Evaluating the feasibility of estimating particulate mass emissions of older-model diesel vehicle using smoke opacity measurements.

Real-world emissions of particulate matter (PM) and smoke opacity were studied for an older-model diesel pickup truck during four types of driving tests, namely fixed-point test, snap-acceleration test, road test, and hill road test (uphill/downhill). A portable emissions measurement system (PEMS) and an opacimeter were used to measure real-time concentrations of PM and smoke opacity, respectively, and simultaneously. Correlation analysis showed a significant positive association between PM and opacity, suggesting the feasibility of using an opacimeter to estimate PM mass emissions from diesel vehicles.

Intermodal comparison of commuters' exposure to VOCs between public, private, and active transportation.

Urban populations are exposed to a multitude of traffic-related air pollutants during daily commutes. This study assessed commuters' exposure to volatile organic compounds (VOCs) during bus, motorcycle, and bicycle commuting, and estimated the VOC inhalation dose. Benzene, toluene, ethylbenzene, and xylene (BTEX) were the main compounds detected, contributing 58 - 68% to ΣVOC (sum of the concentrations of all detected VOCs) in different travel modes.

Effect of lockdown and associated mobility changes amid COVID-19 on air quality in the Kathmandu Valley, Nepal.

The COVID-19 pandemic caused a setback for Nepal, leading to nationwide lockdowns. The study analyzed the impact of lockdown on air quality during the first and second waves of the COVID-19 pandemic in the Kathmandu Valley. We analyzed 5 years of ground-based air quality monitoring data (2017-2021) from March to July and April to June for the first and second wave lockdowns, respectively.

Wintertime Air Quality across the Kathmandu Valley, Nepal: Concentration, Composition, and Sources of Fine and Coarse Particulate Matter.

The Kathmandu Valley in Nepal experiences poor air quality, especially in the dry winter season. In this study, we investigated the concentration, chemical composition, and sources of fine and coarse particulate matter (PM, PM, and PM) at three sites within or near the Kathmandu Valley during the winter of 2018 as part of the second Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE 2). Daily PM concentrations were very high throughout the study period, ranging 72-149 μg m at the urban Ratnapark site in Kathmandu, 88-161 μg m at the suburban Lalitpur site, and 40-74 μg m at rural Dhulikhel on the eastern rim of the Kathmandu Valley.

Effects of driving behavior on real-world emissions of particulate matter, gaseous pollutants and particle-bound PAHs for diesel trucks.

This study employed a portable emissions measurement system to investigate the effects of vehicle attributes, driving behavior, and road grade on real-world emissions of particulate matter (PM), regulated gaseous pollutants, and particle-bound polycyclic aromatic hydrocarbons (PAHs) for old-model diesel trucks (model year 1995-2006, 6.7-35.0 metric ton) with little to no tailpipe emission control.

Comparative investigation of coal- and oil-fired boilers based on emission factors, ozone and secondary organic aerosol formation potentials of VOCs.

Volatile organic compounds (VOCs) are the important precursors of the tropospheric ozone (O) and secondary organic aerosols (SOA), both of which are known to harm human health and disrupt the earth's climate system. In this study, VOC emission factors, O and SOA formation potentials were estimated for two types of industrial boilers: coal-fired boilers (n = 3) and oil-fired boilers (n = 3). Results showed that ∑VOCs concentrations were more than nine times higher for oil-fired boilers compared to those for coal-fired boilers.