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This paper presents monitoring results of daily brick kiln stack emission and the derived emission factors. Emission of individual air pollutant varied significantly during a firing batch (7 days) and between kilns. Average emission factors per 1,000 bricks were 6.35-12.3 kg of CO, 0.52-5.9 kg of SO(2) and 0.64-1.4 kg of particulate matter (PM). PM emission size distribution in the stack plume was determined using a modified cascade impactor. Obtained emission factors and PM size distribution data were used in simulation study using the Industrial Source Complex Short-Term (ISCST3) dispersion model. The model performance was successfully evaluated for the local conditions using the simultaneous ambient monitoring data in 2006 and 2007. SO(2) was the most critical pollutant, exceeding the hourly National Ambient Air Quality Standards over 63 km(2) out of the 100-km(2) modelled domain in the base case. Impacts of different emission scenarios on the ambient air quality (SO(2), PM, CO, PM dry deposition flux) were assessed.

Biomass, one of the renewable resources, is expected to play an important role in the world’s energy future. In Asia, rice straw is an abundant agricultural surplus because rice is one of the leading staple food crops in the region. Often, rice straw is burned directly in the field via uncontrolled combustion methods that emit large amounts of short-lived air pollutants, greenhouse gases, and other pollutants. In Vietnam, the energy and environment protection sectors are facing great challenges because of rapid urbanisation and industrialisation. A national strategic choice is to exploit renewable energy, including biomass-derived energy, to achieve energy security and CO2 emission reduction. This study investigates the potential of rice straw as an energy source for power plants at a local scale in Vietnam using data derived from satellite Sentinel-1 images. The results show that Vietnam can produce 2,565 MW from rice straw, for which 24 out of 63 provinces have a potential capacity higher than 30 MW, and the Kien Giang province has the highest capacity (245 MW). The study also analyses limitations and obstacles overcoming which can promote the biomass energy sector in the country.

Samples of 24 h PM 10 and PM 2.5 were collected at a mountainous rural site of Tamdao, Vietnam, using collocated dichotomous and MiniVol samplers. The sampling was done in wet season (20 September-8 October 2005), dry season (17 December 2005-18 January 2006) and transitional season (5 April-26 April 2010). A pair of PM 2.5 and PM 10-2.5 or PM 10 samples was collected on a sampling day using quartz and mixed cellulose filters for each size fraction. The samples were analyzed for mass, BC, water soluble inorganic ions and elemental compositions. Higher PM 2.5 levels were obtained during dry season, at an average of 51 µg/m 3 , followed by the transitional season, 33 µg/m 3 , and the lowest in wet season, 25 µg/m 3 . The ratios between anions and cations, both in equivalence, were all below 1.0, but was higher for PM 2.5 than for PM 10-2.5 . The ammonium balance showed a good agreement between measured and estimated levels for PM 2.5 , suggesting that most of sulfate and nitrate were in their ammonium salts. The reconstructed mass showed high contributions from secondary inorganic particles, OM-biomass (estimated based on K + ), crustal and soot groups, which accordingly helped to reveal major contributing sources. Specifically, the high K-biomass and OM-biomass mass group in the dry season indicated the important contribution from biomass burning. The regional transport from surrounding territories to the site was investigated using 5-day HYSPLIT backward trajectories. The differences in PM mass and compositional species that were statistically significant between the seasons for similar trajectory patterns, or between patterns within a season, suggested the effects of seasons and/or air mass trajectory pathways on PM pollution. The northeast continental type of air masses observed in the dry season, with the longest continental pathway and continental origin, was associated with the highest levels of PM mass and compositional species.

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In 2014, Pha Din (1466 m a.s.l.) was established as a Global Atmosphere Watch (GAW) regional station for aerosol and trace gas measurements in northwestern Vietnam. This study presents a five-year climatology of aerosol optical properties derived from nephelometer and aethalometer measurements and a comparison with ground-based remote sensing measurements at the nearby AERONET station Son La. The annual variations of the aerosol measurements at Pha Din are clearly dominated by annually recurring periods with high biomass burning activity in northern Southeast Asia (February-May). During these periods, the majority of air masses arriving at Pha Din originate from the southwest (northern Thailand, Laos and Myanmar). Both the meteorological conditions and the aerosol optical properties are very similar during the individual high biomass burning periods (increased temperature: > 20°C; moderate ambient relative humidity: 60-70%; decreased single scattering albedo: 0.8-0.9; increased absorption Ångström exponent: 1.6-2.0; and scattering Ångström exponent significantly larger than 1). Prior to the biomass burning season (October-January), the meteorological conditions at Pha Din are influenced by the SE Asian monsoon, leading to a frequent transport of air masses from SW China with moderate aerosol loadings. The lowest pollution levels are observed from June to September, which represents the wet season.

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