Few European studies have investigated the effects of long-term exposure to both fine particulate matter (≤ 2.5 µm; PM2.5) and nitrogen dioxide (NO2) on mortality.
We studied the association of ...exposure to NO2, PM2.5, and traffic indicators on cause-specific mortality to evaluate the form of the concentration-response relationship.
We analyzed a population-based cohort enrolled at the 2001 Italian census with 9 years of follow-up. We selected all 1,265,058 subjects ≥ 30 years of age who had been living in Rome for at least 5 years at baseline. Residential exposures included annual NO2 (from a land use regression model) and annual PM2.5 (from a Eulerian dispersion model), as well as distance to roads with > 10,000 vehicles/day and traffic intensity. We used Cox regression models to estimate associations with cause-specific mortality adjusted for individual (sex, age, place of birth, residential history, marital status, education, occupation) and area (socioeconomic status, clustering) characteristics.
Long-term exposures to both NO2 and PM2.5 were associated with an increase in nonaccidental mortality hazard ratio (HR) = 1.03 (95% CI: 1.02, 1.03) per 10-µg/m3 NO2; HR = 1.04 (95% CI: 1.03, 1.05) per 10-µg/m3 PM2.5. The strongest association was found for ischemic heart diseases (IHD) HR = 1.10 (95% CI: 1.06, 1.13) per 10-µg/m3 PM2.5, followed by cardiovascular diseases and lung cancer. The only association showing some deviation from linearity was that between NO2 and IHD. In a bi-pollutant model, the estimated effect of NO2 on mortality was independent of PM2.5.
This large study strongly supports an effect of long-term exposure to NO2 and PM2.5 on mortality, especially from cardiovascular causes. The results are relevant for the next European policy decisions regarding air quality.
Flux–profile relationships are crucial for parametrizing surface fluxes of momentum and heat, that are of central relevance for applications such as climate modelling and weather forecast. ...Nevertheless, their functional forms are still under discussion, and a generally accepted formulation does not exist yet. We reviewed the four main formulations proposed in the literature so far and assessed how they affect the theoretical behaviour of the kinematic heat flux (H0) and the temperature scale (T*) in the stable boundary layer, as well as their consequences on the existence of critical values for both the gradient and the flux Richardson numbers. None of them turned out to be fully consistent with the literature published so far, with two of them leading to very unreliable expressions for both H0 and T*. All considered, a convincing description of flux–profile relationships still needs to be found and seems to represents a considerable challenge.
For environmental odor nuisance, it is extremely important to identify the instantaneous concentration statistics. In this work, a Fluctuating Plume Model for different statistical moments is ...proposed. It provides data in terms of mean concentrations, variance, and intensity of concentration. The 90th percentile peak-to-mean factor, R90, was tested here by comparing it with the experimental results (Uttenweiler field experiment), considering different Probability Distribution Functions (PDFs): Gamma and the Modified Weibull. Seventy-two percent of the simulated mean concentration values fell within a factor 2 compared to the experimental ones: the model was judged acceptable. Both the modelled results for standard deviation, σC, and concentration intensity, Ic, overestimate the experimental data. This evidence can be due to the non-ideality of the measurement system. The propagation of those errors to the estimation of R90 is complex, but the ranges covered are quite repeatable: the obtained values are 1–3 for the Gamma, 1.5–4 for Modified Weibull PDF, and experimental ones from 1.4 to 3.6.
In general, odours are perceived by humans through a single respiratory act having a duration of approximately 5 seconds. Moreover, odour concentration varies almost randomly over time, as any other ...physical variable in a turbulent environment. For this reason, both field measurements and dispersion models used for odour impact assessment purposes should be able to refer to short sampling times, instead of considering concentrations averaged over prolonged periods (i.e. 1 hour). This paper has the aim to investigate the problem of odour concentration fluctuations and their correlation with odour nuisance, thereby briefly discussing the problem of turbulence based on some theoretical considerations and of a few experimental results. The experimental results relevant to the continuous monitoring of instantaneous H2S concentration in ambient air clearly show that peak concentration exceed 1-hour average concentrations by almost 1 order of magnitude. Finally, the paper discusses the possible implementation of a dispersion model specifically dedicated to odour nuisance evaluation, thereby investigating different solutions to account for concentration fluctuations. The investigation related to the peak-to-mean approach, currently being the most widely used method to evaluate peak concentrations from 1-hour averaged concentrations on a regulatory level, allowed to point out the drawbacks of this methodology, which, despite its simplicity and ease-of-use, is unable to accurately describe the concentration fluctuations phenomena.
The characteristics of the vertical and temporal structure of the coastal atmospheric boundary layer are variable for different sites and are often not well known. Continuous monitoring of the ...atmospheric boundary layer was carried out close to the Tyrrhenian Sea, near Tarquinia (Italy), in 2015–2017. A ground-based remote sensing instrument (triaxial Doppler sodar) and in situ sensors (meteorological station, ultrasonic anemometer/thermometer, and net radiometer) were used to measure vertical wind velocity profiles, the thermal structure of the atmosphere, the height of the turbulent layer, turbulent heat and momentum fluxes in the surface layer, atmospheric radiation, and precipitation. Diurnal alternation of the atmospheric stability types governed by the solar cycle coupled with local sea/land breeze circulation processes is found to be variable and is classified into several main regimes. Low-level jets (LLJ) at heights of 100–300 m above the surface with maximum wind speed in the range of 5–18 m s−1 occur in land breezes, both during the night and early in the morning. Empirical relationships between the LLJ core wind speed characteristics and those near the surface are obtained. Two separated turbulent sub-layers, both below and above the LLJ core, are often observed, with the upper layer extending up to 400–600 m. Kelvin–Helmholtz billows associated with internal gravity–shear waves occurring in these layers present opposite slopes, in correspondence with the sign of vertical wind speed gradients. Our observational results provide a basis for the further development of theoretical and modelling approaches, taking into account the wave processes occurring in the atmospheric boundary layer at the land–sea interface.
Numerical weather prediction models require an accurate parametrization of the energy budget at the air-ground interface, that can be obtained only through long-term atmospheric boundary layer ...measurements at different spatial and temporal scales. Despite their importance, such measurements are still scarce even in well-characterized areas. In this paper, a three-year dataset from four micrometeorological stations run by the Regional Agency for Environmental Protection of Lazio was analyzed to estimate albedo, zero-displacement height, roughness length and surface properties over Rome and its suburbs, characterizing differences and interconnections between urban, suburban and rural areas of the same municipality. The integral albedo coefficient at the zenith for the urban station was found to be almost twice that for suburban and rural stations. The zero-displacement height of the urban site was strongly dependent on wind direction, with values varying between 12.0 and 17.8 m, while the roughness length (≈1.5 m) was almost independent of upwind direction, but it was significantly higher than the typical values calculated for rural stations (≈0.4 m). The apparent thermal capacities and thermal conductivity at all the non-urban sites were in fair agreement with each other and typical of soils with relatively low water content, as expected for a relatively dry Mediterranean area like Rome, while the apparent thermal diffusivity reflected the presence of different soil types.
Background and aimsResidents near industrial areas are exposed to several toxins from various sources and the assessment of the health effects is difficult. The area of Civitavecchia (Italy) has ...several sources of environmental contamination with potential health effects. We evaluated the association between exposure to pollutants from multiple sources and mortality in a cohort of people living in the area.MethodsAll residents of the area in 1996 were enrolled (from municipal registers) and followed until 2013. Long-term exposures to emissions from industrial sources (PM10) and traffic (NOx) at the residential addresses were assessed using a dispersion model. Residence close to the harbour was also considered. Cox survival analysis was conducted including a linear term for industrial PM10 and NOx exposure and a dichotomous variable to indicate residence within 500 m of the harbour. Age, sex, calendar period, occupation and area-based socioeconomic position (SEP) were considered (HRs, 95% CI).Results71 362 people were enrolled (52% female, 43% low SEP) and 14 844 died during the follow-up. We found an association between industrial PM10 and mortality from non-accidental causes (HR=1.06, 95% CI 1.01 to 1.12), all cancers (HR=1.11, 95% CI 1.01 to 1.21) and cardiac diseases (HR=1.12, 95% CI 1.01 to 1.23). We also found an association between NOx exposure from traffic and mortality from all cancers (HR=1.13, 95% CI 1.01 to 1.26) and neurological diseases (HR=1.50, 95% CI 1.01 to 2.20). Living near the harbour was associated with higher mortality from lung cancer (HR=1.31, 95% CI 1.04 to 1.66) and neurological diseases (HR=1.51, 95% CI 1.05 to 2.18).ConclusionsEstimated exposures to different pollution sources in this area were independently associated with several mortality outcomes while adjusting for occupation and socioeconomic status.
Kelvin–Helmholtz billows (KHBs) within a rising turbulent layer during the transition period from stable to unstable stratification occurring in the morning hours in summertime at the interior of ...Antarctica (Dome C, Concordia station) are examined in this study. The wave pattern captured by high-resolution sodar echograms from November 2014–February 2015 exhibits regular braid-like structures, associated with Kelvin–Helmholtz shear instabilities. This phenomenon is observed in more than 70% of days in the selected period. Two main regimes of the morning evolution with KHBs are identified roughly, distinguished by the presence or absence of turbulence in the preceding night-time. The weather and turbulent conditions favouring the occurrence of these regimes are analyzed. Also, two distinct patterns of KHBs are identified: (i) quasi-periodical (with periods ≈ 8–15 min) trains containing 5–10 braids, (ii) about continuous series lasting 20–90 min containing 20–80 braids. A composite shape of KHBs is determined. The periodicity of these waves is estimated to be between 20 and 70 s, and their wavelength is estimated roughly to be 100–400 m. The vertical thickness of individual braids at the wave crests ranges between 5 and 25 m. The total depth of a rising turbulent layer containing these waves varies between 15 and 120 m, and the ratio of the wavelength to the depth of the wave layer varies from 3 to 12 with a mean value ≈ 8.2. The morphology of the turbulence structure in the ABL is studied as a function of both temperature and wind field characteristics retrieved from an instrumented 45-m tower and an ultrasonic anemometer-thermometer at 3.5 m. The observational results highlight the necessity of considering the interaction between convective and wave processes when occurring simultaneously.
In the frame of the modelling simulation of odour nuisances, the estimation of concentration peaks, representing values averaged over a relatively short time of the order of the interval between ...subsequent breathes, is of fundamental importance. Dispersion models currently used in this field cannot reconstruct this kind of values at relatively high frequency, due to their intrinsic theoretical design that allows to give time- or ensemble average- concentrations only. The scope of this work is to describe the implementation of a simplified micromixing model inside a standard ensemble average Lagrangian Particle Dispersion Model, with the aim of simulating the field of concentration variances together with concentration averages. A simplified micromixing model represents a way to describe the interaction between the part of the emitted plume and the rest of the atmospheric flow, derived through bulk entrainment relationships. This simplified view allows the description of the first two moments of the concentration distribution which is however sufficient to describe a peak-to-mean relationship making some hypotheses about the form of the distribution. Some preliminary results of the application of this method inside the SPRAY Lagrangian Particle Dispersion Model are shown, comparing both the instantaneous concentration and the peak-to-mean ratio together with their spatial behaviour derived in some controlled conditions with those obtained from the application of other schemes currently included in the code.
A landfill, an incinerator, and a refinery plant have been operating since the early 1960s in a contaminated site located in the suburb of Rome (Italy). To evaluate their potential health effects, a ...population-based retrospective cohort study was conducted using dispersion modeling for exposure assessment.
A fixed cohort was enrolled in the Rome Longitudinal Study in 2001, mortality and hospitalizations were followed-up until 2010. Exposure assessments to the landfill (H2S), the incinerator (PM10), and the refinery plant (SOX) were performed for each subject using a Lagrangian dispersion model. Individual and small-area variables were available (including exposures levels to NO2 from traffic and diesel trucks). Cox regression analysis was performed (hazard ratios, HRs, 95% CI) using linear terms for the exposures (5th–95th percentiles difference). Single and bi-pollutant models were run.
The cohort included 85,559 individuals. The estimated annual average exposures levels were correlated. H2S from the landfill was associated with cardiovascular hospital admissions in both genders (HR 1.04 95% CI 1.00–1.09 in women); PM10 from the incinerator was associated with pancreatic cancer mortality in both genders (HR 1.40 95% CI 1.03–1.90 in men, HR 1.47 95% CI 1.12–1.93 in women) and with breast morbidity in women (HR 1.13 95% CI 1.00–1.27). SOx from the refinery was associated with laryngeal cancer mortality in women (HR 4.99 95% CI 1.64–15.9) and respiratory hospital admissions (HR 1.13 95% CI 1.01–1.27).
We found an association of the pollution sources with some cancer forms and cardio-respiratory diseases. Although there was a high correlation between the estimated exposures, an indication of specific effects from the different sources emerged.
•A residential cohort approach in an Italian industrial contaminated site was conducted.•Health status of 85,559 residents nearby a municipal solid waste landfill, an incinerator and a refinery was studied.•Dispersion modeling technique for population exposure was carried out.•Pancreatic and laryngeal cancer and cardio-respiratory diseases were detected.
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