The oxidative potential (OP) of particulate matter (PM) is a major driver of PM-associated health effects. In India, the emission sources defining PM-OP, and their local/regional nature, are yet to be established. Here, to address this gap we determine the geographical origin, sources of PM, and its OP at five Indo-Gangetic Plain sites inside and outside Delhi. Our findings reveal that although uniformly high PM concentrations are recorded across the entire region, local emission sources and formation processes dominate PM pollution. Specifically, ammonium chloride, and organic aerosols (OA) from traffic exhaust, residential heating, and oxidation of unsaturated vapors from fossil fuels are the dominant PM sources inside Delhi. Ammonium sulfate and nitrate, and secondary OA from biomass burning vapors, are produced outside Delhi. Nevertheless, PM-OP is overwhelmingly driven by OA from incomplete combustion of biomass and fossil fuels, including traffic. These findings suggest that addressing local inefficient combustion processes can effectively mitigate PM health exposure in northern India.

Port environments are characterized by complex and highly variable emissions from shipping, industrial and traffic activities, which results in distinct spatial and temporal heterogeneity in air pollutant concentrations. Fuel cells used in port activities, whether stationary or mobile, can be adversely affected by elevated pollutant concentrations. Therefore, we investigate the concentrations of volatile organic compounds (VOCs), trace gases, and ultrafine particles in the Port of Rotterdam as part of the KaLiBer joint project. MOBILAB serves as the mobile measuring platform equipped with state-of-the-art instrumentation for particle and gas-phase analysis, enabling both mobile transects and stationary monitoring. VOCs were measured using proton-transfer-reaction mass spectrometry (PTR-MS), capturing a wide range of oxygenated and non-oxygenated species, alongside simultaneous observations of CO, CO₂, NOₓ, SO₂, NH₃, and ultrafine particle (UFP) number concentrations. The mobile measurements were conducted over 10 days along selected routes in the port area and subsequent 30 days of stationary monitoring during summer. PTR-MS measurements covered approximately 130 masses, allowing a detailed characterization of both oxygenated and non-oxygenated VOCs.The mobile measurements capture distinct spatial gradients and short-lived concentration spikes linked to local emission plumes. In contrast, the stationary data set reveals long-term variability and background conditions with additional plumes from ships passing by. Average concentrations and prominent diurnal patterns suggest distinct emission sources from shipping, heavy-duty traffic, and industrial activities. Spatial analysis reveals elevated VOC concentrations accompanied by high UFP and CO2 levels, along port roadways. This suggests a dominant contribution from traffic-related sources. In the urban background, mixing ratios decreased due to chemical transformation and atmospheric dilution. The aromatic-to-oxygenated VOC (OVOC) ratios reveal distinct differences between fresh emissions along traffic-affected routes and more chemically aged air masses at the stationary site. This emphasizes the dynamic interplay between primary emissions and atmospheric processing. Although toluene/benzene ratios were comparable during mobile and stationary periods, they reflect mixed contributions from traffic, shipping, and industrial sources.The combined mobile–stationary dataset demonstrates the significance of high-time-resolution measurements for capturing emission variability, chemical processing, and source contributions in complex port environments. Such insights are vital for quantifying transport-sector contributions to urban air pollution. They are essential for assessing potential health impacts, and effective emission mitigation and air quality management. Beyond atmospheric characterization, the observed concentration ranges, variability, and occurrence of short-lived pollutant peaks are important for designing and optimizing air filtration systems that protect fuel cell technology. In particular, understanding the temporal occurrence of VOCs and acidic gases is essential for minimizing catalyst poisoning, membrane degradation, and performance losses. This, in turn, improves fuel cell durability and operational lifetime under real-world port conditions.This work is funded by the Federal Ministry for Economic Affairs and Energy based on a resolution of the German Bundestag under funding code 03EN5043D.

The present study addresses a key gap in characterizing hyperlocal air quality across three contrasting land-use settings during the peak pollution season in a central city in the Indo-Gangetic Plain (CIGP). We conducted ~744 hours of hyperlocal measurements in Lucknow city, spanning the post-monsoon to winter season over 31 days, using a mobile ambient air quality monitoring platform (MAAQMP). Measurements were conducted at three contrasting land-use settings—a background Site (“Site 1”), a traffic corridor (“Site 2”), and a major industrial cluster (“Site 3”). High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) organic and inorganic mass spectra were subjected to Multilinear Engine-2, Positive Matrix Factorization (ME-2 PMF) source apportionment using a unified organic-inorganic aerosol (OA–IA) matrix. Across sites, NR-PM_2.5 was dominated by secondary organic aerosols (SOA), with biomass burning, traffic, and inorganic-associated organic factors (sulphate, nitrate-rich OA). Unlike Sites 1–2 (sulphate/low-volatility oxygenated organic aerosol (OOA)-dominant), Site 3 showed heterogeneous OA from biomass burning, semi-volatile/nitrate OOA, solid fuel, and traffic. Particle growth events (PGEs) were predominantly nocturnal, occurring under stable boundary-layer and inversion conditions. Site 3 exhibited ~5 times more nocturnal PGEs than the background, which was attributed to a higher condensation sink (CS). Stack vapors drive these PGEs (5–15 nm/h), enhancing the growth of oxidized biomass-burning organic aerosols (O-BBOA) and low-volatility OOA under inversions (r = 0.24). These results highlight the potential of near-source stationary van-based measurements for resolving hyperlocal aerosol growth processes and source influences.

The Indo-Gangetic Plain (IGP) experiences strong seasonal and spatial heterogeneity in aerosol composition, driven by variations in emissions, meteorology, and regional transport. Capturing these variations requires measurement approaches that extend beyond conventional fixed-site monitoring. In this study, we deployed a mobile lab platform equipped with aerosol instrumentation, including a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), to investigate seasonal variability in organic aerosol (OA) sources during the post-monsoon and spring seasons across distinct urban environments in Lucknow, located in the central Indo-Gangetic Plain.Field campaigns were conducted during the post-monsoon and spring seasons at Babasaheb Bhimrao Ambedkar University (BBAU), a site influenced by traffic near major highways, and at the Council of Scientific & Industrial Research–Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), located adjacent to a forested area. Additional measurements were conducted during the spring season at the Uttar Pradesh Pollution Control Board (UPPCB) site, which represents a residential–commercial environment.At each location, the mobile laboratory was operated for approximately 10–15 days, enabling continuous, near real-time characterization of fine particulate matter and associated co-pollutants. Measurements of non-refractory PM2.5 (NR-PM2.5) chemical composition (measured using HR-ToF-AMS) were supported by simultaneous observations of trace elements, black carbon, gaseous species, total PM2.5 mass, and meteorological parameters. This integrated, multi-instrument framework allowed for a consistent comparison of aerosol chemical signatures across sites and seasons, while capturing short-term variability linked to local emissions, atmospheric processing, and regional transport.Organic aerosol dominated the mass of NR-PM2.5 across all sites and seasons, contributing more than 50% of the total NR-PM2.5. Source apportionment using Positive Matrix Factorization (PMF) with the multilinear engine (ME-2) resolved hydrocarbon-like OA (HOA), biomass-burning OA (BBOA), oxidized biomass-burning OA (O-BBOA), and secondary oxygenated OA components (SVOOA and LVOOA). During the post-monsoon period, BBOA accounted for approximately 28–40% of total OA across the sites, indicating a strong combustion influence under shallow boundary-layer conditions. Traffic-related HOA contributed about 8–13% of OA, with enhanced fractions at the highway-influenced BBAU site, reflecting local vehicular emissions. In contrast, springtime conditions showed enhanced secondary OA contributions (70-60%), with trajectory-based analyses highlighting the role of long-range transport in shaping aerosol composition.The use of a mobile laboratory enabled rapid deployment across diverse land-use environments while maintaining consistent instrumentation and methodology, allowing robust inter-site and inter-seasonal comparisons. This approach emphasises the significance of high-resolution mobile observations for elucidating the fine-scale spatial variability and seasonal evolution of organic aerosol sources in the complex urban regions of the IGP.

The present study addresses a key gap in characterizing hyperlocal air quality across three contrasting land-use settings during the peak pollution season in a central city in the Indo-Gangetic Plain (CIGP). We conducted ~744 hours of hyperlocal measurements in Lucknow city, spanning the post-monsoon to winter season over 31 days, using a mobile ambient air quality monitoring platform (MAAQMP). Measurements were conducted at three contrasting land-use settings—a background Site (“Site 1”), a traffic corridor (“Site 2”), and a major industrial cluster (“Site 3”). High-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) organic and inorganic mass spectra were subjected to Multilinear Engine-2, Positive Matrix Factorization (ME-2 PMF) source apportionment using a unified organic-inorganic aerosol (OA–IA) matrix. Across sites, NR-PM_2.5 was dominated by secondary organic aerosols (SOA), with biomass burning, traffic, and inorganic-associated organic factors (sulphate, nitrate-rich OA). Unlike Sites 1–2 (sulphate/low-volatility oxygenated organic aerosol (OOA)-dominant), Site 3 showed heterogeneous OA from biomass burning, semi-volatile/nitrate OOA, solid fuel, and traffic. Particle growth events (PGEs) were predominantly nocturnal, occurring under stable boundary-layer and inversion conditions. Site 3 exhibited ~5 times more nocturnal PGEs than the background, which was attributed to a higher condensation sink (CS). Stack vapors drive these PGEs (5–15 nm/h), enhancing the growth of oxidized biomass-burning organic aerosols (O-BBOA) and low-volatility OOA under inversions (r = 0.24). These results highlight the potential of near-source stationary van-based measurements for resolving hyperlocal aerosol growth processes and source influences.