Size resolved aerosol respiratory doses in a Mediterranean urban area: From PM10 to ultrafine particles.

In the framework of the 2017 "carbonaceous aerosol in Rome and Environs" (CARE) experiment, particle number size distributions have been continuously measured on February 2017 in downtown Rome. These data have been used to estimate, through MPPD model, size and time resolved particle mass, surface area and number doses deposited into the respiratory system. Dosimetry estimates are presented for PM10, PM2.5, PM1 and Ultrafine Particles (UFPs), in relation to the aerosol sources peculiar to the Mediterranean basin and to the atmospheric conditions. Particular emphasis is focused on UFPs and their fraction deposited on the olfactory bulb, in view of their possible translocation to the brain. The site of PM10 deposition within the respiratory system considerably changes, depending on the aerosol sources and then on its different size distributions. On making associations between health endpoints and aerosol mass concentrations, the relevant coarse and fine fractions would be more properly adopted, because they have different sources, different capability of penetrating deep into the respiratory system and different toxicological implications. The separation between them should be set at 1 µm, rather than at 2.5 µm, because the fine fraction is considerably less affected by the contribution of the natural sources. Mass dose is a suitable metric to describe coarse aerosol events but gives a poor representation of combustion aerosol. This fraction of particles, made of UFPs and of accumulation mode particles (mainly with size below 0.2 µm), is of high health relevance. It elicited the highest oxidative activity in the CARE experiment and is properly described by the particle surface area and by the number metrics. Such metrics are even more relevant for the UFP doses deposited on the olfactory bulb, in consideration of the role recognized to oxidative stress in the progression of neurodegenerative diseases. Such metrics would be more appropriate, rather than PMx mass concentrations, to correlate neurodegenerative pathologies with aerosol pollution.

Impact of port emissions on EU-regulated and non-regulated air quality indicators: The case of Civitavecchia (Italy).

Current shipping activities employ about 3% of the world-delivered energy. Most of this energy is conveyed by diesel engines. In Europe, release of NOx and particulate matter (PM) from shipping is expected to equal the road-transport one by the year 2020. This paper addresses a typical central Mediterranean city-port condition to evaluate the relative contribution of shipping activities to the local air quality. A 3-year long air quality dataset collected at the boundary between the port of Civitavecchia (the major port in central Italy) and the city itself was analyzed to evaluate the long-term, relative contribution of the port and of the city at determining the loads of EU-regulated pollutants (NO2, PM10 and SO2). In addition, black carbon and ultrafine-to-coarse particles data collected along a short-term, intensive campaign were used to assess the port's role at emitting these unregulated pollutants. Cross-analysis of the measurements, allowed to assess which shipping-related activities and port's sectors represent the principal emitters. At the city-port boundary, the annual share of regulated pollutants originating in the port area by shipping and ground movements is of 33% for PM10, 43% for NO2, and 60% for SO2. Analysis of non-regulated pollutants shows the in-port, high polluting potential of some ship categories, in particular those employing low-sulfur but poorly refined oils. These conditions appear to be more often associated with Ro-Ro passenger ships. Piers closest to the Civitavecchia urban settlements are also observed to host the largest emissions. Meteorology and location of the piers with respect to residential areas are confirmed to govern the port's share at impacting the city air quality. Even though air quality thresholds for regulated pollutants are not exceeded in Civitavecchia, constant consideration of an enlarged set of environmental variables should drive actions implemented to mitigate the port's impact onto the nearby city's air quality.

Direct observation of aqueous secondary organic aerosol from biomass-burning emissions.

The mechanisms leading to the formation of secondary organic aerosol (SOA) are an important subject of ongoing research for both air quality and climate. Recent laboratory experiments suggest that reactions taking place in the atmospheric liquid phase represent a potentially significant source of SOA mass. Here, we report direct ambient observations of SOA mass formation from processing of biomass-burning emissions in the aqueous phase. Aqueous SOA (aqSOA) formation is observed both in fog water and in wet aerosol. The aqSOA from biomass burning contributes to the "brown" carbon (BrC) budget and exhibits light absorption wavelength dependence close to the upper bound of the values observed in laboratory experiments for fresh and processed biomass-burning emissions. We estimate that the aqSOA from residential wood combustion can account for up to 0.1-0.5 Tg of organic aerosol (OA) per y in Europe, equivalent to 4-20% of the total OA emissions. Our findings highlight the importance of aqSOA from anthropogenic emissions on air quality and climate.

[Air pollution in an urban area nearby the Rome-Ciampino city airport]. / Inquinamento atmosferico in un'area urbana limitrofa all'aeroporto di Roma-Ciampino.

OBJECTIVES: to assess air pollution spatial and temporal variability in the urban area nearby the Ciampino International Airport (Rome) and to investigate the airport-related emissions contribute. DESIGN AND SETTING: the study domain was a 64 km2 area around the airport. Two fifteen-day monitoring campaigns (late spring, winter) were carried out. Results were evaluated using several runs outputs of an airport-related sources Lagrangian particle model and a photochemical model (the Flexible Air quality Regional Model, FARM). MAIN OUTCOME MEASURES: both standard and high time resolution air pollutant concentrations measurements: CO, NO, NO2, C6H6, mass and number concentration of several PM fractions. 46 fixed points (spread over the study area) of NO2 and volatile organic compounds concentrations (fifteen days averages); deterministic models outputs. RESULTS: standard time resolution measurements, as well as model outputs, showed the airport contribution to air pollution levels being little compared to the main source in the area (i.e. vehicular traffic). However, using high time resolution measurements, peaks of particles associated with aircraft takeoff (total number concentration and soot mass concentration), and landing (coarse mass concentration) were observed, when the site measurement was downwind to the runway. CONCLUSIONS: the frequently observed transient spikes associated with aircraft movements could lead to a not negligible contribute to ultrafine, soot and coarse particles exposure of people living around the airport. Such contribute and its spatial and temporal variability should be investigated when assessing the airports air quality impact.

Saharan dust and the association between particulate matter and daily hospitalisations in Rome, Italy.

INTRODUCTION: Outbreaks of Saharan dust have been shown to exacerbate the effect of particulate matter (PM) on mortality. Their role on PM-morbidity association is less clear. This study aims to evaluate the effect of Saharan dust on the PM-hospitalisations association in Rome, Italy. METHODS: We studied residents hospitalised in Rome between 2001 and 2004 and performed a time-series analysis to explore the effects of PM2.5, PM2.5-10 and PM10 on cardiac, cerebrovascular and respiratory emergency hospitalisations, respectively. Saharan dust days were identified by combining Light Detection and Ranging observations and analyses from operational models. We tested a dust-PM interaction to evaluate the hypothesis that the PM effect on hospitalisations would be enhanced on dust days. RESULTS: We studied 77 354, 26 557 and 31 620 hospitalisations for cardiac, cerebrovascular and respiratory diseases, respectively, providing effect estimates per IQR. PM2.5-10 was associated with cardiac diseases (3.93%; 95% CI 1.58 to 6.34). PM10 was associated with cardiac (3.37%; 95% CI 1.11 to 5.68), cerebrovascular (2.64%; 95% CI 0.06 to 5.29) and respiratory diseases (3.59%: 95% CI 0.18 to 7.12). No effect of PM2.5 was detected. Saharan dust modified the effect of the PM2.5-10 on respiratory hospitalisations, higher during dust days compared with dust-free days (14.63% vs -0.32%; p value of interaction=0.006). Saharan dust also increased the effect of PM10 on cerebrovascular diseases (5.04% vs 0.90%, p value of interaction=0.143). DISCUSSION: A clear enhanced effect of PM2.5-10 on respiratory diseases and of PM10 on cerebrovascular diseases emerged during Saharan dust outbreaks.

Saharan dust and associations between particulate matter and daily mortality in Rome, Italy.

BACKGROUND: Outbreaks of Saharan-Sahel dust over Euro-Mediterranean areas frequently induce exceedances of the Europen Union's 24-hr standard of 50 µg/m3 for particulate matter (PM) with aerodynamic diameter ≤ than 10 µm (PM10). OBJECTIVES: We evaluated the effect of Saharan dust on the association between different PM fractions and daily mortality in Rome, Italy. METHODS: In a study of 80,423 adult residents who died in Rome between 2001 and 2004, we performed a time-series analysis to explore the effects of PM2.5, PM2.5-10, and PM10 on natural, cardiac, cerebrovascular, and respiratory mortality. We defined Saharan dust days by combining light detection and ranging (LIDAR) observations and analyses from operational models. We tested a Saharan dust-PM interaction term to evaluate the hypothesis that the effects of PM, especially coarse PM (PM2.5-10), on mortality would be enhanced on dust days. RESULTS: Interquartile range increases in PM2.5-10 (10.8 µg/m3) and PM10 (19.8 µg/m3) were associated with increased mortality due to natural, cardiac, cerebrovascular, and respiratory causes, with estimated effects ranging from 2.64% to 12.65% [95% confidence interval (CI), 1.18-25.42%] for the association between PM2.5-10 and respiratory mortality (0- to 5-day lag). Associations of PM2.5-10 with cardiac mortality were stronger on Saharan dust days (9.73%; 95% CI, 4.25-15.49%) than on dust-free days (0.86%; 95% CI, -2.47% to 4.31%; p = 0.005). Saharan dust days also modified associations between PM10 and cardiac mortality (9.55% increase; 95% CI, 3.81-15.61%; vs. dust-free days: 2.09%; 95% CI, -0.76% to 5.02%; p = 0.02). CONCLUSIONS: We found evidence of effects of PM2.5-10 and PM10 on natural and cause-specific mortality, with stronger estimated effects on cardiac mortality during Saharan dust outbreaks. Toxicological and biological effects of particles from desert sources need to be further investigated and taken into account in air quality standards.

Study of atmospheric aerosols and mixing layer by LIDAR.

The LIDAR (laser radar) is an active remote sensing technique, which allows for the altitude-resolved observation of several atmospheric constituents. A typical application is the measurement of the vertically resolved aerosol optical properties. By using aerosol particles as a marker, continuous determination of the mixing layer height (MLH) can also be obtained by LIDAR. Some examples of aerosol extinction coefficient profiles and MLH extracted from a 1-year LIDAR data set collected in Milan (Italy) are discussed and validated against in situ data (from a balloon-borne optical particle counter). Finally a comparison of the observation-based MLH with relevant numerical simulations (mesoscale model MM5) is provided.

Imaginary refractive-index effects on desert-aerosol extinction versus backscatter relationships at 351 nm: numerical computations and comparison with Raman lidar measurements.

A numerical model is used to investigate the dependence at 351 nm of desert-aerosol extinction and backscatter coefficients on particle imaginary refractive index (mi). Three ranges (-0.005 < or = mi < or = -0.001, -0.01 < or = mi < or = -0.001, and -0.02 < or = mi < or = -0.001) are considered, showing that backscatter coefficients are reduced as /mi/ increases, whereas extinction coefficients are weakly dependent on mi. Numerical results are compared with extinction and backscatter coefficients retrieved by elastic Raman lidar measurements performed during Saharan dust storms over the Mediterranean Sea. The comparison indicates that a range of -0.01 to -0.001 can be representative of Saharan dust aerosols and that the nonsphericity of mineral particles must be considered.