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Formaldehyde is a common air pollutant of the indoor environment. It has a potential effect on the respiratory function of people and so studies have been performed to assess this using exposure methods with high concentrations of formaldehyde. However, epidemiology studies have shown its impact on allergic diseases at lower domestic levels. The aim of this study was to develop an exposure chamber to study effects of low controlled concentrations of formaldehyde. Concentrations in the chamber were quantified by a simple DNHP-derivatisation method followed by liquid chromatography coupled to UV detection. Experiments to assess formaldehyde generation yield and reproducibility of formaldehyde levels in the chamber were performed in an empty chamber. The temporal decay of formaldehyde concentration in the exposure chamber was also investigated for more than 2h under different experimental conditions, for example in darkness or with somebody inside the chamber. Actual measured levels of formaldehyde were found to be 78-91% of the calculated value expected. The study of the temporal decay showed that subject’s breathing accounted for the fate of approximately 50% of the formaldehyde lost. Leaks, wall deposition, photolysis and adsorption on clothes were processes identified to explain the remaining 50%. However, this study has shown that both homogeneity and stability of formaldehyde concentration in the gas phase can be maintained acceptably to carry out future human exposure experiments.

Adsorption studies of acetone on pure ice surfaces obtained by water freezing or deposition or on frozen ice surfaces doped either with HNO3 or H2SO4 have been performed using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted over the temperature range 203-233 K and freezing solutions containing either H2SO4 (0.2 N) or HNO3 (0.2-3 N). Adsorption of acetone on these ice surfaces was always found to be totally reversible whatever were the experimental conditions. The number of acetone molecules adsorbed per ice surface unit N was conventionally plotted as a function of acetone concentration in the gas phase. For the same conditions, the amount of acetone molecules adsorbed on pure ice obtained by deposition are about 3-4 times higher than those measured on frozen ice films, H2SO4-doped ice surfaces lead to results comparable to those obtained on pure ice. On the contrary, N increases largely with increasing concentrations of nitric acid in ice surfaces, up to about 300 times under our experimental conditions and for temperatures ranging between 213 and 233 K. Finally, the results are discussed and used to reestimate the partitioning of acetone between the ice and gas phases in clouds of the upper troposphere.

The uptake kinetics of gaseous ClONO2 and BrONO2 on aqueous surfaces were measured, as a function of temperature and liquid composition (pure water and NaCl or NaBr containing solutions) using the droplet train technique coupled to a mass spectrometer. The uptake kinetics are driven by the reactivity of these gases and, for both compounds, the uptake rates on pure water or on NaCl solutions (0.1M) are comparable. The uptake coefficient γ of ClONO2 does not depend on the temperature while that of BrONO2 increases slightly when the temperature is raised from 272 to 280K. For ClONO2 and BrONO2, the uptake rates increase on NaBr-doped droplets, enabling the estimation of the mass accommodation coefficient α. The corresponding values for α are 0.108±0.033 for ClONO2 and 0.063±0.021 for BrONO2 where the statistical errors correspond to ±2σ. The reactions of ClONO2 and BrONO2 on NaCl solutions lead respectively to the formation of Cl2 and BrCl. The uptake of ClONO2 on NaBr solutions generates BrCl as primary product, which in turn can react with NaBr to produce Br2. As expected, the only product of BrONO2 reaction on NaBr solution is Br2.

The aim of this study is to evaluate the effects of the use of reformulated and oxygenated gasoline fuel blends on the air quality of an European city. The oxygenated compound added is the ethyl-t-butyl ether (ETBE). To perform this study, a numerical modeling approach has been chosen and the impacts of these fuel blends have been evaluated in terms of relative impacts on daily average concentrations and hourly maximum daily concentrations of air pollutants. The urban region of Strasbourg–Kehl in the middle of the upper Rhine valley has been chosen as area of investigation, due to (1) the existence of numerous previous studies on the meteorology and air quality of the region and (2) to the availability of emission inventories performed in the laboratory. The period of investigation, 11 May 1998, corresponds to a photochemical ozone pollution episode during which ozone concentrations exceeded the information threshold of the ozone directive of the European Union, i.e. 180 μg m−3 as 1 hourly average. The hourly emission inventories for the 9–15 May 1998 (kilometric resolution) for the Great Strasbourg–Kehl Area have been modified to build 12 emission scenarios with the help of recent available emissions factors for these reformulated and oxygenated fuel blends. The scenarios have been established by varying the fraction of gasoline passenger cars (from 30% to 100%) using three fuel blends. The mesoscale model EZM, including the updated chemical mechanism RACM, has been used to calculate the pollutants concentrations. Photochemical simulations reveal that all scenarios lead to an increase of NO concentrations (0.2–2.8% for the average concentrations over the whole domain) and to a significant decrease of the CO and VOCs levels (1.1–5.4% and 1.3–7.3%, respectively, over the whole domain) during the episode. There was no significant trend for the NO2 levels. For the ozone concentrations, the reductions appear to be modest (0.1–1.3% for the average concentrations over the whole domain).

In the frame of the climatological project REKLIPwhich involves part of Switzerland, Germany and Franceand concerns the upper Rhine valley, an atmosphericemission inventory has been established with a spatialresolution of a square kilometer and a time resolutionup to one hour. Anthropogenic emissions of SO2, NOx,CO, HCl and volatile organic compounds (VOC) divided into thirty compounds or group of compounds as well as biogenic emissions of NMVOC have been taken into account for the year 1990. This inventory has been updated for the following years until 1993 and some hourly emissions inventories have been derived for a period of several days of September 1992,corresponding to a REKLIP intensive measurement campaign.

The heterogeneous chemistry of nitryl chloride and nitryl bromide by salt containing solutions was studied as a function of temperature in the range from 275 to 293 K with the wetted-wall flowtube combined with FTIR and mass spectrometry detection. Uptake coefficients and values of the product Hk1/2 on these saline solutions have been determined. For nitryl halides interacting with NaI and NaBr solutions, the values of the product Hk1/2 are respectively 4384.7±326.7 and 103.1±18.7 M atm-1 s-1/2 for nitryl chloride at 275 K and 544.2±94.7 and 47.7±15.2 M atm-1 s-1/2 for nitryl bromide at 278 K. When reacting with NaI or NaBr solutions, these heterogeneous reactions release, as major products, the molecular forms of the halogen i.e., respectively I2 and Br2. A simplified reaction scheme explaining the formation of these products is presented and is inserted into a model simulating the chemistry in the marine boundary layer. The modelling effort showed Cl and BrO atoms concentrations up to 5×104 and 1.8×106 molecules cm-3 respectively, which are comparable to values actually measured in field campaigns.

Within the frame of an air quality study of the Great Casablanca Area (GCA), an atmospheric emission inventory concerning the major pollutants: SO2; NOx; non-methane volatile organic compounds (NMVOC); and CO has been realized. This inventory has a spatial resolution of 1 km2 and is established for the reference year 1992. The area, which covers 2500 km2 includes a region which is very sensitive to atmospheric pollution since it is heavily populated and contains up to 60% of the industrial activities of Morocco. The results, which include both biogenic and anthropogenic sources, show as expected very large emissions of pollutants mainly due to the presence of a refinery, several power plants and, contrary to the general European situation, the production of NOx is not dominated by road traffic.

The uptake kinetics of nitrosyl chloride (NOCl) by aqueous solutions has been measured as a function of temperature, using two different techniques, i.e., the wetted-wall at atmospheric and reduced...

A multiresidue analytical method is described for the analysis of 13 pesticides in fogwater, rainwater, gas, and particles. This method is based upon solid-liquid extraction using Sep-Pak tC18 light cartridges for aqueous samples, soxhlet for gas (adsorbed on XAD-2) and particles (on glass fiber filters), HPLC-based fractionation of the extracted residues using a silica column, and a linear gradient of n-hexane/tert butyl methyl ether followed by GC-ECD and HPLC-UV analyses of each fraction. Prior to analysis with GC-ECD, a methylation procedure using BF3/methanol was developed for the analysis of the fraction which contains chlorophenoxy acid herbicides. The recoveries of the extraction procedure of liquid samples and of the methylation were greater than 92 and 97% with a standard deviation lower than 8 and 5%, respectively. The detection limits varied between 0.1 and 0.01 microgram.ml-1 for the 13 pesticides studied with a standard deviation less than 9%. This method was used for the determination of pesticides in 18 fogwater samples (soluble + insoluble), 31 rainwater samples, and 17 air (gas + particles) samples collected between 1991 and 1993 in Colmar (east of France).

The concentrations in the soluble and total (soluble + insoluble) fractions of Mg, Ca, Fe, Mn, Zn, Al, Cd and Pb have been analysed by “inductively coupled plasma (ICP)” in 14 fog events collected in 1992 at an urban site in France (Strasbourg). For each fog event, two droplet size categories (2–6 μm and 5–8 μm) have been collected separately. For the analysis of the polyvalent cations in the soluble and total fractions, an analytical procedure using ICP and filtration on cellulose/PVC filters has been developed. The study of the solubility of some polyvalent cations has shown that two of the most important factors controlling the partitioning between the soluble and insoluble fraction are the nature of the particles and the pH of the fogwater. The influence of pH depended on the element. The solubility of Pb, Cd, Al, Fe, Mg, and Ca were pH dependent whereas, Zn and Mn solubility varied but no relationship with pH existed, ranging between 25 and 100% and 10 and 100%, respectively. On the other hand, Mg, Pb and Ca were predominantly present in the soluble phase, whereas Al was prevalent in the insoluble fraction. In the case of Cd and Fe., the presence in the soluble or insoluble phase depended largely on the fogwater pH.

The heterogeneous chemistry, on aqueous surfaces, of a series of acid halides, COF[sub 2], CF[sub 3]COF, and CF[sub 3]-COCl, was studied. The technique used consists of a low-pressure flow tube reactor in which a stream of monodisperse droplets interacts with the gaseous acid halide. The experiments, which were performed as a function of the initial pH of the droplets, temperature, and gas/liquid interaction time, yield low uptake coefficients in the range 5 [times] 10[sup [minus]4] to 5 [times] 10[sup [minus]3] and allow estimation of the product H[radical]k, where H is the Henry's law constant and k is the hydrolysis rate constant. The values reported here are 60, 60, and 350 M[center dot]atm[sup [minus]1] s[sup [minus][1/2]] for CF[sub 3]COCl, CF[sub 3]COF, and COF[sub 2], respectively, at 273 K. Separate values of H and k are also reported. The results show slightly different behavior between the chloride and the fluorides as a function of temperature. This study shows Henry's law and hydrolysis rate constants large enough that heterogeneous reactions on aqueous surfaces will limit the residence time of these species in the atmosphere. 25 refs., 8 figs., 1 tab.

We present here experimental determinations of mass accommodation coefficients β using a low pressure tube reactor in which monodispersed droplets, generated by a vibrating orifice, are brought into contact with known amounts of trace gases. The uptake of the gases and the accommodation coefficient are determined by chemical analysis of the aqueous phase. We report in this article measurements of βexp=(6.0±0.8)×10−2 at 298 K and with a total pressure of 38 Torr for SO2, (5.0±1.0)×10−2 at 297 K and total pressure of 52 Torr for HNO3, (1.5±0.6)×10−3 at 298 K and total pressure of 50 Torr for NO2, (2.4±1.0)×10−2 at 290 K and total pressure of 70 Torr for NH3. These values are corrected for mass transport limitations in the gas phase leading to β=(1.3±0.1)×10−1 (298 K) for SO2, (1.1±0.1)×10−1 (298 K) for HNO3, (9.7±0.9)×10−2 (290 K) for NH3, (1.5±0.8)×10−3 (298 K) for NO2 but this last value should not be considered as the true value of β for NO2 because of possible chemical interferences. Results are discussed in terms of experimental conditions which determine the presence of limitations on the mass transport rates of gaseous species into an aqueous phase, which permits the correction of the experimental values.

The uptake kinetics of nitrosyl chloride (NOCl) by aqueous solutions has been measured as a function of temperature, using two different techniques, i.e., the wetted-wall at atmospheric and reduced...

Uptake of acetaldehyde on ice surfaces has been investigated over the temperature range 203-253 K using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted on pure ice surfaces and on liquid/solid ice mixture both doped with nitric acid (0.063, 0.63, and 6.3 wt %). Uptake of acetaldehyde on these surfaces was always found to be totally reversible whatever the experimental conditions were. The number of acetaldehyde molecules adsorbed per surface unit was conventionally plotted as a function of acetaldehyde concentration in the gas phase. Although the amounts of acetaldehyde adsorbed on solid ice surfaces (pure and HNO(3)-doped ice) were approximately similar and rather limited, the number of acetaldehyde molecules taken up on the HNO(3)-doped solid ice/liquid mixtures are significantly higher, up to 1 or 2 orders of magnitudes compared to pure ice surfaces. At 213 K for example and for low concentrations of acetaldehyde (

Enthalpies and free energies of gas-phase clustering of one to ten water molecules about one acid molecule are predicted from thermodynamic considerations. The enthalpy of formation of the monohydrate, H 2 SO 4 H 2 O, −53.5 kJ/mol, compare favorably with recent calculations from quantum mechanics, −67 kJ/mol.

Aldehydes and BTEX concentrations were measured in 20 university libraries in Strasbourg (east of France) using Radiello passive sampling systems containing either DNPH or activated charcoal for aldehydes and BTEX, respectively. For the aldehydes, the conventional DNPH-derivatization method was used, followed by liquid chromatography coupled to UV detection while the BTEX were quantified by GC-PID. Aldehydes levels found inside the libraries ranged from 8.6 to 94.5 μg · m×3 for formaldehyde, 3.7 to 25.9 μg · m-3 for acetaldehyde, 2.1 to 58.8 μg · m-3 for hexanal, 0.2 to 5.3 μg · m-3 for benzaldehyde, and 0.7 to 16.3 μg · m-3 for propionaldehyde. Their mean values are 28.6± 18.8 μg · m-3 (formaldehyde), 10.2 ± 5.8 μg · m-3 (acetaldehyde) and 15.1 ± 12.1 μg · m-3 (hexanal), 1.1 ±1.1 for benzaldehyde and 2.8 ±3.3 for propionaldehyde, where the quoted errors correspond to 1σ level. Total BTEX concentrations were quantified in the same libraries and were usually relatively low ( -3) in all libraries, except for one where unusually high values (~295 μg · m-3) were found. Excluding this latter, the means BTEX concentrations were (in units of μg · m-3): 0.2 ±0.2 (benzene), 3.8 ±2.6 (toluene), 0.8 ±0.5 (ethyl benzene), 1.9 ± 1.2 (m- and p-xylenes), and 0.5 ±0.4 (o -xylene), where the quoted errors correspond again to 1σ.

Aldehydes concentrations were measured in 162 homes in the Strasbourg area (East of France) in the context of a case/control study pairing asthmatic and non-asthmatic people. The surveyed people have completed a questionnaire aiming to characterize the indoor homes and the people life practices. Gaseous aldehyde levels were quantified by a conventional DNHP-derivatization method followed by HPLC/UV. Formaldehyde, acetaldehyde and hexanal were the main encountered aldehydes with mean concentrations of 32.2±14.6, 14.3±9.7 and 8.6±8.1 μg m −3 , respectively, while propionaldehyde and benzaldehyde concentrations were usually −3 . The aldehydes concentrations simultaneously measured in both bedroom and living room were not significantly different except for formaldehyde and were correlated between them meaning that indoor air was quite homogenous in homes. Combination of information collected in our questionnaires and statistical analysis was used to investigate indoor aldehydes determinants. Even if formaldehyde sources are theoretically well identified, they are multiple so that it was difficult to determine the main parameters influencing its concentrations in domestic environment. Higher hexanal concentrations were related to new coatings such as painting, wallpapers and laminate floorings. Hexanal concentration decreased with both coating and furniture ages so that this compound may be considered as a tracer of these emissions.

Uptake of ethanol either on pure frozen ice surfaces or supercooled solutions doped with HNO3 (0.63 and 2.49 wt %) has been investigated using a coated wall flow tube coupled to a mass spectrometric detection. The experiments were conducted over the temperature range of 213-243 K. Uptake of ethanol on these surfaces was always found to be totally reversible whatever were the experimental conditions. The number of ethanol molecules adsorbed per surface unit was conventionally plotted as a function of ethanol concentration in the gas phase and subsequently analyzed using Langmuir's model. The amount of ethanol molecules taken up on nitric acid doped-ice surfaces was found to increase largely with increasing nitric acid concentrations. For example at 223 K, and for an ethanol gas-phase concentration of 1x10(13) molecules cm3, the number of adsorbed molecules are (in units of molecules cm-2): approximately 1.3x10(14) on pure ice; approximately 1.4x10(15) on ice doped with HNO3 0.63 wt %; approximately 7.5x10(15) on ice doped with HNO3, 2.49 wt %, i.e. 60 times larger than on pure ice. Since, according to the shape of the isotherms, the adsorption did not proceed beyond monolayer coverage, the enormous increase of ethanol uptake was explained by considering its dissolution in either a supercooled liquid layer (T230 K) or a liquid solution (T230 K). The formation of both was indeed favored by the presence of the HNO3. Our experimental results suggest that the amount of ethanol dissolved in such supercooled solutions follows Henry's law and that the Henry's law constants at low temperatures, i.e., 223-243 K, can be estimated by extrapolation from higher temperatures. Such supercooled solutions which exist in the troposphere either in deep convective clouds or in mixed clouds for temperature above 233 K, might be responsible for the scavenging of large amounts of soluble species, such as nitric and sulfuric acids, oxygenated VOCs including alcohols, carboxylic acids, and formaldehyde.

Formaldehyde and acetaldehyde concentrations have been measured in indoor environments of various public spaces (railway station, airport, shopping center, libraries, underground parking garage, etc.) of Strasbourg area (east of France). In addition, formaldehyde, acetaldehyde propionaldehyde and hexanal concentrations have been measured in 22 private homes in the same area. In most of the sampling sites, indoor and outdoor formaldehyde and acetaldehyde concentrations were measured simultaneously. Gaseous aldehydes levels were quantified by a conventional DNHP-derivatization method followed by liquid chromatography coupled to UV detection. Outdoor formaldehyde and acetaldehyde concentrations were both in the range 1–10 μg m −3 , the highest values being measured at the airport and railway station. Indoor concentrations were strongly dependant upon the sampling sites. In homes, the average concentrations were 37 μg m −3 (living rooms) and 46 μg m −3 (bedrooms) for formaldehyde, 15 μg m −3 (living rooms) and 18 μg m −3 (bedrooms) for acetaldehyde, 1.2 μg m −3 (living rooms) and 1.6 μg m −3 (bedrooms) for propionaldehyde, 9 μg m −3 (living rooms) and 10 μg m −3 (bedrooms) for hexanal. However, concentrations as high as 123, 80 and 47 μg m −3 have been found for formaldehyde, acetaldehyde and hexanal respectively. In public spaces, the highest formaldehyde concentration (62 μg m −3 ) was found in a library and the highest concentration of acetaldehyde (26 μg m −3 ) in the hall of a shopping center. Additional measurements of formaldehyde and acetaldehyde were made inside a car both at rest or in a fluid or heavy traffic as well as in a room where cigarettes were smoked. Our data have been discussed and compared with those of previous studies.

Adsorption study of acetic acid on ice surfaces was performed by combining experimental and theoretical approaches. The experiments were conducted between 193 and 223 K using a coated wall flow tube coupled to a mass spectrometric detection. Under our experimental conditions, acetic acid was mainly dimerized in the gas phase. The surface coverage increases with decreasing temperature and with increasing concentrations of acetic acid dimers. The obtained experimental surface coverages were fitted according to the BET theory in order to determine the enthalpy of adsorption deltaH(ads) and the mololayer capacity N(M(dimers)) of the acetic acid dimers on ice: deltaH(ads) = (-33.5 +/- 4.2) kJ mol(-1), N(M(dimers)) = (l1.27 +/- 0.25) x 10(14) dimers cm(-2). The adsorption characteristics of acetic acid on an ideal ice I(n)(0001) surface were also studied by means of classical molecular dynamics simulations in the same temperature range. The monolayer capacity, the configurations of the molecules in their adsorption sites, and the corresponding adsorption energies have been determined for both acetic acid monomers and dimers, and compared to the corresponding data obtained from the experiments. In addition, the theoretical results show that the interaction with the ice surface could be strong enough to break the acetic acid dimers that exist in the gas phase and leads to the stabilization of acetic acid monomers on ice.

International audience; Adsorption study of ethanol on ice surfaces were performed by combining experimental and theoretical approaches. The experiments were conducted using a coated wall flow tube coupled to a mass spectrometric detection. The surface coverage increases with decreasing temperature and with increasing ethanol concentrations. The obtained experimental surface coverages were fitted according to the B.E.T. theory in order to determine the enthalpy of adsorption ∆H ads and the monolayer capacity N M : ∆H ads =-57 ± 8 kJ mol-1 , N M = (2.8 ± 0.8)×10 14 molecule cm-2. The adsorption characteristics of ethanol on a proton disordered Ih(0001) ice surface were also jointly studied by performing classical molecular dynamics simulations. More specifically, the configurations of the molecules in their adsorption sites and the corresponding adsorption energies have been studied as a function of temperature and coverage. In the simulations, the saturation coverage is around N M = 3.2×10 14 molecule cm-2 , and corresponds to an adsorption energy equal to-56.6 kJ mol-1 , in good agreement with the experimental value. The results are discussed and compared with previous determinations for alcohols.

The uptake kinetics of gaseous ClONO2 and BrONO2 on aqueous surfaces were measured, using the droplet train technique coupled to a mass spectrometer, as a function of temperature and liquid composition (pure water and NaCl or NaBr containing solutions). The uptake kinetics are driven by the reactivity of these gases and, for both compounds, the uptake rates on pure water or on NaCl solutions (0.1 M) are comparable. The uptake coefficient γ of ClONO2 does not depend on the temperature while that of BrONO2 increases slightly when the temperature is raised from 272 to 280 K. For ClONO2 and BrONO2, the uptake rates increase on NaBr-doped droplets, enabling the estimation of the mass accommodation coefficient α. The corresponding values for α are 0.108±0.001 for ClONO2 and 0.063±0.009 for BrONO2. The reactions of ClONO2 and BrONO2 on NaCl solutions lead, respectively to the formation of Cl2 and BrCl. The uptake of ClONO2 on NaBr solutions generates BrCl as primary product, which in turn can react with NaBr to produce Br2. As expected, the only product of BrONO2 reaction on NaBr solution is Br2.

Adsorption studies of acetone and of 2,3-butanedione on ice surfaces were performed using a new vertical coated wall flow tube coupled to a mass spectrometric detection. Adsorption of acetone on ice was found to be totally reversible for ice temperatures ranging from 193 to 223 K and for gas phase acetone concentrations varying between 5.4 × 1010 and 6.4 × 1013 molecules cm−3. Adsorption of 2,3-butanedione was also reversible at 213 and 223 K but partially irreversible at 193 and 203 K when its concentrations were larger than 1 × 1013 molecules cm−3. It was shown that, at 203 K, the surface coverage increases when the ice surface contains large and dense cracks but is independent of the presence of cracks at 223 K. The surface coverage also increases with decreasing temperature and with increasing acetone or 2,3-butanedione concentrations. The obtained experimental surface coverages were fitted according to the Langmuir and BET theories in order to determine the enthalpy of adsorption ΔHads and the monolayer capacity NM. The following values of NM were derived (in units of 1014 molecule cm−2): NM = 1.3 ± 0.2 for acetone and NM = 1.2 ± 0.5 for 2,3-butanedione. The corresponding enthalpies of adsorption are (in kJ mol−1): −49 ± 7 for acetone and −59 ± 8 for 2,3-butanedione. The results are discussed and compared with previous determinations for acetone. Finally, the obtained results are used to estimate the partitioning of acetone between the ice and gas phases in clouds of the upper troposphere.

Uptake measurements of ethanol were performed to provide experimental values for a theoretical approach of its incorporation into a water droplet. The uptake coefficients of ethanol on pure water w...

In this article, a model which examines the formation and evolution of chemiions in an aircraft engine is proposed. This model which includes chemiionisation, electron thermo-emission, electron attachment to soot particles and to neutral molecules, electron-ion and ion-ion recombination, ion-soot interaction, allows the determination of the ion concentration at the exit of the combustor and at the nozzle exit of the engine. It also allows the determination of the charge of the soot particles. For the engine considered, the upper limit for the ion emission index EIi is of the order of (2-5) x1016 ions/kg-fuel if ion-soot interactions are ignored and the introduction of ion-soot interactions lead about to a 50% reduction. The results also show that most of the soot particles are either positively or negatively charged, the remaining neutral particles representing approximately 20% of the total particles. A comparison of the model results with the available ground-based experimental data obtained on the ATTAS research aircraft engines during the SULFUR experiments (Schumann, 2002) shows an excellent agreement.

A continuous flow diffusion cloud chamber has been used to study the growth of water droplets on NaCl aerosols of known size. Settling distances of droplets in the chamber have been recorded and compared to the theoretical ones generated on a computer. Using the droplet growth theory of Fukuta and Walter and a thermal accommodation coefficient of 1.0, the condensation coefficient was found to be 0.01.