Search

Graphical abstract The seasonal burning of crop residue significantly affects the environment, leading to poor air quality over Indo-Gangetic Plain (IGP) in India. Hence, there have been significant efforts to minimize crop residue burning through policy, innovations, and awareness measures. However, an abrupt increase in paddy residue burning was observed over IGP during 2020. Hence, the study explores the factors leading to this sharp rise. The business as usual trends analysis revealed that paddy crop residue burning activities increased significantly (60%) in 2020 compared to the previous year. The massive increase in crop residue burning consequently seems to be linked with the COVID-19 pandemic, which affected the farmer’s income, including the poor compliance by the regulatory authorities. The study also highlights the issues and prospects for sustainable crop residue management and explores the solutions to minimize crop residue burning. There are few crops in India that have guaranteed minimum sale price and are also subsidized. These provisions encourage farmers to grow those particular crops, resulting in the generation of large amounts of crop residue from these specific crops. There have been several efforts by the Indian government, including based on recent court intervention. Still, there is no respite from burning activities and the occurrence of Delhi winter smog every year. Hence, the study emphasizes a need to adopt integrated approaches having in situ eco-friendly solutions, which enhances the farmer’s income and focuses on employability, capacity building, awareness generation, and in situ economically viable solutions.

In India, Indo-Gangetic Plains (IGP) is becoming the hotspot of air pollution due to increasing anthropogenic activities such as rapid industrial growth, infrastructure development, transportation activities, and seasonal practice of crop residue burning. In the current study, seasonal variation in ambient air quality for 14 parameters, i.e., particulate matter (PM), trace gases, and volatile organic compounds (VOCs), along with meteorological parameters, was studied in 21 districts of the Haryana state for year 2019, situated in IGP. To analyze spatial variation of pollutants, ambient air quality data of 23 continuous ambient air quality monitoring stations were divided into three zones based on ecology and cropping pattern. All the zones showed annual mean PM10 and PM2.5 concentrations much higher than national ambient air quality standards. Annual mean PM10 concentration (±standard deviation) in Zones-1, 2, and 3 was 156±86, 174±93, and 143±74 μg m−3, whereas for PM2.5 was 71±44, 85±54, and 78±47 μg m−3. The results showed a considerable seasonal variation in the concentration of all pollutants. Most of the pollutants peak in the post-monsoon season, followed by winters in which crop residue burning predominates in many parts of the Haryana. PM10 concentrations increased by 65–112% and PM2.5 concentrations increased by 131–147% in the post-monsoon season compared to monsoons. The post-monsoon season showed the highest concentration of PM10, NO, and toluene (Zone-1); and PM2.5, NH3, CO, and benzene (Zone-2); whereas in winters, SO2 (Zone-1); ethylbenzene, m,p-xylene, and xylene (Zone-2); and NO2 and NOx (Zone-3) showed the maximum pollution levels. The O3 concentration was highest in the pre-monsoon season (Zone-1). The satellite-based fire counts and PCA results show a significant influence of crop residue burning in the post-monsoon season and solid biomass burning in winters on Haryana’s air quality. The study could help to understand seasonal variation in ambient air quality and the influence of factors such as crop residue burning in the IGP region, which could help to formulate season-specific control measures to improve regional air quality.

We have estimated the spatial changes in NO2 levels over different regions of India during the COVID-19 lockdown (25 March–3 May 2020) using the satellite-based tropospheric column NO2 observed by the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring Instrument (TROPOMI), as well as surface NO2 concentrations obtained from the Central Pollution Control Board (CPCB) monitoring network. A substantial reduction in NO2 levels was observed across India during the lockdown compared to the same period during previous business-as-usual years, except for some regions that were influenced by anomalous fires in 2020. The reduction (negative change) over the urban agglomerations was substantial (∼ 20 %–40 %) and directly proportional to the urban size and population density. Rural regions across India also experienced lower NO2 values by ∼ 15 %–25 %. Localised enhancements in NO2 associated with isolated emission increase scattered across India were also detected. Observed percentage changes in satellite and surface observations were consistent across most regions and cities, but the surface observations were subject to larger variability depending on their proximity to the local emission sources. Observations also indicate NO2 enhancements of up to ∼ 25 % during the lockdown associated with fire emissions over the north-east of India and some parts of the central regions. In addition, the cities located near the large fire emission sources show much smaller NO2 reduction than other urban areas as the decrease at the surface was masked by enhancement in NO2 due to the transport of the fire emissions.

Near real-time monitoring of major air pollutants, i.e., particulate matter (PM

Air pollution has emerged as a leading global health risk in recent decades, where its health impacts are primarily focused on urban areas. In India, semi-urban and rural areas are also emerging as air pollution hotspots. As these regions are out of focus, the current study monitored air pollution (PM

The emissions from agricultural activities significantly impact the air quality at local (rural) and regional scales. The study monitored the near real-time concentrations of emission from agrarian activities, i.e., particulate matter (PM10, PM2.5, PM1), traces gases and VOCs, along with meteorological parameters in a rural area of Indo-Gangetic Plains (IGP). As different agricultural activities take place simultaneously in the region, sampling period was divided into three phases based on regional agricultural activities as HB (harvesting-burning) period, BTS (burning-tillage-sowing) period and PFS (pesticide-fertilizer spray) period. The highest mean concentration (± standard deviation) of particulate matter, i.e., PM10, PM2.5, PM1 was observed during HB period as 151.0 ± 52.3, 94.7 ± 32.9 and 41.0 ± 16.3 μgm-3 followed by PFS as 121.7 ± 49.1, 87.8 ± 35.5 and 39.7 ± 15.7 μgm-3 and BTS period as 92.5 ± 38.8, 63.5 ± 28.4, 26.6 ± 10.9 μgm-3 respectively. The mean concentration of NO (8.4 ± 3.4 ppb), SO2 (5.8 ± 1.2 ppb), CO (0.9 ± 0.3 ppm), O3 (12.5 ± 3.3 ppb) was also highest during harvesting-burning period. In the burning-tillage-sowing period, the mean concentration of NO2 (31.0 ± 2.9 ppb), benzene (2.8 ± 0.6 μgm-3) and o-xylene (2.1 ± 0.3 μgm-3) were highest. The data of crop residue burning fires showed that during HB period, around 34,683 active fires were there in the region (state of Punjab), whereas, in studied district, the number of fire counts were 635. During the HB period, around 70% of the air masses were originated within a 500 km area, whereas during the BTS and PFS period, 75% and 86% of air masses were originated from 500 km region, respectively. The ratio of PM2.5/PM10 during study period ranged from 0.63 to 0.72 and was observed highest during PFS period. The current study investigated the influence of agricultural activities on air quality during post-monsoon season in a rural area of Indo-Gangetic Plains to understand the impact of these activities on air quality in the region and plan mitigation strategies.

Population growth will lead to an increase in food demand, which will exert pressure on crop production and likely increase the agricultural crop residue. The present study estimates atmospheric emissions of various pollutants from crop residue burning using the Intergovernmental Panel on Climate Change guidelines. In India 488 Mt of total crop residue was generated during 2017, and about 24% of it was burnt in agricultural fields. This resulted in emissions of 824 Gg of Particulate Matter (PM2.5), 58 Gg of Elemental Carbon (EC) and 239 Gg of Organic Carbon (OC). Additionally, 211 Tg of CO2 equivalent greenhouse gases (CO2, CH4, N2O) were also added to the atmosphere. However, crop residue can also be used for energy production in biomass power plants and has the potential of 120 TWh of electricity generation. This accounts for 10% of the total energy production of India. Trend analysis in a Business As Usual (BAU) model shows that crop residue burning emissions will increase by 45% in 2050 having 2017 as the base year. The study also examines the various sustainable approaches and proposes an integrated crop residue management model to minimize the adverse impact of agricultural waste burning on human health and the environment.

We have estimated the spatial changes in NO2 levels over different regions of India during the COVID-19 lockdown (25th March–3rd May 2020) using the satellite-based tropospheric column NO2 observed by the Ozone Monitoring Instrument (OMI) and the Tropospheric Monitoring Instrument (TROPOMI), as well as surface NO2 concentrations obtained from the Central Pollution Control Board (CPCB) monitoring network. A substantial reduction in NO2 levels was observed across India during the lockdown compared to the same period during previous business-as-usual years, except for some regions that were influenced by anomalous fires in 2020. The reduction (negative change) over the urban agglomerations was substantial (∼ 20–40 %) and directly proportional to the urban size and population density. Rural regions across India also experienced lower NO2 values by ∼ 15–25 %. Localised enhancement of NO2 associated with isolated emission increase scattered across India, were also detected. Observed percentage changes in satellite and surface observations were consistent across most regions and cities, but the surface observations were subject to larger variability depending on their proximity to the local emission sources. Observations also indicate NO2 enhancements of up to ∼ 25 % during the lockdown associated with fire emissions over the north-east, and some parts of central regions. In addition, the cities located near the large fire emission sources show much smaller NO2 reduction than other urban areas as the decrease at the surface was masked by enhancement in NO2 due to the transport of the fire emissions.

The World Health Organization has declared the COVID-19 pandemic a global public health emergency. Many countries of the world, including India, closed their borders and imposed a nationwide lockdown. In India, the lockdown was declared on March 24 for 21 days (March 25–April 14, 2020) and was later extended until May 3, 2020. During the lockdown, all major anthropogenic activities, which contribute to atmospheric pollution (such as industries, vehicles, and businesses), were restricted. The current study examines the impact of the lockdown on tropospheric NO2 concentrations. Satellite-based ozone monitoring instrument sensor data were analyzed in order to investigate the variations in tropospheric NO2 concentrations. The results showed that from March 1 to 21, 2020, the average tropospheric NO2 concentration was 214.4 ×1013 molecule cm-2 over India, and it subsequently decreased by 12.1% over the next four weeks. An increase of 0.8% in tropospheric NO2 concentrations was observed for the same period in 2019 and hence, the reduced tropospheric NO2 concentrations can be attributed to restricted anthropogenic activities during the lockdown. In the absence of significant activities, the contribution of various sources was estimated, and the emissions from biomass burning were identified as a major source of tropospheric NO2 during the lockdown. The findings of this study provide an opportunity to understand the mechanism of tropospheric NO2 emissions over India, in order to improve air quality modeling and management strategies., Atmospheric Science; Air Quality; Environmental Analysis; Environmental Assessment; Environmental Pollution; COVID-19 lockdown; NO2; National Clean Air Programme; Biomass Burning; OMI

Air pollution affects not only the air quality in megacities but also in medium and small-sized cities due to rapid urbanization, industrialization, and other anthropogenic activities. From October 28, 2015 to November 3, 2015, the Indo-Gangetic Plains region, including Chandigarh encountered an episode of poor visibility during the daytime. The daily average PM

Emissions from the crop residue burning adversely affect the regional and global air quality including public health risks. In this study, a district-wise comprehensive emission inventory of key pollutants (PM2.5, PM10, CO, CO2, SO2, NOx, N2O, NH3, CH4, NMVOC, EC, OC, PAH) emitted during primary crop residue burning was developed using activity data for the major agrarian states of north India for the agricultural year 2017–18. The emissions were scaled to the spatial resolution of 1 km grid to study the spatial distribution of crop residue burning activities using VIIRS Thermal anomalies datasets. An estimated 20.3 Mt and 9.6 Mt of crop residue were burned in Punjab and Haryana, resulting in an emission of 137.2 Gg and 56.9 Gg of PM2.5 and 163.7 Gg and 72.1 of PM10 Gg for respective states. The emissions of EC, OC, and PAHs were 8.6 Gg, 45.7 Gg, and 0.08 Gg in Punjab, whereas in Haryana emissions were 3.7 Gg, 17.7 Gg, and 0.03 Gg, respectively. The results show that rice and wheat crops were major contributor to residue burnt at the field (>90%) leading to the high load of atmospheric emissions in the IGP region. Further, CO2 equivalent greenhouse gas emissions were 34.8 Tg and 17.3 Tg for Punjab and Haryana, respectively. Around 30000 and 8500 active fires were detected by VIIRS over the agricultural area of Punjab and Haryana during the studied year. The GIS-based bottom-up approach using gridded emission inventory shows pollutant distribution dominates over the south-western part of Punjab and north-western region of Haryana. The proximity of these regions to Delhi and transboundary movement of emissions towards Indo-Gangetic plains causes high air pollution episodes. The high-resolution inventory of various pollutants will be useful for regional air quality models to better predict and manage the hotspot of air pollution.

The long-term trend of air pollutants was studied in Chandigarh, located in Indo-Gangetic Plains of India. The SPM, PM10, NOx, and SO2 depict site-specific variation having different anthropogenic activities. The results indicate that PM10 levels in Chandigarh remain higher than the prescribed annual ambient air quality standards (60 μg m−3) of India. Seasonal Kendall test indicates a declining trend of PM10 for the year 2003 to 2018 at an industrial and commercial site (1996–2016). There is a significant increase in NOx levels at all locations except at commercial sites. The results of the linear regression model and Theil–Sen slope show that SPM is declining at all locations, but results are not statistically significant. Interestingly, PM10 levels at the industrial site display a significant declining trend (1.3% year−1). Similarly, NOx levels are increasing at all sites but having a statistically significant trend at a rural location (8.9% year−1) and residential site (15.2% year−1). Air pollutants show strong seasonal variability having a higher concentration in post-monsoon and winter season, which found to be linked with regional anthropogenic activities such as crop residue burning and use of solid biomass fuel for cooking and other purposes. Lowest PM10 levels were observed during the monsoon and having a decline of 47.4–66.4% as compared to winter levels. Site-specific variations in air pollutants were found to be associated with air quality improvement policies such as shifting of an interstate bus terminal, ban on diesel autos, including strict implementation of air quality norms on industries. As the relative contribution of various pollution sources is still unknown, the seasonal pattern of pollutants will help in knowing the background concentration of pollutants and could help to formulate evidence-based policies to mitigate air pollution under National Clean Air Programme (NCAP).

Air pollution affects not only the air quality in megacities but also in medium and small-sized cities due to rapid urbanization, industrialization, and other anthropogenic activities. From October 28, 2015 to November 3, 2015, the Indo-Gangetic Plains region, including Chandigarh encountered an episode of poor visibility during the daytime. The daily average PM2.5 concentration reached 191 μg/m3, and visibility reduced by ∼2.2 times in the Chandigarh region. PM2.5 concentration was found around 4 times higher than a non-haze day and more than 3 times higher than National Ambient Air Quality Standards for 24 h. A significant correlation between PM2.5 and CO (r: 0.87) during the haze period indicated similarity in their emission sources; which was attributed to the burning of solid organic matter. Further, satellite data and back-trajectory analysis of air masses showed large-scale rice stubble burning in the agricultural fields, adjoining to the city areas. The transboundary movement of air masses below 500 m and meteorological conditions played a major role in building the pollution load in the Chandigarh region. Moreover, the enhanced concentration of biomass burning tracers, i.e., organic carbon (∼3.8 times) and K+ ions (2∼ times) in PM2.5 and acetonitrile (∼2.3 times) in ambient air was observed during the haze event. The study demonstrates how regional emissions and meteorological conditions can affect the air quality in a city; which can be useful for proper planning and mitigation policies to minimize high air pollution episodes.

Air pollutants emissions due to the burning of crop residues could adversely affect human health, environment, and climate. Hence, a multicity campaign was conducted during crop residue burning period in Indo Gangetic Plains (IGP) to study the impact on ambient air quality. Seventeen air pollutants along with five meteorological parameters, were measured using state of the art continuous air quality monitors. The average concentration of PM10, PM2.5, and PM1 during the whole campaign were 196.7±30.6, 148.2±20, and 51.2±8.9 μgm-3 and daily average concentration were found several times higher than national ambient air quality standards for 24h. Amritsar had the highest average concentration of PM2.5 (178.4±83.8 μgm-3) followed by Rohtak and Sonipat (158.4±79.8, 156.5±105.3μgm-3), whereas Chandigarh recorded the lowest concentration (112.3±6.9μgm-3). The concentration of gaseous pollutants NO, NO2, NOx, and SO2 were also observed highest at Amritsar location, i.e., 6.6±2.6ppb, 6.2±0.7ppb, 12.7±3.0ppb, and 7.5±3.3ppb respectively. The highest average O3 and CO were 22.5±19.3ppb and 1.5±1.2ppm during the campaign. The level of gaseous pollutants and Volatile organic compounds (VOCs) found to be elevated during the campaign, which can play an important role in the formation of secondary air pollutants. The correlation of meteorology and air pollutants was also studied, and O3 shows a significant relation with temperature and UV (R=0.87 and 0.74) whereas VOCs shows a significant correlation with temperature (R=-0.21 to -0.47). Air quality data was also analyzed to identify sources of emissions using principal component analysis, and it identifies biomass burning and vehicular activities as major sources of air pollution.

Columnar Aerosol Optical Depths (AOD) over an urban area (Chandigarh) and a rural area (Khera, Fatehgarh Sahib district) situated in the Indo-Gangetic Plains (IGP) of India were analysed to study their temporal heterogeneity in terms of interannual, seasonal and monthly variations. Over the last few decades, IGP has become one of the global hotspots of air pollution due to the increased anthropogenic activities such as traffic, industries, agricultural waste burning etc. Level-2 AODs (550 nm) were retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard NASA's Terra and Aqua satellites, for a period of 14 years (2005–2018). The climatological mean Terra-MODIS (Aqua-MODIS) AOD over the urban location was ~0.497 ± 0.238 (0.474 ± 0.228), whereas over the rural location it was 0.542 ± 0.269 (0.534 ± 0.282). Linear trend analysis estimated an increase in annual mean Terra-MODIS (Aqua-MODIS) AOD at a rate of ~0.009 (0.013) per year over the urban site; whereas over the rural location the rate of increase was ~0.003 (0.004) per year. Results show that the observed increase is ~1.49% (2.41%) of climatological mean AOD over the urban location for Terra-MODIS (Aqua-MODIS), whereas, over the rural location, it was ~0.50% (0.67%). Using the HYSPLIT trajectory model, it was concluded that, during post-monsoon, the observed high AODs can be related to massive crop residue burning in the IGP region. These AOD trends can also be used to track the regional anthropogenic air-pollution changes. An empirical relation between AOD and PM10 was established, which can be used to estimate PM10 over the urban and rural areas of IGP (using MODIS AODs), complementing the sparse ground-based monitoring. Further, satellite-based air pollution data can be used for baseline assessment and understanding the impact of control policies such as National Clean Air Programme and to support formulate evidence-based pollution control strategies.

The major objective of the current study is to estimate the groundwater quality and identify the likely sources of contamination in Chandigarh, India. Total 80 groundwater samples were collected from different locations and at various depths in the study area. Further, physcio-chemical analysis was done to estimate pH, electrical conductivity (EC), total dissolved solids, total hardness (TH), total alkalinity (TA), Na+, K+, Cl−, SO42−, PO43− and NO3−. The groundwater samples collected from shallow water sources were observed to contain higher amount of dissolved salts. EC, TA, Cl−, TH, Na+, and K+ were found relatively higher in the shallow aquifer (

Noise pollution in hospitals is recognized as a serious health hazard. Considering this, the current study aimed to map the noise pollution levels and to explore the self reported non-auditory effects of noise in a tertiary medical institute. The study was conducted in an 1800-bedded tertiary hospital where 27 sites (outdoor, indoor, road side and residential areas) were monitored for exposure to noise using Sound Level Meter for 24h. A detailed noise survey was also conducted around the sampling sites using a structured questionnaire to understand the opinion of the public regarding the impact of noise on their daily lives. The equivalent sound pressure level (Leq) was found higher than the permissible limits at all the sites both during daytime and night. The maximum equivalent sound pressure level (Lmax) during the day was observed higher (>80dB) at the emergency and around the main entrance of the hospital campus. Almost all the respondents (97%) regarded traffic as the major source of noise. About three-fourths (74%) reported irritation with loud noise whereas 40% of respondents reported headache due to noise. Less than one-third of respondents (29%) reported loss of sleep due to noise and 8% reported hypertension, which could be related to the disturbance caused due to noise. Noise levels in and around the hospital was well above the permissible standards. The recent Global Burden of Disease highlights the increasing risk of non communicable diseases. The non-auditory effects studied in the current work add to the risk factors associated with non communicable diseases. Hence, there is need to address the issue of noise pollution and associated health risks specially for vulnerable population.