Stefano Zauli Sajani

Saharan dust and daily mortality in Emilia-Romagna (Italy)

Objective To investigate the association between Saharan dust outbreaks and natural, cardiovascular and respiratory mortality. Methods A case–crossover design was adopted to assess the effects of Saharan dust days (SDD) on mortality in the Emilia-Romagna region of Italy. The population under study consisted of residents in the six main towns of the central-western part of the region who died between August 2002 and December 2006. The association of Saharan dust outbreaks and PM10 concentration with mortality was estimated using conditional logistic regression, adjusted for apparent temperature, holidays, summer population decrease, flu epidemic weeks and heat wave days. The role of the interaction term between PM10 and SDD was analysed to test for effect modification induced by SDD on the PM10-mortality concentration–response function. Separate estimates were undertaken for hot and cold seasons. Results We found some evidence of increased respiratory mortality for people aged 75 or older on SDD. Respiratory mortality increased by 22.0% (95% CI 4.0% to 43.1%) on the SDD in the whole year model and by 33.9% (8.4% to 65.4%) in the hot season model. Effects substantially attenuated for natural and cardiovascular mortality with ORs of 1.042 (95% CI 0.992 to 1.095) and 1.043 (95% CI 0.969 to 1.122), respectively. Conclusions Our findings suggest an association between respiratory mortality in the elderly and Saharan dust outbreaks. We found no evidence of an effect modification of dust events on the concentration–response relationship between PM10 and daily deaths. Further work should be carried out to clarify the mechanism of action.

Emergency ambulance dispatches and apparent temperature: A time series analysis in Emilia-Romagna, Italy

INTRODUCTION Increases in mortality associated with oppressive weather have been widely investigated in several epidemiological studies. However, to properly understand the full public health significance of heat-related health effects, as well as to develop an effective surveillance system, it is also important to investigate the impact of stressful meteorological conditions on non-fatal events. The objective of our study was to evaluate the exposure-response relationship of ambulance dispatch data in association with biometeorological conditions using time series techniques similar to those used in previous studies on mortality. METHODS Daily data of emergency ambulance dispatches for people aged 35 or older in the summer periods from 2002 to 2006 were collected for the major towns in the Emilia-Romagna region. In the first stage of the analysis, the city-specific relationship between daily ambulance dispatches and increasing apparent temperature was explored using Generalized Additive Models while controlling for air pollution, seasonality, long-term trend, holidays and weekends. The relationship between ambulance dispatches and apparent temperature was approximated by linear splines. The effects of high temperatures on health were evaluated for respiratory and cardiovascular diseases as well as for all non-traumatic conditions. In the second stage of the analysis, city-specific effects were combined in fixed or random effect meta-analyses. RESULTS The percent change in the ambulance dispatches associated with every 1 °C increase in the mean apparent temperature between 25 and 30 °C was 1.45% (95% confidence interval: 0.95, 1.95) for non-traumatic diseases and 2.74% (95% CI: 1.34, 4.14) for respiratory diseases. The percent increase in risk was greater on days in which the mean apparent temperature exceeded 30 °C (8.85%, 95% CI: 7.12, 10.58 for non-traumatic diseases). In this interval of biometeorological conditions, cardiovascular diseases became positively associated with the apparent temperature. The risks increased with age. The increase in risk for the non-traumatic diseases reached 13.34% for people aged 75 or older compared to 4.75% for those aged 35-64. CONCLUSION Time series analysis techniques were adopted for the first time to investigate emergency ambulance dispatches to evaluate the risks associated with biometeorological discomfort. Our findings show a strong relationship between biometeorological conditions and ambulance dispatches.

Urban Air Pollution Monitoring and Correlation Properties between Fixed-Site Stations

Abstract The rich regional air-monitoring network of the Emilia-Romagna region of Italy has been used to quantify the spatial variability of the main pollutants within urban environments and to analyze the correlations between stations. The spatial variability of the concentrations of the majority of pollutants within the city was very high, making it difficult to differentiate and characterize the urban environments and to apply legal limits with uniform criteria. On the other hand, the correlations between the fixed-site monitoring stations were high enough for their data to be retained generally very appropriately for controlling temporal trends. Starting from the high correlation level, a procedure was proposed and tested to derive pollution levels, using short-term measurements, such as passive samplers and mobile-station data. The importance of long-term statistics in urban air pollution mapping was emphasized. Treatment of missing data in time series and quality assurance were indicated as possible fields for applications for the correlation properties.

Comparison of different exposure settings in a case--crossover study on air pollution and daily mortality: counterintuitive results.

Because of practical problems associated with measurement of personal exposures to air pollutants in larger populations, almost all epidemiological studies assign exposures based on fixed-site ambient air monitoring stations. In the presence of multiple monitoring stations at different locations, the selection of them may affect the observed epidemiological concentration–response (C-R) relationships. In this paper, we quantify these impacts in an observational ecologic case–crossover study of air pollution and mortality. The associations of daily concentrations of PM10, O3, and NO2 with daily all-cause non-violent mortality were investigated using conditional logistic regression to estimate percent increase in the risk of dying for an increase of 10 μg/m3 in the previous day air pollutant concentrations (lag 1). The study area covers the six main cities in the central-western part of Emilia-Romagna region (population of 1.1 million). We used four approaches to assign exposure to air pollutants for each individual considered in the study: nearest background station; city average of all stations available; average of all stations in a macro-area covering three cities and average of all six cities in the study area (50 × 150 km2). Odds ratios generally increased enlarging the spatial dimension of the exposure definition and were highest for six city-average exposure definition. The effect is especially evident for PM10, and similar for NO2, whereas for ozone, we did not find any change in the C-R estimates. Within a geographically homogeneous region, the spatial aggregation of monitoring station data leads to higher and more robust risk estimates for PM10 and NO2, even if monitor-to-monitor correlations showed a light decrease with distance. We suggest that the larger aggregation improves the representativity of the exposure estimates by decreasing exposure misclassification, which is more profound when using individual stations vs regional averages.

Are day-to-day variations of airborne particles associated with emergency ambulance dispatches?

Abstract Background: Much of the evidence on the health effects of airborne particles is based on mortality and hospital admissions, while the evidence from other morbidity indicators is still limited. Objective: To measure the relationship between particles with diameter below 10 μm (PM10) and emergency ambulance dispatches (EAD). Methods: Daily EAD for six towns of the Emilia-Romagna region (Italy) were obtained from a database collecting real-time data. Time series analyses were performed, and city-specific estimates were combined using meta-analytic techniques. Results: We found a significant percentage change of EAD associated with a 10 μg/m3 increase of PM10 for non-traumatic diseases (0·86%, 95%CI: 0·61,1·1%). A positive relationship was also found for cardiovascular and respiratory diseases without reaching statistical significance. The risks were much higher in the warm (April–September) than in the cold season (January–March and October–December). Conclusions: Emergency ambulance dispatches provide useful insight into the health effects of air pollution and may be useful to establish surveillance systems.

Only coarse particles from the Sahara

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Ambient temperature and FIT performance in the Emilia-Romagna colorectal cancer screening programme

Objective To assess the impact of ambient temperature on faecal immunochemical test (FIT) performance in the colorectal cancer screening programme of Emilia-Romagna (Italy). Methods A population-based retrospective cohort study on data from 2005 to 2011. Positive rate, detection rate, and positive predictive value rate for cancers and adenomas, and incidence rate of interval cancers after negative tests were analysed using Poisson regression models. In addition to ambient temperature, gender, age, screening history, and Local Health Unit were also considered. Results In 1,521,819 tests analysed, the probability of a positive result decreased linearly with increasing temperature. Point estimates and 95% Confidence Intervals were estimated for six temperature classes (<5, 5 |−10, 10 |−15, 15 |−20, 20|−25 and ≥25℃), and referred to the 5|-10℃ class. The positive rate ratio was significantly related to temperature increase: 0.99 (0.97–1.02), 1, 0.98 (0.96–1.00), 0.96 (0.94–0.99), 0.93 (0.91–0.96), 0.92 (0.89–0.95). A linear trend was also evident for advanced adenoma detection rate ratio: 1.00 (0.96–1.04), 1, 0.98 (0.93–1.02), 0.96 (0.92–1.00), 0.92 (0.88–0.96), 0.94 (0.88–1.01). The effect was less linear, but still important, for cancer detection rates: 0.95 (0.85–1.06), 1, 1.00 (0.90–1.10), 0.94 (0.85–1.05), 0.81 (0.72–0.92), 0.93 (0.80–1.09). No association or linear trend was found for positive predictive values or risk of interval cancer, despite an excess of +16% in the highest temperature class for interval cancer. Conclusions Ambient temperatures can affect screening performance. Continued monitoring is needed to verify the effect of introducing FIT tubes with a new buffer, which should guarantee a higher stability of haemoglobin.

A direct approach to control short term population dynamics in time series studies

Background: Short term population dynamics is an important issue in several epidemiological studies. Usually, calendar time or dummy variables are used to control indirectly for this confounding. This study tested a direct method. Methods: The study compared as proxy variables of population dynamics the summer 2003 data of cooking gas consumptions, solid urban waste production, and television access for the municipality of Bologna (Italy). Results: Solid urban waste production and television access data showed similar trends. Considerably different were the >65 year olds estimates with respect to total population based on television access. Conclusions: Television access data are probably the best indicator in the estimates of population dynamics in large or densely populated areas, especially because of the possibility of stratifications with respect to age.

Air quality assessment in Bologna by an urban dispersion model

An urban dispersion model (ADMS?Urban) was run to calculate PM10 and NO2 concentration during a one-year period, on a district of Bologna, Italy. Moreover, the exposure of 333 children was estimated using model outputs corrected with observations. The model was able to correctly simulate the long-term statistical properties of roadside observed concentrations (such as annual mean and frequency distribution), but it failed in reproducing instantaneous values. The proposed methodology is of easy implementation, and it could be useful to identify areas with high pollutant levels, to estimate population exposure and to evaluate the benefit of pollution reduction policies.

Vertical variation of PM2.5 mass and chemical composition, particle size distribution, NO2, and BTEX at a high rise building

Substantial efforts have been made in recent years to investigate the horizontal variability of air pollutants at regional and urban scales and epidemiological studies have taken advantage of resulting improvements in exposure assessment. On the contrary, only a few studies have investigated the vertical variability and their results are not consistent. In this study, a field experiment has been conducted to evaluate the variation of concentrations of different particle metrics and gaseous pollutants on the basis of floor height at a high rise building. Two 15-day monitoring campaigns were conducted in the urban area of Bologna, Northern Italy, one of the most polluted areas in Europe. Measurements sites were operated simultaneously at 2, 15, 26, 44 and 65 m a.g.l. Several particulate matter metrics including PM2.5 mass and chemical composition, particle number concentration and size distribution were measured. Time integrated measurement of NO2 and BTEX were also included in the monitoring campaigns. Measurements showed relevant vertical gradients for most traffic related pollutants. A monotonic gradient of PM2.5 was found with ground-to-top differences of 4% during the warm period and 11% during the cold period. Larger gradients were found for UFP (∼30% during both seasons) with a substantial loss of particles from ground to top in the sub-50 nm size range. The largest drops in concentrations for chemical components were found for Elemental Carbon (-27%), iron (-11%) and tin (-36%) during winter. The ground-to-top decline of concentrations for NO2 and benzene during winter was equal to 74% and 35%, respectively. In conclusion, our findings emphasize the need to include vertical variations of urban air pollutants when evaluating population exposure and associated health effects, especially in relation to some traffic related pollutants and particle metrics.