Ilias G. Kavouras

Formation of atmospheric particles from organic acids produced by forests

Aerosol formation in the atmosphere is an important process to understand, in that such particles may act as the cloud condensation nuclei responsible for the ‘cloud–climate’ effect, and could locally be hazardous to health. The number-concentration of total atmospheric aerosols and cloud condensation nuclei is largely contributed by organic aerosols. Much of the organic aerosol is formed from atmospheric gas-to-particle conversion, and the common and widespread non-methane hydrocarbons emitted by vegetation have been investigated as possible precursors. But strong evidence for a quantitative link between biogenic hydrocarbon emission and organic aerosol formation has so far been lacking. Here we present measurements of gaseous and particulate atmospheric species from a forested area to show that some hydrocarbons (for example, terpenes) emitted by vegetation are photo-oxidized to organic acids (for example, pinonic acids), which condense to form organic aerosols. Thus the forests, through their production of large quantities of organic aerosols, could be of considerable significance both for climate (through cloud-condensation-nuclei formation) and for heterogeneous atmospheric chemical processes.

Measurement of particulate aliphatic and polynuclear aromatic hydrocarbons in Santiago de Chile : source reconciliation and evaluation of sampling artifacts

Abstract Using a novel sampler, particulate organic compounds were collected in Santiago de Chile from June 9 to August 10, 1997. This sampler consists of a diffusion denuder to remove gas-phase organics prior to particle collection, a Teflon filter, and a PUF cartridge downstream of the filter. PAHs and n -alkanes were measured using gas chromatography/mass spectrometry analysis. Volatilization of particles collected on the Teflon filter varied from 15 to 85% for both n -alkanes and PAHs, with strong dependence on molecular weight. The relative distribution of n -alkanes and the values of molecular diagnostic ratios, such as Carbon preference index, indicated a mixed origin with strong anthropogenic input. Indeed, CPI values ranged from 0.66 to 1.96 (for the whole range of n -alkanes). The percent contribution of leaf “wax” n -alkanes (4.55–20.83%) indicated the low contribution of biogenic sources. In addition, the distribution pattern of PAHs was characteristic of anthropogenic emissions. The dominant contribution of combustion-related PAHs (CPAHs), 74–84%, indicated that vehicular emissions was the major source of PAHs.

Formation and gas/particle partitioning of monoterpenes photo‐oxidation products over forests

By using adequate sampling techniques we studied the chemical pathways, the gas-to-particle partition and the conversion processes leading to the formation of organic aerosols via the photo-oxidation of biogenic hydrocarbons in the atmosphere over a conifer forest. Photo-oxidation products of monoterpenes such as pinonic acid, nor-pinonic acid, pinic acid, pinonaldehyde and nopinone were detected in the gas and particulate phases of all forest aerosol samples. Considering the diurnal concentration pattern of the photo-oxidation products of α- and β-pinene and Aitken nuclei concentration measured during the same periods, we observed that the acidic photo-oxidation products of monoterpenes play a more important role in the formation of new particles than the corresponding carbonyl compounds.

Source apportionment of PM10 and PM2.5 in five Chilean cities using factor analysis.

ABSTRACT Chile is a fast-growing country with important industrial activities near urban areas. In this study, the mass and elemental concentrations of PM10 and PM2.5 were measured in five major Chilean urban areas. Samples of particles with diameter less than 10 um (PM10) and 2.5 um (PM2.5) were collected in 1998 in Iquique (northern Chile), Valparaiso, Vina del Mar, Rancagua (central Chile), and Temuco (southern Chile). Both PM10 and PM25 annual mean concentrations (PM10: 56.9-77.6 u,g/m3; PM25: 22.4-42.6 u.g/m3) were significantly higher than the corresponding European Union (EU) and U.S. Environmental Protection Agency (EPA) air quality standards. Moreover, the 24-hr PM10 and PM25 U.S. standards were exceeded infrequently for some of the cities (Rancagua and Valparaiso).

The composition and sources of PM2.5 organic aerosol in two urban areas of Chile

Fine particle (PM2.5) samples were collected, using a charcoal diffusion denuder, in two urban areas of Chile, Santiago and Temuco, during the winter and spring season of 1998.Molecular markers of the organic aerosol were determined using GC/MS.Diagnostic ratios and molecular tracers were used to investigate the origin of carbonaceous aerosols.As main sources, road and non-road engine emissions in Santiago, and wood burning in Temuco were identified.Cluster analysis was used to compare the chemical characteristics of carbonaceous aerosols between the two urban environments.Distinct differences between Santiago and Temuco samples were observed.High concentrations of isoprenoid (30–69 ng m � 3 ) and unresolved complex mixture (UCM) of hydrocarbons (839–1369 ng m � 3 ) were found in Santiago.High concentrations of polynuclear aromatic hydrocarbons (751 7304 ng m � 3 ) and their oxygenated derivatives (47 2n g m � 3 ), and of n-alk-1-enes (16713 ng m � 3 ) were observed in Temuco. r 2002 Elsevier Science Ltd.

Development of a High Volume Cascade Impactor for Toxicological and Chemical Characterization Studies

This paper presents the design and development of a compact high volume cascade impactor (HVCI). The HVCI operates at a flow rate of 900 l/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup filter. The backup filter is placed downstream of the fourth stage and is used to collect the ultrafine particles ( d p < 0.1 w m). The major feature of this novel sampler is its ability to collect relatively large amounts of particles (mg-g levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected particles per cm 2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral oil, particle bounce and re-entrainment losses were found not to be significant. Particles can be easily recovered from the foam substrates using aqueous extraction. The impactor was calibrated using polydisperse particles. The 50% cutpoints of the 4 stages were 9.90, 2.46, 1.0, and 0.1 w m, respectively. Interstage losses of ultrafine and fine particles were < 10% and for coarse particles were < 20%. The pressure drop across the 4 stages and the backup filter were 0.25, 0.75, 1.25, 19.9, and 3.3 kPa, respectively.

Development and laboratory performance evaluation of a personal multipollutant sampler for simultaneous measurements of particulate and gaseous pollutants

A personal multipollutant sampler has been developed. This sampler can be used for measuring exposures to particulate matter and criteria gases. The system uses asingle personalsampling pump that operates at a flow rate of 5.2 l/min. The basic unit consists of two impaction-based samplers for PM2.5 and PM10 attached to a single elutriator. Two mini PM2.5 samplers are also attached to the elutriator for organic carbon (OC), elemental carbon (EC), sulfate, and nitrate measurements. For the collection of nitrate and sulfate, the minisampler includes a miniaturized honeycomb glass denuder that is placed upstream of the filter to remove nitric acid and sulfur dioxide and to minimize artifacts. Two passive samplers can also be attached to the elutriator for measurements of gaseous copollutants such as O3, SO2, and NO2. The performance of the multipollutant sampler was examined through a series of laboratory chamber tests. The results showed a good agreement between the multipollutant sampler and the reference methods. The overall sampler performance demonstrates its suitability for personal exposure assessment studies.

Lung function and indicators of exposure to indoor and outdoor particulate matter among asthma and COPD patients

Objectives: Misclassification of exposure related to the use of central sites may be larger for ultrafine particles than for particulate matter ⩽2.5 μm and ⩽10 μm (PM2.5 and PM10) and may result in underestimation of health effects. This paper describes the relative strength of the association between outdoor and indoor exposure to ultrafine particles, PM2.5 and PM10 and lung function. Methods: In four European cities (Helsinki, Athens, Amsterdam and Birmingham), lung function (forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and peak expiratory flow (PEF)) was measured three times a day for 1 week in 135 patients with asthma or chronic obstructive pulmonary disease (COPD), covering study periods of >1 year. Daily concentrations of particle number, PM2.5 and PM10 were measured at a central site in each city and both inside and outside the subjects’ homes. Results: Daily average particle number concentrations ranged between 2100 and 66 100 particles/cm3. We found no association between 24 h average particle number or particle mass concentrations and FVC, FEV1 and PEF. Substituting home outdoor or home indoor concentrations of particulate air pollution instead of the central site measurements did not change the observed associations. Analyses restricted to asthmatics also showed no associations. Conclusions: No consistent associations between lung function and 24 h average particle number or particle mass concentrations were found in panels of patients with mild to moderate COPD or asthma. More detailed exposure assessment did not change the observed associations. The lack of association could be due to the high prevalence of medication use, limited ability to assess lagged effects over several days or absence of an effect.

Dependence of home outdoor particulate mass and number concentrations on residential and traffic features in urban areas

Abstract The associations between residential outdoor and ambient particle mass, fine particle absorbance, particle number (PN) concentrations, and residential and traffic determinants were investigated in four European urban areas (Helsinki, Athens, Amsterdam, and Birmingham). A total of 152 nonsmoking participants with respiratory diseases, not exposed to occupational pollution, were included in the study, which comprised a 7-day intensive exposure monitoring period of both indoor and home outdoor particle mass and number concentrations. The same pollutants were also continuously measured at ambient fixed sites centrally located to the studied areas (fixed ambient sites). Relationships between concentrations measured directly outside the homes (residential outdoor) and at the fixed ambient sites were pollutant-specific, with substantial variations among the urban areas. Differences were more pronounced for coarse particles due to resuspension of road dust and PN, which is strongly related to traffic emissions. Less significant outdoor-to-fixed variation for particle mass was observed for Amsterdam and Birmingham, predominantly due to regional secondary aerosol. On the contrary, a strong spatial variation was observed for Athens and to a lesser extent for Helsinki. This was attributed to the overwhelming and time-varied inputs from traffic and other local sources. The location of the residence and traffic volume and distance to street and traffic light were important determinants of residential outdoor particle concentrations. On average, particle mass levels in suburban areas were less than 30% of those measured for residences located in the city center. Residences located less than 10 m from a street experienced 133% higher PN concentrations than residences located further away. Overall, the findings of this multi-city study, indicated that (1) spatial variation was larger for PN than for fine particulate matter (PM) mass and varied between the cities, (2) vehicular emissions in the residential street and location in the center of the city were significant predictors of spatial variation, and (3) the impact of traffic and location in the city was much larger for PN than for fine particle mass.

Air pollution and hospital emergency room and admissions for cardiovascular and respiratory diseases in Doña Ana County, New Mexico.

INTRODUCTION Doña Ana County in New Mexico regularly experiences severe air pollution episodes associated with windblown dust and fires. Residents of Hispanic/Latino origin constitute the largest population group in the region. We investigated the associations of ambient particulate matter and ozone with hospital emergency room and admissions for respiratory and cardiovascular visits in adults. METHODS We used trajectories regression analysis to determine the local and regional components of particle mass and ozone. We applied Poisson generalized models to analyze hospital emergency room visits and admissions adjusted for pollutant levels, humidity, temperature and temporal and seasonal effects. RESULTS We found that the sources within 500km of the study area accounted for most of particle mass and ozone concentrations. Sources in Southeast Texas, Baja California and Southwest US were the most important regional contributors. Increases of cardiovascular emergency room visits were estimated for PM10 (3.1% (95% CI: -0.5 to 6.8)) and PM10-2.5 (2.8% (95% CI: -0.2 to 5.9)) for all adults during the warm period (April-September). When high PM10 (>150μg/m(3)) mass concentrations were excluded, strong effects for respiratory emergency room visits for both PM10 (3.2% (95% CI: 0.5-6.0)) and PM2.5 (5.2% (95% CI: -0.5 to 11.3)) were computed. CONCLUSIONS Our analysis indicated effects of PM10, PM2.5 and O3 on emergency room visits during the April-September period in a region impacted by windblown dust and wildfires.