Spatiotemporal Trend of Hazardous Waste Sites and Risks in Urban Jakarta, Indonesia

Abstract

Urban areas are characterized by growing populations and industrial and economic sectors. This leads to trends of increasing hazardous wastes. The aim of this study was to evaluate the trends of hazardous waste risks in several districts in urban Jakarta for the years 2021 and 2022. The results confirmed that, from 2021 to 2022, there were increases in hazardous-waste-producing sites and particular sectors, and decreases in the amount of hazardous waste produced. From 2021 to 2022, the hazardous-waste-producing sectors increased by 55.96%, and the total hazardous waste amount across Jakarta decreased from 644,999.93 tons in 2021 to 521,036.75 tons in 2022. The hazardous-waste-producing sectors were mostly in North and East Jakarta, and there were trends of new hazardous-waste-producing sectors emerging in West and South Jakarta districts from 2021 to 2022. The hazardous-waste-producing sectors were dominated by the manufacturing sectors and emerging healthcare sector. From 2021 to 2022, the hazardous waste trends shifted from industrial to medicinal wastes, and the risks shifted from corrosive, explosive, and toxic to infectious risks. The risk levels of urban Jakarta based on hazardous waste risk scores fall into the medium levels. Based on the spatial statistical analyses, Moran’s I, and LISA, the hazardous waste sites and high amounts of waste in 2021 tended to be clustered in North, East, and West Jakarta, while in 2022, this cluster tended to be dispersed.

1. Introduction

Waste that has potentially poisonous, flammable, corrosive, or reactive qualities is classified as hazardous waste [1]. Because of its quantity and concentration, combined with physical and chemical properties that might lead to illnesses and a markedly elevated mortality rate, hazardous waste may pose a risk to human health. Additionally, if it is not adequately handled, it may potentially be hazardous to the environment [2]. Risk assessment is required to establish risk priority, which can assist decision-makers in identifying any potential risk management measures [3]. This is necessary in order to find the best management for hazardous waste in each context. Industries that use heavy metals in their operations, like the electronics, painting, metal fabrication, and automotive sectors, are among the primary producers of hazardous waste. Hazardous waste is also generated by industries that manufacture petroleum, combustible parts, organic solvents, nuclear reactors, and volatile chemicals [4]. Every business sector produces a wide variety of hazardous waste kinds. A total of 148 of the 3000 hazardous substances that are now produced and used in China have been classified as extremely dangerous [5]. With 2.63 million tons of hazardous waste produced, the base-metal industry in Spain was found to be the largest producer of hazardous waste in the country’s manufacturing sector. The chemical, pharmaceutical, rubber, and plastic industries came in second with 1.45 million tons. With 656,000 tons of hazardous wastes created in 2016 [6], the industries that produce computers, electronics, optical products, electrical equipment, and motor vehicles came in third place among those that produce the most hazardous waste. The production of chemicals and petroleum, both of which have an effect on the environment, was found to contribute the most to the industry’s total amount of hazardous waste. This sector accounts for 84% of the production of hazardous waste in the United States [7]. According to a Polish study, this industry’s hazardous waste contribution from 2016 to 2018 was 80.22% [8]. The manufacturing sector was the biggest contributor, accounting for 24% of Australia’s 8 million tons of hazardous waste produced between 2016 and 2017 [9]. Furthermore, according to a study on the Iranian petroleum industry, 73% of the chemical waste was dumped in sanitary landfills, while the industry produced over 160 dangerous chemicals [10]. Although having industry in an area does boost the local economy, it can also result in catastrophes known as industrial disasters, which are brought on by technological malfunctions. Unplanned infrastructure placement, particularly in industrial and warehousing facilities, in densely populated urban areas can put the surrounding communities at risk for fires, explosions, or the discharge of harmful substances [11]. In addition to injuring a large number of people both inside and outside the factory, these incidents will harm the surrounding environment as the hazardous waste spreads.

According to reports, 947 industries in Indonesia produced 60 million tons of garbage in 2021 [12]. Waste from a variety of raw materials used in manufacturing, especially toxic and hazardous wastes, has increased as a result of industrial activity and growth-related increases in industrial output [13,14,15]. In Indonesia, for regulating the hazardous wastes, the Government of the Republic of Indonesia has released Minister Regulation No. 101 of 2018 outlining guidelines for the recovery of hazardous and toxic waste-contaminated land. The regulations cover hazardous waste categories, the effects of contaminants on impacted individuals, hazardous waste management, the presence of provincial-level emergency response institutions for hazardous waste, and emergency programs. But there are not many distinctions between the two rules. For instance, the Ministerial Regulation does not contain the pathways, although the EPA does, and assessment is still required to determine the possibility of future or ongoing release and the migratory potential of the hazardous compounds [16]. In Indonesia, one of the urban areas generating hazardous wastes is Jakarta City. In this city, there are numerous industrial and commercial activities that have the potential to generate significant amounts of hazardous waste. Setiyono [17] reported that, in Jakarta, there are at least three sectors that have high potential to generate hazardous wastes including industrial, domestic, and health service sectors. In 2023, Wardianto et al. [18] confirmed that in one of the districts in Jakarta, that is, in West Jakarta, the amount of hazardous waste can reach up to 4334.85 kg/year.

Jakarta is an urban city experiencing urbanization and rapid growth, with 11.34 million people. This condition will lead to growing activities in industrial and other sectors and lead to the emission of hazardous wastes. Currently, there are knowledge gaps and limited information on hazardous material produced by particular activities in Jakarta. Without a proper, accurate, and detailed risk assessment, the impact of hazardous waste on the community will be unpredictable and proper mitigation actions cannot be taken, leading to possible huge impacts to the community. Hence, performing risk assessment is important to overcome hazardous waste disasters in Jakarta’s urban areas. This study, therefore, aimed to model a city/district-based risk assessment for each type of hazardous waste in Jakarta for anticipating hazardous waste disasters and necessary responses, with the development of identification parameters or elements of hazardous waste and toxic waste risk assessment as the study’s primary aspect of novelty. Furthermore, the risk and causes of risk in industrial disasters are also remodeled by categorizing the disaster, hazardous and toxic substances, and hazardous and toxic waste aspects. This study assessed the hazardous wastes in the years 2021 and 2022 to ascertain the hazardous waste trends. The novelty of this study is using spatial statistical analyses to provide a comprehensive spatiotemporal trend of hazardous waste sites and risks.

2. Materials and Methods

This research was conducted in DKI Jakarta Province. A cross-sectional design was used with data collected utilizing established databases, semi-quantitative risk analysis, risk assessment, and GIS-based hazardous waste risk mapping following Lestari et al. [19] and Zakianis et al. [20].

2.1. Study Area

The DKI Jakarta Province is divided into six administrative districts, Central Jakarta, North Jakarta, West Jakarta, South Jakarta, East Jakarta, and Seribu Islands, as can be seen in Figure 1. Geographically, DKI Jakarta is located at 6°12′ South Latitude and 106°48′ East Longitude. DKI Jakarta generally has a hot climate with a maximum air temperature ranging from 32.7 to 34 °C during the day, and a minimum air temperature ranging from 23.8 to 25.4 °C at night. The average rainfall throughout the year is 237.96 mm with a humidity level reaching 73.0–78.0% and an average wind speed reaching 2.2–2.5 m/s. Geographically, DKI Jakarta is in the lowlands with an average height of 8 m above sea level.

DKI Jakarta is the capital city of the Republic of Indonesia and the center of economy, politics, and culture, located on Java Island. DKI Jakarta has an area of 662.33 km². The population of DKI Jakarta in 2024 was 11.34 million people. Jakarta was originally called Sunda Kelapa until 1619 when the Dutch changed the name to Batavia. Finally, its name was changed to Jakarta during the Japanese occupation and independence on 17 August 1945.

2.2. Hazardous Waste Data Collection

Using a carefully crafted checklist and database authorized by the Ministry of Environment and Forestry (MEF) of the Government of the Republic of Indonesia and the Office of Environment and Forestry of the DKI Jakarta Province, the study’s data collection approaches included focus groups and in-depth interviews with important environmental key resource persons and experts as well as local hazardous-waste-producing sectors in the districts of Jakarta to guide the hazardous waste data entry and verification. Following the completion of data collection, a semi-quantitative analysis was used to estimate risk, employing hazard, vulnerability, and likelihood criteria based on the methodology approved by MEF. The risk assessment carefully examined the possible risks and the degree of exposure. The following data and information are needed for hazardous waste risk assessment, with reference to the Indonesia Ministry of Environment Regulation No. 74 of 2019 on hazardous material and hazardous waste management emergency program: locations of industries denoted as sites, types and activities of industries denoted as sectors, hazardous waste category, hazardous waste classification, hazardous waste generation, source of hazardous waste, potential threats to public health, hazardous waste management capacity, the existence of institutions for hazardous waste emergency response, and provincial hazardous waste emergency program (Ministry of Environment and Forestry of the Republic of Indonesia, 2019) [21]. Following the regulation, the methodologies used to quantify waste in each sector were based on the data recorded by industrial sectors that were verified and ground-checked by the officer from the Office of Environment and Forestry of the DKI Jakarta Province. The data then were entered into the database and updated annually. During the study, the research team was also involved in performing field verification. The regulation was applied for several years until it was amended, and this limits any changes in waste reporting regulations between the two years that could have affected the data.

Based on the provisions of the MEF regulations, hazardous-waste-producing sectors in Indonesia are divided into six sectors as follows: manufacture, agroindustry, energy and oil and gas mining, infrastructure, services, and healthcare (

Table 1. Common hazardous waste sectors according to the regulation of the MEF.

No	Sectors	Sector Details
1	Manufacture	Chemical industries, manufacture
2	Agroindustry	Agroindustry
3	Energy and Oil and Gas Mining	Energy, mining and oil and gas
4	Infrastructure	Infrastructure and construction
5	Services	Hazardous waste treatment and transports
6	Healthcare	Hospitals, community health services, health clinics, laboratories

). The source of data was the recording and reporting system of the MEF for the years 2021 and 2022.

2.3. Hazardous Waste Criteria and Risk Analysis

Data that were relevant to hazardous waste were categorized based on the hazardous waste category, hazardous waste classification, hazardous waste generation, source of hazardous waste, potential threats to public health, hazardous waste management capacity, institutional hazardous waste emergency responses, and provincial hazardous waste emergency program. According to the Government Regulation No. 22 of 2021 on hazardous waste management, category 1 is for hazardous wastes that have an acute (fast or sudden) and direct impact on humans, as well as a negative impact on the environment. Meanwhile, category 2 is for hazardous waste that has a non-acute effect (delay) and has an indirect impact on humans and the environment. This category has toxicity that tends to be sub-chronic or chronic (long-term). The collected data were assessed to determine the risk criteria using the risk potential hazard value as listed in

Table 2. Hazardous waste criteria and hazard potential level values following the Government Regulation No. 22 of 2021 on hazardous waste management.

No	Components	Code	Hazards	Hazards Potential Level
				Value = 1	Value = 2	Value = 3
1	Hazard	A	Hazardous waste generation	<10 tons	10–30 tons	>30 tons
		B	Hazardous waste category	Hazardous waste category 2	Hazardous waste category 1	N/A
2	Vulnerability	C	Number of affected population	<16 million people	16–32 million people	>32 million people
3	Capacity	D	Hazardous waste management capacity	There are >2 areas contaminated by hazardous waste and emergency events	There are 1–2 areas contaminated by hazardous waste and emergency events	There is no areas contaminated by hazardous waste and emergency events
		E	The existence of institutional for hazardous waste emergency response	Not available	Available
		F	The existence of a potential hazardous waste emergency program at provincial scale	Not available	Available

. The determination of hazardous waste criteria and risk was based on the information labeled on the hazardous wastes combined with tests and ground checks performed by the related authority following the regulations.

After the hazardous waste risk criteria were determined and rated, data were calculated using components mentioned in Table 1 and risk formula (R) as follows:

$$R=\left(\sum \mathsf{A}+\sum \mathrm{B}\right)\times \left({\displaystyle \frac{\sum \mathrm{C}}{\sum \mathrm{D}+\sum \mathrm{E}+\sum \mathrm{F}}}\right)$$

2.4. Hazardous Waste Risk Matrix

To calculate the probability of risk, a Likert scale from 1 to 3 was used to assign a score to each of the following: hazardous waste classification, hazardous waste generation, numbers of impacted populations, hazardous waste management capacity, institutional hazardous waste emergency response, and provincial hazardous waste emergency program. High, medium, and low risks are denoted by scores of 1.5–3, 0.8–1.5, and 0–0.7, respectively (Figure 2).

2.5. Hazardous Waste Data Analysis

The scores acquired from the risk level were summed up and divided by the number of samples to obtain the average score of the industrial disaster potential.

2.6. Hazardous Waste Risk Mapping

This mapping used the Geographic Information System (GIS) platform, that is, QGIS version 2.16 to visualize districts in Jakarta based on the risk level of hazardous waste for the years 2021 and 2022. Based on this mapping, the trend, distribution, and identification of districts with the highest risk were analyzed.

2.7. Spatial Statistical Analyses

This study used the global Moran’s I index to study whether the total numbers of the hazardous waste sites, the total hazardous waste amounts, and the average hazardous waste amounts of the five districts in DKI Jakarta Province were spatially correlated in 2021 and 2022, according to the following steps, as described by Rusmili et al. [22]:

First, we determined the spatial distance weight matrix denoted as W between the five districts in DKI Jakarta Province. When i = j, ${\tilde{\omega }}_{ij}$ takes the value of 0; otherwise, ${\tilde{\omega }}_{ij}$ takes the reciprocal of the spatial distance (d_ij) between districts i and j, as shown in Equation (1).

$$W=\left(\begin{array}{ccc}{\tilde{\omega }}_{11}& \dots & {\tilde{\omega }}_{1n}\\ \dots & {\tilde{\omega }}_{ij}& \dots \\ {\tilde{\omega }}_{n1}& \dots & {\tilde{\omega }}_{nn}\end{array}\right);\mathrm{w}\mathrm{h}\mathrm{e}\mathrm{n} i=j, {\tilde{\omega }}_{ij}=0;\mathrm{w}\mathrm{h}\mathrm{e}\mathrm{n} i\ne j, {\tilde{\omega }}_{ij}={\displaystyle \frac{1}{d_{ij}}}$$

(1)

Second, row standardization of the spatial weight matrix was conducted, i.e., each element of the matrix ${\tilde{\omega }}_{ij}$ was divided by the sum of its row elements to obtain a new matrix element ${\omega }_{ij}$. Then, the sum of each row element of such a standardized weight matrix is 1, as shown in Equation (2).

$${\omega }_{ij}={\displaystyle \frac{ {\tilde{\omega }}_{ij}}{{\sum }_{j=1}^n {\tilde{\omega }}_{ij}}}$$

(2)

Third, the Moran’s I index of the total numbers of the hazardous waste sites, the total hazardous waste amounts, and the average of the hazardous waste amounts of the five districts in DKI Jakarta Province was calculated based on Equation (3).

$$I={\displaystyle \frac{n}{{\sum }_{i=1}^n{\sum }_{j=1}^n {\omega }_{ij} }}\times {\displaystyle \frac{{\sum }_{i=1}^n{\sum }_{j=1}^n {\omega }_{ij} \left({PM}_i-\overline{PM}\right)\left({PM}_j-\overline{PM}\right)}{{\sum }_{i=1}^n{\left({PM}_i-\overline{PM}\right)}^2}}$$

(3)

In Equation (3), PM_i is the observed value of the variable of interest in region i, and PM is the mean of all values.

The value of Moran’s I index ranges from negative one to positive one. Values close to negative one indicate that the patterns of the hazardous waste sites, the total hazardous waste amounts, and the average of hazardous waste amount concentrations tend to be randomly dispersed, while values close to positive one indicate that the patterns of the hazardous waste sites, the total hazardous waste amounts, and the average of hazardous waste amounts tend to be clustered.

The next analysis is the LISA, which stands for Local Indicator of Spatial Association. This index indicates the hazardous waste sites, the total hazardous waste amounts, and the average hazardous waste amounts in a district are correlated with the hazardous waste sites, the total hazardous waste amounts, and the average hazardous waste amounts in another district. The equation for calculating LISA is shown in Equation (4).

$$LISA={\displaystyle \frac{\left(x_i-\overline{x}\right)}{\sqrt{S^2}}} \sum _j{\omega }_{ij}\left(x_i-\overline{x}\right)$$

(4)

In Equation (4), x_i is the observed value of the variable of interest in region i, and x is the mean of all values.

The results of LISA were classified into four classes as follows. The high–high class, indicates high-incidence districts were influenced by high-incidence districts, and among those districts, there were strong correlations. High–low and low–high classes indicate high- or low-incidence districts were influenced by high- or low-incidence districts, and among those districts, there were strong-to-weak correlations. Low and low classes indicate low-incidence districts were influenced by low-incidence districts, and among those districts, there were weak correlations [23].

2.8. Comparative Statistical Analyses

Comparative statistical analyses were performed using x². This analysis aimed to test the differences in the total numbers of the hazardous waste sites, the total hazardous waste amounts, and the average of hazardous waste amounts and the statistical differences among five districts in DKI Jakarta Province between the years 2021 and 2022. The significance was tested at the p-value < 0.05.

3. Results

3.1. Trends of Hazardous Waste Distributions by Sites, Total Amounts, and Averages in 2021 and 2022

Figure 3 exhibits the distributions of the hazardous-waste-producing sites with their tonnages in districts of DKI Jakarta Province in 2021 and 2022. The total number of assessed hazardous-waste-producing sites was 2883 sites in 2021 and it increased to 4373 sites in 2022. The hazardous-waste-producing sites were mostly presented in the north and east of Jakarta. In the year 2022, there was a presence of hazardous-waste-producing sites in West and South Jakarta.

Figure 4 exhibits the temporal trends of the numbers of the waste-producing sites in districts of DKI Jakarta Province in 2021 and 2022. The total number of assessed hazardous-waste-producing sites was 2883 sites in 2021 and increased to 4373 sites in 2022. Increases in sites were observed in all districts, including Central Jakarta, East Jakarta, North Jakarta, West Jakarta, and South Jakarta. Sharp increases were observed in East Jakarta and North Jakarta, from 1075 sites in 2021 to 1895 in 2022 for East Jakarta and from 1325 sites in 2021 to 1868 in 2022 for East Jakarta. The statistical test shows that the increase in the number of waste-producing sites in districts of DKI Jakarta Province in 2021 and 2022 is significant, with x² = 50.943 and the p-value < 0.00001 (

Table 3. Comparative statistical parameters.

Variables	Parameters
	x2	p-Value
Comparisons of the numbers of the hazardous waste sites in 2021 and 2022	50.943	0.00001
Comparisons of the total of hazardous waste amounts in 2021 and 2022	64,094.571	0.00001
Comparisons of the averages of hazardous waste amounts in 2021 and 2022	43.758	0.00001

). The hazardous-waste-producing sectors generated more waste that increased from 1177 to 45,000 ton ranges in 2021 to 4440 to 63,374 ton ranges of hazardous waste in 2022, which equals a 17.21% increase (Figure 3). These increases were related to the increases in hazardous-waste-producing sites. Figure 5 exhibits the distributions of the total hazardous waste amounts in districts of DKI Jakarta Province in 2021 and 2022. The patterns for both years show similarities, with the highest hazardous waste amounts observed in North Jakarta, followed by East Jakarta and West Jakarta. The significant differences (x² = 64,094.571 and p-value < 0.00001) (Table 3) were observed in the total hazardous waste amounts that decreased in 2022. The highest hazardous waste amounts were recorded as 525,190 tons in 2021, which reduced to 328,686 tons in 2022, or reduced to 37.41%. Based on Figure 6, East Jakarta was known as the only district that has the highest increase in its hazardous waste from 2021 to 2022, while other districts were observed to experience reductions in hazardous waste emissions.

Figure 7 exhibits the temporal trends of the averages of hazardous waste amounts per site in tons in districts of DKI Jakarta Province in 2021 and 2022. On average and despite an increase in the number of hazardous-waste-producing sites, the amounts of waste released by sites reduced. This significant reduction was observed in all districts except in East Jakarta (x² = 43.758 and p-value < 0.00001) (Table 3). An increase in the number of sites in East Jakarta was followed by the waste amounts released and also the averages of waste by site, from 81.93 tons in 2021 to 90.66 tons in 2022. Sharp reductions were observed in West Jakarta from 125.66 tons in 2021 to only 34.78 tons in 2022.

3.2. Trends of Hazardous Waste Distributions by Sectors in 2021 and 2022

There were variations in hazardous waste distributions by sectors in 2021 and 2022, as can be seen in

Table 4. Hazardous waste distributions by sectors in 2021 and 2022.

Hazardous Waste Sectors	Amounts in Tons		Trends
	2021	2022
Manufacture	238,649.97	224,045.80	Decrease
Agroindustry	51,599.99	57,314.04	Increase
Energy and Oil and Gas Mining	58,049.99	57,314.04	Decrease
Infrastructure	6449.99	5210.36	Decrease
Services	283,799.96	98,996.98	Decrease
Healthcare	6449.99	78,155.51	Increase

. In 2021, the hazardous wastes were mostly generated by manufacture and service, in particular hazardous waste treatment and transportation sectors. Those sectors accounted for approximately more than 50% of hazardous wastes generated in 2021. In 2022, the trends were shifting. Manufacturing is still the highest waste emitter, followed by hazardous waste treatment and transport and healthcare sectors. In comparison to 2021, in 2022, the hazardous wastes produced by hazardous waste treatment and transport sectors were reduced, while at the same time, the healthcare sectors showed sharp increases.

3.3. Trends of Hazardous Waste Distributions by Types and Characteristics in 2021 and 2022

Table 5. Hazardous waste distributions by dominant types and characteristics in each district in 2021 and 2022.

Districts	Types		Characteristics
	2021	2022	2021	2022
Central Jakarta	Medical waste	Medical waste	Infectious	Infectious
North Jakarta	Trichloroethylene, fly ash	Medical waste, fly ash	Explosive	Infectious
West Jakarta	Medical waste, copper slag	Medical waste, fly ash	Corrosive	Infectious
South Jakarta	Medical waste, synthetic oil	Medical waste, synthetic oil	Infectious	Infectious
East Jakarta	Sludge, mill scale	Sludge, mill scale	Toxic	Toxic

presents the hazardous waste distributions by dominant types and characteristics in each district in 2021 and 2022. In 2021, healthcare-related sector wastes were generated in Central and South Jakarta with infectious characteristics. Some industrial-related wastes were observed in North and East Jakarta with dominance of emissions of trichloroethylene and sludges. While this changed in 2022, medical waste was common in all districts in Jakarta, DKI Jakarta. This condition indicates that all districts in Jakarta are threatened by infectious waste.

3.4. Hazards, Vulnerability, and Capacity Trends in Each District in 2021 and 2022

Table 6. Hazards, vulnerability, and capacity scores of each district in 2021 and 2022.

Districts	Hazard		Vulnerability		Capacity
	2021	2022	2021	2022	2021	2022
Central Jakarta	4	4	7	7	4	4
North Jakarta	5	5	7	7	4	4
West Jakarta	4	4	7	7	4	4
South Jakarta	4	4	7	7	4	4
East Jakarta	5	5	7	7	4	4

presents the hazards, vulnerability, and capacity trends in each district in 2021 and 2022. Between the years 2021 and 2022, there were no differences in terms of hazards, vulnerability, and capacity of each district. Comparisons among districts showed that all districts have similar vulnerability and capacity to deal with disasters related to the hazardous wastes. However, each district has differences in terms of hazards. North and East Jakarta have the highest scores in this category since they have higher hazardous waste amounts in comparison to other districts.

3.5. Hazardous Waste Risks of Each District of Jakarta

Table 7. Hazardous waste risks of each district of Jakarta.

Districts	Scores	Remarks
Central Jakarta	7	Medium
North Jakarta	8.75	Medium
West Jakarta	7	Medium
South Jakarta	7	Medium
East Jakarta	8.75	Medium
Average	7.7	Medium

Scores 0–5.0 (low risk), 5.1–10.0 (medium risk), and 10.1–15.0 (high risk).

presents the hazardous waste risks of each district of Jakarta. High risks were observed for North and East Jakarta districts with scores of 8.75. Lower risks were observed for Central, West, and South Jakarta districts. All districts fall into the medium-risk category. At provincial levels, urban Jakarta has a score of 7.7 and is categorized as having medium risk.

3.6. Spatiotemporal Trends and LISA Cluster Maps of Hazardous Waste Distributions by Sites, Total Amounts, and Averages in 2021 and 2022

Spatial statistical analyses of variables of the total number of hazardous waste sites, the total hazardous waste amounts, and the average of hazardous waste amounts were performed using Moran’s I, an index ranging from −1 (indicating a perfect negative spatial autocorrelation and confirming a dispersion or a regular pattern) to +1 (indicating a perfect positive spatial autocorrelation and confirming a clustering), with a value of 0 indicating the absence of spatial autocorrelation and confirming a spatial randomness. Results of Moran’s I analysis, as can be seen in

Table 8. Moran geostatistical parameters.

Year	Variables	Moran Parameters
		I	Exp.	Var.	SD
2021	Hazardous waste sites	0.96	0.250	0.038	0.789
	Total of hazardous wastes	0.87	0.250	0.004	0.987
	Averages of hazardous wastes	0.93	0.250	0.006	1.520
2022	Hazardous waste sites	0.69	0.250	0.041	0.890
	Total of hazardous wastes	0.85	0.250	0.025	0.971
	Averages of hazardous wastes	0.83	0.250	0.017	1.176

, included values greater than 0 for nearly every year from 2021 to 2022 for total number of hazardous waste sites, the total hazardous waste amounts, and the average of hazardous waste amounts. It shows that the site distributions, the total hazardous waste amounts, and the averages of hazardous waste amounts formed a cluster. There are two clusters, as can be seen in Figure 8. The first cluster, indicated by red or hotspots and denoted as HH and HL in maps, is a cluster of districts having high numbers of sites, high totals of hazardous waste amounts, and high averages of hazardous waste amounts. This cluster has emerged mostly in North, East, and West Jakarta. Those districts are correlated, and it means that the increase in the number of sites and the increase in the total amount of hazardous waste and the averages of hazardous waste amounts in one district are influenced by a district nearby. Another spot is a cold spot that emerged in Central and South Jakarta denoted as LH and LL in the maps. These districts formed a cluster characterized by low numbers of sites and an increase in the total amount of hazardous waste and the average amount of hazardous waste, while a comparison between years shows a decrease in Moran’s I values. This indicates that the hazardous waste sites were not clustered anymore and tended to be dispersed.

4. Discussion

4.1. Trends of Hazardous Waste Distributions by Site Locations in 2021 and 2022

The GIS-based mapping showed that the hazardous-waste-producing sectors tend to be clustered, as can be seen in North and East Jakarta. The cluster of industrial areas is in agreement with industrial sectors in other locations. In Taiwan, it was reported that the distribution of industrial plants as a source of hazardous waste in Changhua County is also clustered in some areas [24]. Similar clusters of industrial plants were also reported in Slovakia. Clustering of industrial plants is considered as a part of urban development [25]. In Indonesia, the cluster approach has been implemented for the embroidery and apparel industrial cluster development program, as can be seen in Padurenan Village, Kudus District [26].

The clustering of industry in Jakarta is related to the topography, landscape, and land use plan of this city. The topography of North and East Jakarta is flatter than other parts of Jakarta. Flatter topography offers more access, especially for hazardous waste sectors, and this explains the presence of clusters. North and South Jakarta are located on the border with the sea and other cities. The sea with its ports is a gateway for export and import activities involving materials that are either produced or required by industrial plants, and this activity will lead to large numbers of the hazardous-waste-producing sectors in the north and east of Jakarta. In comparison, Central Jakarta is a dedicated center of government, which limits the presence of industrial sectors. Similarly to this, the south of Jakarta is mostly dedicated to the housing, office, and healthcare centers for the community that lives in the south. This situation is also limited by the presence of industrial sectors. The emergence of several hazardous-waste-producing sectors in 2022 may be related to the expansion of new industrial areas due to the limited land available.

4.2. Trends of Hazardous Waste Distributions by Sectors in 2021 and 2022

Based on the analyses, the hazardous-waste-producing sectors in urban Jakarta are characterized by the presence of hazardous waste treatment and transport sectors and the emergence of healthcare sectors. This condition is related to the phenomenon that happened between 2021 and 2022, that is, the COVID-19 pandemic. This pandemic that started in 2020 left large amounts of waste, requiring immediate waste treatment. At the same time, the COVID-19 pandemic also caused an increase in healthcare services. This explains the significant amounts of waste released from healthcare sectors. Another situation observed is the slight decrease in hazardous wastes released from manufacturing sectors. This condition is related to the pandemic’s impact on economic activities, including the manufacturing sectors. It has been reported that the pandemic caused manufacturing output to fall at an annual rate of 43% and hours worked to fall at a rate of 38% in the second quarter of 2020 [27]. Similarly to the manufacturing sectors, the decrease in the transportation sectors is also related to the mobility restrictions due to the COVID-19 pandemic. At the time, the Indonesian government released the work-from-home policy. As a result, the transportation activities were reduced, and this explains the decreasing trends in the amount of hazardous waste produced.

4.3. Trends of Hazardous Waste Distributions by Types and Characteristics in 2021 and 2022

In 2021, the types of hazardous wastes were dominated by industrial wastes, including trichloroethylene, copper slag, and mill scale. Trichloroethylene is released into the environment from industrial degreasing operations and water treatment facilities and is found in landfill leachate [28]. Copper slag is a common waste released from industry and the manufacture of cement and concrete [29]. In 2022, the hazardous wastes were shifted and replaced by medical wastes. It is assumed that the pandemic contributed to the increasing types of this waste. The COVID-19 pandemic caused a surge in essential medical supplies usage, leading to a notable increase in medical waste generation [30]. In an urban setting, the medical wastes increased from 79,027 kg/month to 116,714 kg/month due to the COVID-19 pandemic [31]. In Wuhan City, hazardous medical waste peaked at 240 tons per day [32]. This related situation explains the shifting of hazardous wastes from industrial wastes to medical wastes, as can be observed in urban Jakarta from 2021 to 2022. An increase in post-pandemic surges of medical waste was also observed in other locations, as can be seen in

Table 9. Trends of COVID-19 medical waste volume for some selected countries [34].

Countries	Generated Daily Medical Hazardous Waste (Amounts in Tons/Day)
United States of America	8055.03
Brazil	2774.35
India	2160.34
Colombia	550.63
South Africa	469.12
Argentina	454.41
Bangladesh	359.83
Mexico	358.75
Egypt	128.54
Iran	81.31
Italy	45.09
Jakarta, Indonesia (this study)	2170.43

. This is corroborated by the trends and emergence of medical waste in Jakarta following the pandemic in which Jakarta is ranked number 3 globally [33].

4.4. Responses to Hazardous Waste Risks

Hazardous waste risks in Jakarta that have reached a medium level indicate a need to take action. This can be started by immediately implementing practical examples of hazardous waste treatment [35,36], particularly detailing processes such as dark fermentation (DF) for the production of volatile fatty acids (VFAs) from asbestos-containing waste (ACW) and construction and demolition waste (CDW). These VFAs are then utilized in further biogas production processes to create a circular economy. The risks are actually a proxy indicator of poor capacity to deal with any accidents caused by hazardous wastes regarding the explosive characteristics. The spatiotemporal analyses confirm a cluster of hazardous waste in North and East Jakarta that may be related to the presence of ports facilitating the transport of hazardous wastes. Thus, it is recommended to strengthen the capacity of contaminant and pollutant management systems to monitor the potentials of hazardous wastes released that contaminate the coastal areas [37].

4.5. Trends of Hazardous Waste Regulations

Indonesia has issued several regulations related to hazardous waste management at the national and provincial levels. At the national level, they include Indonesian Law No. 32 of 2009 on the protection and management of the environment, Minister Regulation No. 6 of 2021 on procedures for hazardous waste management, Government Regulation No. 101 of 2014 on hazardous waste management, and the latest Government Regulation No. 22 of 2021 on hazardous waste management. The Indonesian regulations are already in line with the United States EPA regulations on hazardous waste management. While emerging gaps lie in autonomy issues, provinces in Indonesia following the law on autonomy has led the provincial government to exercise their own right to manage and determine the course of developments, and sometimes, this is not in line with the national objectives. The provincial government is aiming to raise revenue and incomes, through plans including the opening of new industrial areas and improving productivity, while the national regulations are mostly concerned with limiting the expansion of industrial areas. This has become a major hurdle in controlling the expansion of industrial areas along with their hazardous wastes at provincial levels.

The significant finding of this study is the massive increase in medical waste. This rise in medical waste is related to the recent pandemic, COVID-19. This change has been responded to by releases and issues of regulations specifically addressing the medical wastes. The new regulation is the Indonesian Ministry of Health Regulation No. 18 of 2020 on procedures for medical waste management. Despite the regulation being available, the challenges have been observed. The high volume of medical waste produced has exceeded the capacity of waste processing. At the same time, is it very difficult to limit the production of this medical waste [38]. This overwhelming medical waste is also reported in other locations. The implementation of the regulation is also challenged by insufficient skilled human resources to handle the wastes, very limited storage capacity, and the absence of proper safe medical waste disposal sites [39]. To cope with this situation, the Indonesian government has responded through several training sessions on handling medical waste.

4.6. Spatiotemporal Trends of Hazardous Waste Distributions by Sites, Total Amounts, and Averages

The spatial statistical analyses confirm a spatiotemporal trend of hazardous waste distributions by sites, total amounts, and averages. It shifted from a cluster in North, East, and West Jakarta in 2021 to be more dispersed in 2022. As a result of the pandemic, there were numerous sectors that collapsed and postponed their operations in industrial areas in North and East Jakarta, while at the same time, there was a growing number of health clinics providing services for COVID-19 swab tests that emerged and spread across South and Central Jakarta. This explains that the hazardous waste sites were not clustered anymore since they emerged randomly in districts other than North and East Jakarta as a result of growing healthcare sectors.

The presence of clusters with high Moran’s I value shows a correlation between districts. It means that an increase in hazardous waste in a district is correlated with an increase in other districts. In this regard, industrial sectors are related to the other sectors. Growing infrastructure and mining and oil and gas sectors require a production of machinery to support the operation of these sectors. As a result, there will be a growth of manufacturing industries to produce machinery in neighboring districts. A manufacturing activity then will also produce waste, and this explains the correlation of waste emission between one district and another district.

4.7. Limitations of the Study

The measurements of hazardous waste trends in the current study are limited to the perspective of the growth of industrial sites solely. Meanwhile, the growth of industrial sites in particular that has a potential impact on the rise in hazardous waste risk amounts is related to the external and internal factors. The external factors related to the growth of the regional economy in this case are Southeast Asian regions that have a role in boosting investments in Indonesia and in Jakarta. These investments will bring more capital, and the industrial sector will grow. The internal factors can be more complicated. It ranges from the population to economical growth that boosts the demand of certain products that increase the generation of hazardous wastes [40]. These limits then should be considered in future studies. The hazardous waste trends investigated in this study are based on the authorized database that is limited to the formal sectors. Thus, the possible biases caused by recent informal industrial activities have limited this study and require further elaboration. This study confirms important findings related to the increasing trends in medical hazardous waste. Thus, in the future, it is recommended to elaborate on the particular potential environmental and public health implications of the widespread distribution of infectious medical waste across all districts in Jakarta.

5. Conclusions

The trends of hazardous wastes in urban Jakarta and its districts showed increasing and decreasing directions for the years 2021 and 2022. The results confirmed that, from 2021 to 2022, there were increases in hazardous-waste-producing sectors and decreases in the amount of hazardous waste produced. From 2021 to 2022, the hazardous-waste-producing sectors increased by 55.96%, and the total hazardous waste amount across Jakarta decreased from 644,999.93 tons in 2021 to 521,036.75 tons in 2022. The hazardous-waste-producing sectors were mostly in North and East Jakarta, and there were trends of new hazardous-waste-producing sectors emerging in West and South Jakarta districts from 2021 to 2022. The hazardous-waste-producing sectors were dominated by manufacture sectors and emerging healthcare sectors. From 2021 to 2022, the hazardous waste trends shifted from industrial to medicinal wastes, and the risks shifted from corrosive, explosive, and toxic to infectious risks. To conclude, the risk levels of urban Jakarta based on hazardous waste risk scores fall into the medium levels. The trends are assumed to be related and impacted by the pandemic. This is considering that the years 2021 and 2022 are when COVID-19 were prominent.

In 2021, high numbers of hazardous waste sites, high totals of hazardous waste amounts, and high averages of hazardous waste amounts have created a hotspot or a cluster of highly hazardous waste sites in Jakarta, located mainly in North and East Jakarta, while a contrasting coldspot was observed in Central and South Jakarta. In 2022, these hotspot and cluster patterns then tended to change into dispersed patterns. Based on spatial statistical analyses, these significant changes in cluster patterns are indicated by a reduction in Moran I values from 0.87–0.96 in 2021 to 0.69–0.85 in 2022. This indicates that the hazardous waste sites have moved from North and East Jakarta District to other districts.