Perception of indoor air quality (PIAQ) was evaluated in a nationwide survey of 567 French dwellings, and this survey was combined with measurements of gaseous and particulate matter (PM10 and PM2.5 ) indoor air pollutants and indoor climate parameters. The perception was assessed on a nine-grade scale by both the occupants of the dwellings and the inspectors who performed the measurements. The occupants perceived the air quality in their homes as more pleasant than the inspectors. The inspectors perceived the air quality as more unpleasant in dwellings in which the residents smoked indoors. Significant associations between PIAQ and indoor air pollutant concentrations were observed for both the inspectors and, to a lesser extent, the occupants. Introducing confounding parameters, such as building and personal characteristics, into a multivariate model suppressed most of the observed bivariate correlations and identified the tenure status of the occupants and their occupation as the parameters that most influenced their PIAQ. For the inspectors, perceived air quality was affected by the presence of smokers, the season, the type of ventilation, retrofitting, and the concentrations of acetaldehyde and acrolein.

Particle mass and number concentrations were measured in a mechanically ventilated classroom as part of a study of ventilation strategies for energy conservation. The ventilation system was operated either continuously, intermittently, or shut down during nights while it was on during workdays. It appears that the nighttime ventilation scheme is not important for indoor particle concentrations the following day if fans are operated to give five air exchanges in advance of the workday. The highest concentrations of PM10 were found during and after workdays and were due to human activity in the classroom. The average workday PM10 concentration was 14 μg/m(3) , well below the WHO guideline values. The number concentration of particles with diameter <0.750 μm was typically between 0.5 × 10(3) and 3.5 × 10(3)  particle/cm(3) . These concentrations were largely independent of the occupants. Transient formation of small particles was observed when ventilation was shut down. Then remaining ozone reacted with terpenes emitted by indoor sources and gave up to 8 × 10(3)  particle/cm(3) before formation stopped due to lack of ozone. The intermittent ventilation regime was found least favorable for the indoor air quality in the classroom.

Indoor air measurements were conducted in one unoccupied apartment of a ‘near-zero-energy’ residential building with a unique, wooden construction. Ozone, NO 2 , fine particles and volatile organic compounds, formaldehyde, acetaldehyde and peroxyacetyl nitrate (PAN) were measured under ‘as is’ conditions and after intentional intervention by adding ozone to simulate an ambient air ozone episode. Undisturbed concentrations were: O 3 5–10 ppb, NO 2 5–8 ppb, fine particles 2000–5000 cm −3 , formaldehyde 35 ± 5 µg/m 3 , PAN 0.3 ppb. During intervention, O 3 was 50–60 ppb, NO 2 15–20 ppb, fine particles 20,000–25,000 cm −3 , formaldehyde 44 ± 2 µg/m 3 and PAN 0.7–1 ppb. It was shown that chemical reactions had taken place in the indoor air. Ozone-initiated chemistry produced various aldehydes, PAN and, as a direct response to increased ozone concentrations, also fine particles. Calculations made by a simple model of PAN formation showed that an air change rate of around 0.2 h −1 would provide optimum conditions for PAN formation in a setting comparable to that of the investigated apartment. This air change rate is well below the Swedish national minimum of 0.5 h −1 . Further, the calculations show that the non-photochemical PAN formation could be a consequence of mixing ozone and nitrogen dioxide with terpenes and acetaldehyde.

UNLABELLED:The principle objective of the Danish research program 'Indoor Environment and Children's Health' (IECH) was to explore associations between various exposures that children experience in their indoor environments (specifically their homes and daycare centers) and their well-being and health. The targeted health endpoints were allergy, asthma, and certain respiratory symptoms. The study was designed with two stages. In the first stage, a questionnaire survey was distributed to more than 17,000 families with children between the ages of 1 and 5. The questionnaire focused on the children's health and the environments within the homes they inhabited and daycare facilities they attended. More than 11,000 questionnaires were returned. In the second stage, a subsample of 500 children was selected for more detailed studies, including an extensive set of measurements in their homes and daycare centers and a clinical examination; all clinical examinations were carried out by the same physician. In this study, the methods used for data collection within the IECH research program are presented and discussed. Furthermore, initial findings are presented regarding descriptors of the study population and selected characteristics of the children's dwellings and daycare centers.PRACTICAL IMPLICATIONS:This study outlines methods that might be followed by future investigators conducting large-scale field studies of potential connections between various indoor environmental factors and selected health endpoints. Of particular note are (i) the two-stage design - a broad questionnaire-based survey followed by a more intensive set of measurements among a subset of participants who have been selected based on their responses to the questionnaire; (ii) the case-base approach utilized in the stage 2 in contrast to the more commonly used case-control approach; (iii) the inclusion of the children's daycare environment when conducting intensive sampling to more fully capture the children's total indoor exposure; and (iv) all clinical examinations conducted by the same physician. We recognize that future investigators are unlikely to fully duplicate the methods outlined in this study, but we hope that it provides a useful starting point in terms of factors that might be considered when designing such a study.

Rate coefficients for the gas-phase reaction of isoprene with nitrate radical and with nitrogen dioxide were determined. A Teflon collapsible chamber with solid phase micro extraction (SPME) for sampling and gas chromatography with flame ionization detection (GC/FID) and a glass reactor with long-path FTIR spectroscopy were used to study the NO3 radical reaction using the relative rate technique with trans-2-butene and 2-buten-1-ol (crotyl alcohol) as reference compounds. The rate coefficients obtained are k(isoprene + NO3) = (5.3 +/- 0.2) X 10(-13) and k(isoprene + NO3) = (7.3 +/- 0.9) x 10(-13) for the reference compounds trans-2-butene and 2-buten-l-ol, respectively.The NO2 reaction was studied using the glass reactor and FTIR spectroscopy under pseudo-first-order reaction conditions with both isoprene and NO2 in excess over the other reactant. The obtained rate coefficient was k(isoprene + NO2) = (1.15 +/- 0.08) x 10(-19). The apparent rate coefficient for the isoprene and NO2 reaction in air when NO2, decay was followed was wed was (1.5 +/- 0.2) x 10(-19). The discrepancy is explained by the last formation of peroxy nitrates. Nitro- and nitrito-substituted isoprene and isoprene-peroxynitrate were tentatively identified products from this reaction.All experiments were conducted at room temperature and at atmospheric pressure in nitrogen or synthetic air. All rate coefficients are in units of cm(3) molecule(-1) s(-1), and the errors are three standard deviations from a linear least square analyses of the experimental data. (C) 2004 Wiley Periodicals, Inc.

Isoprene fluxes from a Salix viminalis (willow) plantation in western Sweden were measured using the relaxed eddy accumulation (REA) technique. Fluxes of up to 0.23μgm−2s−1 could be observed. A standard emission factor at 303K and a PAR flux of 1000μmolm−2 s−1 was estimated to 0.98μgm−2s−1 by using the G93 algorithm. The chemistry of an air parcel passing over a willow coppice plantation was investigated utilising a Lagrangian box model in which the measured isoprene fluxes were used as input data. Dispersion after the field was accounted for by a procedure based on the Gaussian plume model. The calculations indicate that, in most cases, the isoprene emissions have a small effect on the local air quality.

Fluxes of some Volatile Organic Compounds (VOC) from grass were measured at a golf course in western Sweden, using the Relaxed Eddy Accumulation (REA) technique. The sampling was done by collecting VOC onto adsorbent tubes and the analysis was performed by thermal desorption followed by GC/MS. High emissions were observed after cutting. Transient fluxes of (Z)-3-hexenyl acetate (0.51 mug m(-2) s(-1)), (Z)-3-hexen-1-ol (0.14 mug m(-2) s(-1)) and (Z)-3-hexenal (0.40 mug m(-2) s(-1)) were measured, even at low temperatures. The REA technique requires a relatively large fetch area that is sometimes not available. Therefore, a procedure for correcting measured fluxes from a limited fetch is suggested.

The oxidation of SO2 by O-3 on mineral dust was studied using dffiuse reflectance infrared Fourier transform spectroscopy (DRIFTS). Formation of sulfate was observed on the surface. A two-step mechanism that involves physisorbed SO2 followed by oxidation is presented. The formation rate was determined to be first order with respect to SO2 and zero order in O-3. The reactive uptake coefficient, gamma was determined from the infrared absorbance, that was calibrated by ion chromatography, and from the geometric or the BET surface area. gamma(SO2) was independent of the SO2 concentration and was determined to be in the order of 10(-3) using the geometric surface area, or 10(-7) using the BET surface area for [SO2] = 2.2 x 10(12) to 2.0 x 10(13) and [O-3] = 5.6 x 10(12) (in units of molecule cm(-3)). gamma(O3) depended linearly on the O-3 concentration and varied from 10(-2) to 10(-4) using the geometric area or 10(-6) to 10(-8) using the BET area for [O-3] = 1.9 x 10(12) to 5.5 x 10(13) and [SO2] = 5.4 x 10(12) (in units of molecule cm(-3)). In all experiments surface saturation was observed with an amount of 2 x 10(9) sulfate ions g(-1) on the mineral dust sample. In the presence of water vapor regeneration of active sites was observed. After several exposures to water vapor corresponding to 80% relative humidity and successive SO2 and O-3 treatments the amount of formed sulfate covering the surface was increased by 47% compared to the dry experiments.

Rate coefficients for the reaction between NO3 and acetaldehyde have been determined by the absolute rate fast-flow-discharge technique and by the relative rate method. The flow-tube experiments were carried out under pseudo-first-order conditions in NO3 over the temperature range 263–363 K using He as a carrier gas. The data suggests an activation energy of Ea/R = 1950 ± 290 K and k296 = (9.1 ± 0.8) × 10−15 cm3 molecule−1 s−1 (3 σ errors) as an upper limit. Mixing ca. 20% of oxygen in the He carrier gas resulted in Ea/R = 2020 ± 260 K and k296 = (2.5 ± 0.5) × 10−15 cm3 molecule−1 s−1. The relative rate experiments, performed in a static reactor employing long path FTIR detection, gave k298 = (2.62 ± 0.29) × 10−15 cm3 molecule−1 s−1, and showed a moderate kinetic isotope effect, kCH3CHO+NO3/kCH3CDO+NO2 = 2.37 ± 0.08 at 298 K. The differences in the reaction rate coefficients obtained by the two methods are analysed and discussed in terms of secondary reactions involving NO3 in the flow-tube. Model studies indicate that acetyl and peroxyacetyl radicals react with NO3 with rate coefficients of 2.5 × 10−11 and 1.5 × 10−13 molecule cm−3 s−1 at 296 K and 5 mbar, respectively. The reaction was also studied by quantum mechanical methods and the transition states for the abstraction of aldehydic and methylic hydrogen atoms were located. Their relative energies, calculated on the MP2/cc-pVDZ//CCSDT/cc-pVDZ level, conform to the reaction proceeding entirely through Hald-abstraction at room temperature.

Rate coefficients for the reaction of acrolein (prop-2-en-1-al), crotonaldehyde (but-2-en-1-al) and pivalaldehyde (2,2-dimethylpropanal) with chlorine atoms were determined. The resulting rate coefficients were (1.8 ± 0.3) × 10−10, (2.2 ± 0.4) × 10−10 and (1.2 ± 0.2) × 10−10 (cm3 molecule−1 s−1) for acrolein, crotonaldehyde and pivalaldehyde, respectively. Rate coefficients for chlorine atom reaction with propanal, butanal, 2-methylpropanal and trans-but-2-ene were determined to be (1.2 ± 0.2) × 10−10, (1.5 ± 0.3) × 10−10, (1.5 ± 0.3) × 10−10 and (3.0 ± 0.6) × 10−10 (cm3 molecule−1 s−1), respectively. The relative rate technique was used with propene as the reference compound. The experiments were carried out at 297 ± 2 K and 1020 ± 2 mbar using a 0.153 m3 borosilicate glass reactor with long-path FTIR spectroscopy as the analytical tool. Synthetic air and nitrogen were used as bath gases. Literature values of the corresponding hydroxyl and nitrate radical rate coefficients were confirmed. The chemical characteristics of the organic substances have a limited influence on the reactivity with Cl, a larger effect in the OH-case but are decisive for the NO3 reactions. Introduction of an aldehydic carbonyl group into an unsaturated compound reduces the reactivity of a neighboring double bond for reaction with all three radicals. The unsaturated aldehydes reacting with NO3 show a rate coefficient that is lower than both the corresponding simple alkene and aliphatic aldehyde, indicating that also the reactivity of the aldehydic hydrogen atom is affected. The results show that during the morning hours, Cl atoms may be the most significant oxidising agent for organic substances in urban coastal air.

Five structurally similar unsaturated alcohols, 2-propene-1-ol (allyl alcohol), 3-butene-2-ol, 2-methyl-3-butene-2-ol (MBO232), 2-butene-1-ol (crotyl alcohol) and 3-methyl-2-butene-1-ol (MBO321), were examined to clarify their atmospheric degradation pathways via oxidation initiated by NO3 radicals. The reactions were investigated using a 0.153 static glass reactor equipped with long-path FTIR spectroscopy. The experiments were performed at a pressure of 1020 +/- 5 mbar and at a temperature of 297 +/- 2 K in air or nitrogen as the bath gas. The identified and quantified gas phase products were small carbonyl compounds such as acetone, formaldehyde, acetaldehyde, glycolaldehyde and 2-nitrooxy acetaldehyde. The specific products and their yields varied for the five studied alcohols as follows: formaldehyde 37(+/- 1)% and 2-nitrooxy acetaldehyde 41(+/- 7)% from allyl alcohol; acetaldehyde 28(+/- 6)%, formaldehyde 2(+/- 1)% and 2-nitrooxy acetaldehyde 33(+/- 4)% from 3-butene-2-ol; acetone 63(+/- 6)% and 2-nitrooxy acetaldehyde 67(+/- 8)% from MBO232; acetaldehyde 12(+/- 2)%, formaldehyde 10(+/- 3)% and glycolaldehyde 7(+/- 2)% from 2-butene-1-ol; acetone 21(+/- 6)%, formaldehyde 11(+/- 3)% and glycolaldehyde 29(+/- 10)% from MBO321. In addition, yields were estimated for total organic nitrates using an average integrated absorption cross section of unspecified organic nitrates. Tentative reaction schemes were proposed from the yielded products. The distribution between bond breakage and other processes such as abstraction of a hydrogen atom from the alkoxy radical, formed in the degradation process, was estimated. The small carbonyl compounds were produced by the bond breakage mechanisms. Large multi-functional organic compounds e.g. 1-hydroxy-3-nitrooxy-3-methyl-2-butanone from MBO321 were proposed to be formed by hydrogen abstraction. From the product distribution, the contribution of the number of methyl group substituents at the alpha and gamma carbon atoms, influencing the bond breakage pattern, is discussed. The observed bond cleavage trends are correlated to a substitution pattern where electron donating methyl substituents increase the stability of the leaving radical groups.

HOCl is speculated to be an important intermediate in mid-latitude marine boundary layer chemistry and at high latitudes in spring-time when surface-level O-3 depletion occurs. However, techniques do not currently exist to measure HOCl in the troposphere. We demonstrate that atmospheric pressure ionization mass spectrometry (API-MS) is a highly sensitive and selective technique which has promise for HOCl measurements both in laboratory systems and in held studies. While HOCl can be measured as the (HOCl . O-2)(-) adduct with air as the chemical ionization (CI) reagent gas, the intensity of this adduct is sensitive to the presence of acids and to the amount of water vapor, complicating its use for quantitative measurements. However, the addition of bromoform vapor to the corona discharge region forms bromide ions that attach to HOCl and allow its detection via the (HOCl . Br)- adduct. The ion-molecule chemistry associated with the use of air or bromoform as the CI reagent gas is discussed, with particular emphasis on the effects of relative humidity and gas phase acid concentrations. HOCl is quantified by measuring the amount of Cl-2 formed by its heterogeneous reaction with condensed-phase HCl/H2O. Detection limits are similar to 3 parts per billion (ppb) using air as the CI reagent gas and similar to 0.9 ppb using bromoform. The atmospheric implications of this work are discussed.

HOCl is an important intermediate in stratospheric and tropospheric chemistry. Although it can be readily measured in laboratory systems at low pressures (less than or equal to 20 Torr) using conventional electron impact ionization mass spectrometry, there is a need for a measurement technique that can operate at higher pressures, up to 1 atm in air, One such technique seeing increasing use is atmospheric pressure ionization mass spectrometry (API-MS). We report here studies of the API-MS of similar to 0.5-50 ppm HOCl at a total pressure of 1 atm and room temperature. Major peaks from the ion-adducts with Cl- and OCl- were observed. The Br- adduct of HOCl can also be generated using bromoform in the discharge region of the ion source. At the lower range of HOCl concentrations studied in air, the O-2(-) adduct and small parent peaks assigned to HOCl- were observed. The species present as minor impurities in the HOCl source (Cl-2, Cl2O and HCl) can be readily distinguished through identification of the parent ion for Cl-2, or as their adducts with Cl- and Br- for Cl2O and HCl. The identification of HOCl was confirmed using electron impact ionization time-of-flight mass spectrometry (EI-MS). HOCl was quantified using EI-MS to measure the Cl-2 generated when the HOCl reacted heterogeneously on a water-ice/HCl surface and independently by photolysis of the HOCl to generate atomic chlorine, which was trapped using propene and measured as chloroacetone. The implications for the use of API-MS for measuring HOCl in laboratory systems and in ambient air are discussed.

The heterogeneous reactions of oxides of nitrogen with NaCl as a model for sea salt particles have been the focus of many studies, due to their potential to act as precursors to atomic halogens in the troposphere. While a great deal has been learned about the kinetics and mechanisms of NaCl reactions, it is not clear how well this extrapolates to the complex mixture of inorganics found in sea salt. We report here diffuse reflectance infrared Fourier transform spectrometry (DRIFTS) studies in which nitrate formation on the salt surface is followed with time during the reaction of gaseous NO2 with synthetic sea salt at 298 K in the presence of either He or air as the carrier gas. The infrared bands due to surface nitrate formed during the reaction of NO2 are shown to be similar to those from the reaction of MgCl2 . 6H(2)O, a major hydrate in the mixture which was used as a surrogate for all of the crystalline hydrates. Significant amounts of surface-adsorbed water are generated in the reaction of synthetic sea salt with NO2 in air, which appears at least in part to be due to liberation of bound water of hydration in the crystalline hydrates. The reaction order with respect to NO2 is (1.8 +/- 0.2) (2 sigma) when the reaction of the synthetic sea salt is carried out in He but only (1.2 +/- 0.2) (2 sigma) when air is used as the carrier gas. For comparison, the reaction order for the NO2-NaCl reaction was reexamined and found to be (1.8 +/- 0.3) (2 sigma) in He and (1.6 +/- 0.3) (2 sigma) in air, in agreement with previous work(19) using this technique. It is assumed for slopes greater than or equal to 1.6 that N2O4 is the reacting species for the purpose of expressing the kinetics in the usual form of reaction probabilities. For the N2O4-NaCl reactions in He and air, and for the N2O4-synthetic sea salt reaction in He, the reaction probabilities are similar (similar to 10(-4)). The reaction of synthetic sea salt with NO2 in the presence of air is treated in terms of a first-order reaction with NO2 being the reactive species, which gives a reaction probability for the NO2-synthetic sea salt reaction of similar to 10(-8). The atmospheric implications are discussed.

Rate coefficients for the reactions between NO3 and the chloroethenes have been determined by the fast-flow-discharge technique and by the relative rate method in a static reactor employing FTIR detection. The relative rate experiments were performed at 298 +/- 2 K and 1013 +/- 3 mbar in a nitrogen atmosphere with excess ethane as a chlorine scavenger. The how tube experiments were carried out under pseudo-first-order conditions in NO3. The temperature dependence of the NO3 reactions with chloroethene and trichloroethene was investigated over a temperature range of ca. 100 K, and their rate coefficients were fitted to Arrhenius expressions. A comparison between our measured rate coefficient data for the NO3 reaction with chloroethenes reveals that the relative rate results are up to 20% lower than those from the fast-flow-discharge experiments. Possible secondary reactions in the flow tube are discussed.

DMS is produced in large quantities by natural oceanic processes. Its chemistry and emissions have been postulated to play a role in the radiative balance of the atmosphere. While its reactions with OH and NO3 radicals are well known, the reaction with chlorine atoms in the marine boundary layer has also been suggested recently. If this produces CH3Cl, it would contribute to the global budget of this naturally occuring halocarbon. Experiments were carried out to measure the yield of CH3Cl in the Cl+DMS reaction. CH3Cl was indeed formed in this reaction in laboratory experiments at 1 atm. and 298 K, with a small yield of (1.34±0.07) × 10−3. This yield is sufficiently small that the contribution to the global CH3Cl budget is estimated to be ≤2% and it is unlikely to be responsible for the anomalously high CH3Cl concentrations measured recently over the Labrador Sea.

Rate coefficients for nitrate radical pas-phase reactions with prop-2-en-1-ol (allyl alcohol). but-1-en-3-ol, and 2-methylbut-3-en-2-ol have been determined. Both absolute (fast now discharge with diode laser detection of NO3) and relative (batch reactor and FTIR spectroscopy) rate techniques were used to measure the rate coefficients. The rate coefficients at 294 K are: (1.3 +/- 0.2) x 10(-14), (1.2 +/- 0.3) x 10(-14), and (2.1 +/- 0.3) x 10(-14) cm(3) molecule(-1) s(-1) for prop-2-en-1-ol, but-1-en-3-ol, and 2-methylbut-3-en-2-ol, respectively The activation energy for reaction of NO3 with prop-2-en-1-ol was determined to 2.8 +/- 2.5 kj mol(-1) in the temperature range between 273 and 363 K. The atmospheric importance of unsaturated alcohols and structure-reactivity considerations are also discussed. (C) 1996 John Wiley & Sons, Inc.