential effects that can be caused in the close proximity.

Table 6 Review of site selection criteria for cremation ground in different countries
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The studies/policy guidance reports were reviewed for countries like UK, Australia, South Africa, California, and Canada. It is observed that a common criterion was defined for site selection irrespective of air pollution impact. Furthermore, safe distance near the residential areas was prescribed as 183 m in UK, 152 m in California, and 20–70 m in Canada while a 200–300 m distance was demarcated for a sensitive area in Western Australia and 500 m zone for agricultural/residential areas in South Africa. Moreover, in Southern Australia, a 150 m safe distance was stated irrespective of the pollutant and land-use type (Lesile Banks 1938; National Health Act 2003; EPA 2005, 2016; O’Keeffe 2020).

Similarly, in the present study, a buffer/air quality impact zone has been demarcated considering different pollutants based on the analysis discussed in the “Air quality impact prediction at Nigambodh Ghat site” section. The impact zone for a single pyre has been ascertained as 500 m while for multiple pyres with 60 cremations per day, it is 1000 m considering the most critical pollutant, i.e., PM2.5. Furthermore, an attempt has been made to re-assess the impact zone after the implementation of proposed measures. It is observed that on implementation, the buffer zone will reduce to 170 m for single pyre and 500 m for multiple pyres in CS1, 235 m and 40 m for single pyre while 750 m and 280 m for multiple pyres in CS2.1 and CS2.2, 50 m for single pyre and 300 m for multiple pyres in CS3 while 350 m for single pyre and 800 m for multiple pyres in CS4. This safe distance can further be minimized by increasing green belt area with dense canopy. Moreover, the delineated buffer zone has been ascertained based on winter month analysis, most critical month from air pollution point of view.

Conclusions

The present study attempts to critically understand the individual contribution of localized sources like crematoria. Furthermore, the study estimates the emissions from identified crematoria in NCT of Delhi considering both particulate and gaseous pollutants. The study further delineates the air quality impact zone for identification of minimum separation distance for exposure reduction. The study also suggests the control strategies for achieving better air quality levels at local-level/micro-scale. The summary of the findings is as follows:

  • A total of 51 crematoria have been identified in NCT of Delhi, of which 46 are wood-based, 2 are wood and CNG-based, 2 are electric, and 1 is dung-based site.

  • The average fuel requirement is found to be 300–500 kg/body for wood (396 kg/day on average basis), 200 kg/body for half-steam, 12 kg/body for CNG, and 150 kg/body for cow dung.

  • Crematoria is found to contribute 1075 kg/day (393 tons/year) of PM2.5, 388 kg/day (142 tons/year) of NOx, 78 (29 tons/year) kg/day of SO2, and 7359 kg/day (2686 tons/year) of CO attributable to relatively higher wood-based fuel requirements.

  • Based on the distribution of the crematoria, central district witnessed maximum number of cremations and subsequently the emissions (242 kg/day of PM2.5, 91 kg/day of NOx, 18 kg/day of SO2, and 1644 kg/day of CO) attributable to the maximum number of cremations at Nigambodh Ghat location wherein bodies are bought from other districts as well.

  • The air quality impact zone has been delineated based on the distance from crematorium where contribution was found significant. For a single pyre–based site (1 body per day), the buffer zone was found to be 500 m and for multiple pyres (60 bodies per day), it was 1000 m.

  • The simulation result of control strategies indicated the significant reduction can be achieved by replacement of existing wood practices with CNG-based facilities, being 96–90% followed by installation of air pollution control device on modified design (85–88%). Further development of green belt also reduced the pollution by 21–45%. These control strategies further reduced the zone of influence of the crematoria.

  • In addition to the quantified prevention and mitigation techniques, other measures like installation of stack and adoption of electric cremation can also be the option for reduction of emission from the cremation activities.

The study provides an updated useful database on the crematoria activities in NCT of Delhi, related emission load estimation, and highlights the issues of local air pollution which nearby resident faces. Furthermore, the demarcated zone and proposed interventions in the study can aid air quality regulators in establishing site selection criteria for siting of cremation grounds as environmental safeguards keeping in view the associated beliefs and cultural sentiments.