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Ambient ammonia (NH3) measurements were performed with a mobile platform in three European cities: Zurich (Switzerland), Tartu (Estonia) and Tallinn (Estonia) deploying an NH3 analyzer based on cavity ring-down spectroscopy. A heated inlet line along with an auxiliary flow was used to minimize NH3 adsorption onto the inlet walls. In addition, a detailed characterization of the response and recovery times of the measurement system was used to deconvolve the true NH3 signal from the remaining adsorption-induced hysteresis. Parallel measurements with an aerosol mass spectrometer were used to correct the observed NH3 for the contribution of ammonium nitrate, which completely evaporated in the heated line at the chosen temperature, in contrast to ammonium sulfate. In this way a quantitative measurement of ambient gaseous NH3 was achieved with sufficient time resolution to enable measurement of NH3 point sources with a mobile sampling platform. The NH3 analyzer and the aerosol mass spectrometer were complemented by an aethalometer and various gas-phase analyzers to enable a complete characterization of the sources of air pollution, including the spatial distributions and the regional background concentrations and urban increments of all measured components. Although at all three locations similar increment levels of organic aerosols were attributed to biomass burning and traffic, traffic emissions clearly dominated the city enhancements of NH3, equivalent black carbon (eBC) and carbon dioxide (CO2). Urban increments of 3.4, 1.8 and 3.0 ppb of NH3 were measured in the traffic areas in Zurich, Tartu and Tallinn, respectively, representing an enhancement of 36.6, 38.3 and 93.8% over the average background concentrations. Measurements in areas strongly influenced by traffic emissions (including tunnel drives) were used to estimate emission factors (EF) for the traffic-related pollutants. The obtained median EFs range between 136.8-415.1 mg kg−1 fuel for NH3, 157.1–734.8 mg kg−1 fuel for eBC and 39.9–324.3 mg kg−1 fuel for HOA. Significant differences were found between the EFs of certain components in the three cities, which were partially linked to an older vehicle fleet in Estonia compared to Switzerland. Using the determined EFs we show that traffic can fully explain the NH3 enhancements in the three cities and also presents a non-negligible fraction of the background concentrations, which are mostly related to agricultural activities. Moreover, the estimated total contribution of traffic to NH3 at all three locations is in good agreement with the available emission inventories.

Air pollution is one of the main environmental concerns in urban areas, where anthropogenic emissions strongly affect air quality. This work presents the first spatially resolved detailed characterization of PM2.5 (particulate matter with aerodynamic equivalent diameter daero ≤ 2.5 µm) in two major Estonian cities, Tallinn and Tartu. The measurements were performed in March 2014 using a mobile platform. In both cities, the non-refractory (NR)-PM2.5 was characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) using a recently developed lens which increases the transmission of super-micron particles. Equivalent black carbon (eBC) and several trace gases including carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) were also measured. The chemical composition of PM2.5 was found to be very similar in the two cities. Organic aerosol (OA) constituted the largest fraction, explaining on average about 52 to 60 % of the PM2.5 mass. Four sources of OA were identified using positive matrix factorization (PMF): hydrocarbon-like OA (HOA, from traffic emissions), biomass burning OA (BBOA, from biomass combustion), residential influenced OA (RIOA, probably mostly from cooking processes with possible contributions from waste and coal burning), and oxygenated OA (OOA, related to secondary aerosol formation). OOA was the major OA source during nighttime, explaining on average half of the OA mass, while during daytime mobile measurements the OA was affected by point sources and dominated by the primary fraction. A strong increase in the secondary organic and inorganic components was observed during periods with transport of air masses from northern Germany, while the primary local emissions accumulated during periods with temperature inversions. Mobile measurements offered the identification of different source regions within the urban areas and the assessment of the extent to which pollutants concentrations exceeded regional background levels (urban increments). HOA, eBC, CO2, and CO showed stronger enhancements on busy roads during the morning and evening traffic rush hours; BBOA had its maximum enhancement in the residential areas during the evening hours and RIOA was enhanced in both the city center (emissions from restaurants) and in the residential areas (emissions from residential cooking). In contrast, secondary components (OOA, sulfate (SO4), nitrate (NO3), ammonium (NH4), and chloride (Cl)) had very homogeneous distributions in time and space. We were able to determine a total PM2.5 urban increment in Tartu of 6.0 µg m−3 over a regional background concentration of 4.0 µg m−3 (i.e., a factor of 2.5 increase). Traffic exhaust emissions were identified as the most important source of this increase, with eBC and HOA explaining on average 53.3 and 20.5 % of the total increment, respectively.

Waste burning is globally important emission source of several toxic compounds. The objective of this study was to acquire emission factors (EF) for PCDD/Fs, HCBs, PAHs, PMx and for several gaseous pollutants from the residential combustion, where wood is burned with municipal solid waste (MSW). In addition to the wood, paper and cardboard waste, people also tend to burn MSW. As the burnable waste content in MSW has changed during the past years, it is important to assess the effect of this factor for air emissions nowadays and in the past. Therefore an attempt was made to derive EF for the past emissions. 18 experiments including samples of firewood and MSW were burned using Estonian most common old type masonry heater, measuring PMx, PCDD/F, HCB, PAH-s and gaseous pollutants. Significant correlation was found between PCDD/F, HCl, HCB and CO and between HCl and HCB in all 18 experiments. In three experiments (years 1990, 1995, 2000), the mean levels of PCDD/F were higher than the legislative limit value for combustion of MSW in waste incineration plants. The mean PCDD/F concentrations during the experiments was 0.0833 (0.0116–0.1550 95% Cl) ng I-TEQ Nm −3 11% O 2 . Since low chlorine levels in used fuel caused high emissions of PCDD/F and HCB, it indicates that the habit of burning these kinds of waste in residential heaters should be avoided. We can conclude that RWC is significant source of PCDD/F, HCB and PAH. In general, EF measured within this study are in accordance with literature data. There was remarkable difference in EF between different years. EF of PCDD/F and HCB found confirm the trend of development of MSW collection system leading to an increasing usage of MSW recycling. Nevertheless, people's awareness about the negative impacts of waste burning in household heaters, should be raised.

Emissions from cattle farms in Estonia may vary from emissions in other regions of Europe due climatic differences and the housing systems used. Emission factors (EF) for the tie and loose housing systems for dairy farming were measured. Ammonia, odour and H2S emission measurements were made in tie and loose housing cattle farms with solid and liquid manure systems. Measurement were carried out in 2007 (10 different days from February to October) and in 2013 (in 30 different days in July–August). The gaseous EFs calculated for the tie housing cow building were 5.34 ± 0.47 kg [NH3] y−1 AU−1, 19.36 ± 4.39 g [H2S] y−1 AU−1 and for odour was 1.77 ± 3.06 OU y−1 AU−1. The EFs for the loose housing cow barn were 6.50 ± 4.01 kg [NH3] y−1 AU−1, 51.34 ± 30.34 g [H2S] y−1 AU−1 and for odour were 15.63 ± 20.96 OU y−1 AU−1. The NH3 and H2S EFs were validated through dispersion modelling against ambient levels measured in vicinity of the farms using passive samplers. An Eulerian advection-diffusion model with meteorological data was used to validate NH3 and H2S emission data. There was in general good correlation between measured and modelled levels for NH3 in both farms and for H2S in farm B. In general the EF were reliable and can be used in local and regional emission inventories and in dispersion calculations, but variation of emissions with temperature needs be taken into account. Further research is required to investigate emissions from more dairy farms over longer periods.

This study is aimed to assess the health impacts of outdoor PM2.5 concentrations to entire population of Estonia. As the air quality monitoring network in Estonia is rather sparse (six urban, three rural and a few industrial sites), the exposure assessment was based on long-term modelling, controlled by monitoring data from existing stations. The model runs were performed with IairViro modelling system, including the Eulerian MATCH model for country-wide run with 5 km grid resolution and AirViro urban model with 200 m grid resolution for five major cities. The database of pollution sources includes industrial, transport and domestic heating emissions. The average annual PM2.5 concentrations were found 7–9 μg/m3 at most of rural and in 9–13 μg/m3 typically at urban areas, up to 30 μg/m3 in some parts of capital city Tallinn. To estimate the health risks, the base-line national health statistics and exposure-response coefficients from previous epidemiological studies (ACS, APHEIS), were applied. It was found that on average 600 (CI 95 % 155–1,061) premature deaths per year are caused by PM2.5 pollution in Estonia, which has population nearly 1.3 million. On average 5 months of life are lost, maximum 14 months in some parts of Tallinn. About 900 additional hospitalizations due to pulmonary and cardiovascular diseases occur per year.

Oil shale combustion fly ash collected to electric precipitators from pulverized firing (PF) and circulating fluidized bed combustion (CFB) processes was investigated in atmospheric chamber experiments. The aim of the work was to detect differences in the atmospheric behaviour of the fine particles from CFB and PF boilers of the Estonian Power Plant (PP), located close to Narva, Estonia. One series of experiments was performed in a dual outdoor Teflon film smog chamber (270 m 3 ) at the University of North Carolina at Chapel Hill (USA) under normal weather conditions (temperature, humidity, sunlight). Parallel tests were carried out in an outdoor smog chamber (108 m 3 ) at Tuulna, Harju County, Estonia, where the experiment was made under meteorological conditions similar to those at the location of the PP. The size distribution and number concentration of particles in the chamber were monitored during the experiment. The fractional distribution results demonstrate that the CFB aerosol in the chamber air had more fine particles than the PF aerosol. Approximately 2 h after injection the fly ash particles larger than 4 µm had settled out from both samples. The initial fly ash aerosol had a trimodal fractional distribution. Both PF and CFB fly ash formed stable aerosols 1-3 µm in diameter during the 6 h experiment and are therefore prone to long-range transport.