The Delhi metropolitan area experiences severe air pollution every year in late October or early November. Corresponding to this period, post-harvest rice stubble burning is widely practiced in the surrounding states of Punjab (India) and Haryana, and in some parts of Uttar Pradesh and Himachal Pradesh. The Research Institute for Humanity and Nature’s (RIHN’s) Aakash Project, a cooperative project between Japan and India, has been tackling the issue of air pollution from large-scale rice stubble burning in the Indian Punjab region. The project was launched as an RIHN full research project in April 2020 and will continue until March 2025. This project scientifically examines the connection between stubble burning in the Punjab and severe air pollution in Delhi. Based on this scientific understanding, we will pursue a pathway of social transformation toward clean air, public health and sustainable agriculture. We are approaching stakeholders/involved parties to raise awareness regarding farmer/community behavior that is relevant to stubble burning and air pollution. So far, under the project, we have successfully conducted campaign-based measurements using about 30 small air-pollution measurement devices in the field in 2022 and clarified the linkage between stubble burning in the Punjab and severe air pollution in Delhi. To clarify the goals of our activities, this paper focuses on the underlying issues at stake, describes the current research and findings, and discusses possible mitigation measures. At the end of the project, we aim to make recommendations for creating a sustainable agricultural system that reduces rice-stubble burning.

Air pollution now causes several million deaths each year. Among air pollutants, polycyclic aromatic hydrocarbons (PAHs) and their derivatives, such as nitro-, hydroxy- and quinoid PAHs attract much attention. These pollutants are emitted through burning processes of fossil fuels and vegetation, and exist in gas and particle phases in the air. Despite their strong adverse health effects, including lung cancer, asthma and endocrine disruption, their outdoor and indoor air pollution levels have not been reduced quickly worldwide. Recently, biomass has become popular as a renewable energy source that does not increase the atmospheric concentration of global carbon dioxide, a greenhouse gas implicated in global warming. On the other hand, there are still many areas in developing countries where slash-and-burn farming is practiced, and forest fires have been increasing rapidly worldwide. Therefore, sufficient attention is needed to the health effects of PAHs and related compounds generated from these sources. The aim of this report is to describe the emission and distribution of PAHs and their derivatives in outdoor and indoor air and their health effects, focusing on vegetation fires.

Particulate matter (PM) is an aggregate of particles and chemical/biological components. Some of these components include harmful substances, and fine PM easily reaches the bronchioli and alveoli when inhaled, causing health challenges in the respiratory and immune systems. Exacerbation of respiratory diseases, such as bronchitis and bronchial asthma, is one of the representative cases. There is also concern that PM exacerbates coronavirus disease 2019 (COVID-19). Here, we introduce the health effects of PM and its components and the underlying mechanisms, focusing on the respiratory and immune systems from the perspective of an experimental approach.

Oxidative stress due to exposure to PM_2.5 that generates reactive oxygen species (ROS) is one of the pathways leading to morphologic changes and lung function decrements that are linked to exacerbation of asthma and chronic obstructive pulmonary disease. Biomass burning (BB) is one of the largest sources of PM with its expected induction of ROS through exposure. Open burning of agricultural residues is widely conducted in September and October in Japan, but it is unclear to what extent the oxidative stress induction ability (OSIA) is increased during the active BB season compared to other seasons, when the effects of BB are different. In this study we conducted heme oxygenase-1 assays on PM_2.5 samples collected during the active BB season (October 2015) in Tsukuba, Japan, to clarify the influence of BB on OSIA. On average, BB particles were estimated to be responsible for 25% of PM_2.5, and 80% of OSIA in October 2015. At that time, PM_2.5, BB particles and OSIA were up to two times, eight times and seven times higher, respectively, than during seasons of low BB activity. Thus, elevated concentrations and OSIA are considered to arise mainly from BB particles. The results indicate that management of BB activity is important for good air quality and public health.

Anthropogenic activities such as forest degradation; the expansion of commodity crops, including oil palm; and drainage of fire-prone peatlands have resulted in extensive peatland and forest fires in Indonesia. Uncontrollable and intense peatland fires have frequently occurred in the Indonesian islands of Sumatra and Kalimantan, particularly during the hot and dry seasons of the El Niño-Southern Oscillation. Air pollution in the form of transboundary haze is an urgent issue in Southeast Asia. The physical and chemical properties of the aerosols from peatland fires are fundamental to know when assessing their impact on human health and the environment, conducting source apportionment of haze events, and unraveling their dynamic state in the environment (e.g., secondary aerosol formation). In this paper, we conduct a holistic review of source profiles, key indicators of Indonesian peatland fires at source and receptor sites, and transformation of haze during its long-range transport (aging, secondary aerosol formation) as well as source apportionment in Southeast Asia, using a comprehensive chemical component dataset. Knowledge of the chemical characteristics of particulate matter at Indonesian peatland fire sources and receptor sites is still limited, especially regarding controlling factors (e.g., combustion conditions, peat composition and the effects of vegetative burning on peatland) that determine the Indonesian peatland fire source profile of particulate matter. Additionally, the process of secondary organic aerosol formation derived from Indonesian peatland fires during transport to receptor sites remains largely unresolved.

Biomass burning is the main source of air pollution in many countries and has been strongly linked to many morbid and mortal health outcomes. This scoping review aims to explore the current and emerging approaches linking health and air pollution from biomass burning. A literature search through PubMed was conducted to identify studies linking health and air pollution from biomass burning through the use of air quality data collection methods. A total of 197 studies were initially found, but after screening, only 57 studies were included. The most common methodology employed for air quality data was through atmospheric transport models (specifically GEOS-Chem) (59.65%), followed by remote sensing through satellite imaging (50.88%), then by direct site monitors (33.33%). A single approach was used by 56.14%, while the rest employed a blended approach (43.86%), likely due to the inherent limitations of each data collection method, necessitating supplementary or novel approaches. However, the bulk of existing literature uses methods that are calibrated for the global north (75.44%), leaving behind the global south, which bears the brunt of air pollution health impacts due to its socioeconomic and geographic vulnerabilities, worsened by climate change. There is a need to recalibrate or validate these models to increase the reliability of results for the global south, as well as explore the possibility of further developing these air pollution modeling initiatives to not only contribute to surveillance, but directly further policy development and public health programming (i.e., the creation of early warning systems).

Air pollution from vegetation fire events in Thailand is a serious public health concern, particularly in the upper northern region. In response, several policies and measures have been implemented to control such fire events in this area. The objective of this study was to provide an update on the existing and current policies on vegetation fire events, their effects on air pollution and their influence on health by conducting a literature review and integrating the relevant information. The findings reveal that strict regulations prohibiting burning have had a significant effect on both air pollution and health after implementation compared to other policies. Despite increased evidence of short-term health effects from air pollution from vegetation fires, there is a need for additional research on chronic effects as well as studies that consider longer-term interventions through policies and factors that might affect exposure levels when examining the beneficial effects of policies on health impacts. Filling these knowledge gaps will help better define the potential health impacts of policies on vegetation fire events and further identify specific preventive interventions to promote health in this region in the future.