Polycyclic aromatic hydrocarbons and their oxygenated derivatives in urban aerosol: levels, chemical profiles, and contribution to PM2.5 oxidative potential.

The concentrations of polycyclic aromatic hydrocarbons (PAHs) and quinones, a subgroup of oxygenated PAHs (oxy-PAHs), were measured in PM2.5 samples collected during warm (May-June 2019) and cold (February-March 2020) seasons in the city of Bologna, Italy. Total PAHs concentration was nearly double in winter (6.58 ± 1.03 ng m-3) compared with spring (3.16 ± 0.53 ng m-3), following the trend of the PM2.5 mass concentration. Molecular diagnostic ratios suggested that, together with traffic, biomass burning was the dominant emission source contributing to the peaks of concentration of PM2.5 registered in the cold season. Quinone level was constant in both seasons, being 1.44 ± 0.24 ng m-3, that may be related to the increased secondary formation during warm season, as confirmed by the higher Σoxy-PAHs/ΣPAHs ratio in spring than in winter. The oxidative potential (OP) of the PM2.5 samples was assessed using acellular dithiothreitol (DTT) and ascorbic acid (AA) assays. The obtained responses showed a strong seasonality, with higher volume-normalized (OPV) values in winter than in spring, i.e., OPVDTT: 0.32 ± 0.15 nmol min-1 m-3 vs. 0.08 ± 0.03 nmol min-1 m-3 and OPVAA: 0.72 ± 0.36 nmol min-1 m-3 vs. 0.28 ± 0.21 nmol min-1 m-3. Both OPVDTT and OPVAA responses were significantly associated with total PAHs, as a general descriptor of redox-active PAH derivatives, associated with co-emission from burning sources or secondary atmospheric oxidation of parent PAHs. Otherwise, only winter OPVDTT responses showed a significant correlation with total Æ©oxy-PAHs concentration.

Understanding the environmental factors related to the decrease in Pediatric Emergency Department referrals for acute asthma during the SARS-CoV-2 pandemic.

BACKGROUND: Lockdown measures during the SARS-CoV-2 pandemic determined radical changes to behavioral and social habits, that were reflected by a reduction in the transmission of respiratory pathogens and in anthropogenic atmospheric emissions. OBJECTIVE: This ecological study aims to provide a descriptive evaluation on how restrictive measures during the SARS-CoV-2 pandemic impacted Pediatric Emergency Department (PED) referrals for asthma exacerbations, and their potentially associated environmental triggers in Bologna, a densely populated urban area in Northern Italy. METHODS: Files of children evaluated for acute asthma during 2015 to 2020 at the PED of Sant'Orsola University Hospital of Bologna were retrospectively reviewed. Historical daily concentration records of particulate (PM2.5 , PM10 ) and gaseous (NO2 , C6 H6 ) air pollutants, and pollen were concurrently evaluated, including specific PM chemical tracers for traffic-related air pollution (TRAP). RESULTS: In 2020, asthma-related PED referrals decreased compared to referral rates of the previous 5 years (p < 0.01). This effect was particularly marked during the first lockdown period (March to May), when the drastic drop in PED referrals was associated with a reduction of high-priority cases up to 85% and by 54%, on average. A concomitant reduction in the concentrations of traffic-related air pollutants was observed in the range of 40%-60% (p < 0.01). CONCLUSIONS: The lower rate of asthma exacerbations in childhood was in this study paralleled with reduced TRAP levels during the pandemic. Synergic interactions of the multiple consequences of lockdowns likely contributed to the reduced exacerbations, including decreased exposure to ambient pollutants and fewer respiratory infections, identified as the most important factor in the literature.

Source-related components of fine particulate matter and risk of adverse birth outcomes in Northern Italy.

BACKGROUND/AIM: The aim of the present study was to assess the association between PM2.5, its sources, and preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA) in a large open residential cohort (Supersito Project in the Emilia-Romagna Region - Northern Italy). METHODS: We collected 2012-2014 pregnancy and childbirth data from Birth Assistance Certificates and selected the pregnancies of interest. PTBs (gestational age < 37 weeks), LBW (weight < 2500 g), and SGA (newborns weighing ≤ 10th age and pregnancy week-specific percentile) were considered. Three-year measurements of daily concentrations and constituents of PM2.5 were available at four sites and were analyzed through a source apportionment approach identifying 6 sources (traffic, biomass burning, oil combustion, anthropogenic mix, and two secondary factors). Exposure to PM2.5 and sources was calculated at address level. Using logistic regression models, associations between exposure and outcomes were derived, applying single-pollutant and two-pollutant models, to verify the independent effect of each source. RESULTS: The study included 23,708 neonates born to 23,415 women, among whom 1,311 PTB, 424 LBW, and 1,354 SGA occurred. PTB was the only outcome associated with PM2.5 mass (OR 1.03, 95% CI 1.002-1.058 per 1 µg/m3). Traffic, oil combustion and secondary sulfates and organics showed independent effects on PTB. Exposure to secondary nitrates was associated with a lower risk of PTB. There was no association between LBW or SGA and source-specific PM2.5 components or the residual PM2.5 related to all other sources. CONCLUSION: This study found an association between PTB and PM2.5. Traffic, secondary sulfates, and organic and oil combustion were the sources with most consistent association.

Higher health effects of ambient particles during the warm season: The role of infiltration factors.

A large number of studies have shown much higher health effects of particulate matter (PM) during the warm compared to the cold season. In this paper we present the results of an experimental study carried out in an unoccupied test apartment with the aim of understanding the reasons behind the seasonal variations of the health effects due to ambient PM2.5 exposure. Measurements included indoor and outdoor PM2.5 mass and chemical composition as well as particle size distribution of ultrafine particles. Monitoring campaigns were carried out during summer and winter following a ventilation protocol developed to replicate typical occupant behaviour according to a questionnaire-based survey. Our findings showed that seasonal variation of the relationship between ambient and indoor mass concentrations cannot entirely explain the apparent difference in PM toxicity between seasons and size distribution and chemical composition of particles were identified as other possible causes of changes in the apparent PM toxicity. A marked decrease of ultrafine particles (<100 nm) passing from outdoors to indoors was observed during winter; this resulted in higher indoor exposure to nanoparticles (<50 nm) during summer. With regards to the chemical composition, a pooled analysis showed infiltration factors of chemical species similar to that obtained for PM2.5 mass with values increasing from 0.73 during winter to 0.90 during summer and few deviations from the pooled estimates. In particular, significantly lower infiltration factors and sink effect were found for nitrates and ammonium during winter. In addition, a marked increase in the contribution of indoor and outdoor sulfates to the total mass was observed during summer.

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.

Is particulate air pollution at the front door a good proxy of residential exposure?

The most advanced epidemiological studies on health effects of air pollution assign exposure to individuals based on residential outdoor concentrations of air pollutants measured or estimated at the front-door. In order to assess to what extent this approach could cause misclassification, indoor measurements were carried out in unoccupied rooms at the front and back of a building which fronted onto a major urban road. Simultaneous measurements were also carried out at adjacent outdoor locations to the front and rear of the building. Two 15-day monitoring campaigns were conducted in the period June-December 2013 in a building located in the urban area of Bologna, Italy. Particulate matter metrics including PM2.5 mass and chemical composition, particle number concentration and size distribution were measured. Both outdoor and indoor concentrations at the front of the building substantially exceeded those at the rear. The highest front/back ratio was found for ultrafine particles with outdoor concentration at the front door 3.4 times higher than at the rear. A weak influence on front/back ratios was found for wind direction. Particle size distribution showed a substantial loss of particles within the sub-50 nm size range between the front and rear of the building and a further loss of this size range in the indoor data. The chemical speciation data showed relevant reductions for most constituents between the front and the rear, especially for traffic related elements such as Elemental Carbon, Iron, Manganese and Tin. The main conclusion of the study is that gradients in concentrations between the front and rear, both outside and inside the building, are relevant and comparable to those measured between buildings located in high and low traffic areas. These findings show high potential for misclassification in the epidemiological studies that assign exposure based on particle concentrations estimated or measured at subjects' home addresses.

Characteristics and major sources of carbonaceous aerosols in PM2.5 in Emilia Romagna Region (Northern Italy) from four-year observations.

The concentrations of organic and elemental carbon in PM2.5 aerosol samples were measured in two sites of Emilia Romagna (Po Valley, Northern Italy) in eight campaigns during different seasons from 2011 to 2014. Strong seasonality was observed with the highest OC concentrations during the cold periods (≈ 5.5 µg m(-3)) and the lowest in the warm months (≈ 2.7 µg m(-3)) as well as with higher EC levels in fall/winter (≈ 1.4 µg m(-3)) in comparison with spring/summer (≈ 0.6 µg m(-3)). Concerning spatial variability, there were no statistically significant difference (p<0.05) between OC concentrations at the two sampling sites in each campaign, while the EC values were nearly twofold higher levels at the urban site than those at the rural one. Specific molecular markers were investigated to attempt the basic apportionment of OC by discriminating between the main emission sources of primary OC, such as fossil fuels burning - including traffic vehicle emission - residential wood burning, and bio-aerosol released from plants and microorganisms, and the atmospheric photo-oxidation processes generating OCsec. The investigated markers were low-molecular-weight carboxylic acids - to describe the contribution of secondary organic aerosol - anhydrosugars - to quantify primary emissions from biomass burning - bio-sugars - to qualitatively estimate biogenic sources - and Polycyclic Aromatic Hydrocarbons - to differentiate among different combustion emissions. Using the levoglucosan tracer method, contribution of wood smoke to atmospheric OC concentration was computed. Wood burning accounts for 33% of OC in fall/winter and for 3% in spring/summer. A clear seasonal trend is also observed for the impact of secondary processes with higher contribution in the warm seasons (≈ 63%) in comparison with that in colder months (≈ 33%), that is consistent with enhanced solar radiation in spring/summer.

Ultrafine particle concentrations in the surroundings of an urban area: comparing downwind to upwind conditions using Generalized Additive Models (GAMs).

The aim of this study was to investigate the influence of an urban area on ultrafine particle (UFP) concentration in nearby surrounding areas. We assessed how downwind and upwind conditions affect the UFP concentration at a site placed a few kilometres from the city border. Secondarily, we investigated the relationship among other meteorological factors, temporal variables and UFP. Data were collected for 44 days during 2008 and 2009 at a rural site placed about 3 kilometres from Bologna, in northern Italy. Measurements were performed using a spectrometer (FMPS TSI 3091). The average UFP number concentration was 11 776 (±7836) particles per cm(3). We analysed the effect of wind direction in a multivariate Generalized Additive Model (GAM) adjusted for the principal meteorological parameters and temporal trends. An increase of about 25% in UFP levels was observed when the site was downwind of the urban area, compared with the levels observed when wind blew from rural areas. The size distribution of particles was also affected by the wind direction, showing higher concentration of small size particles when the wind blew from the urban area. The GAM showed a good fit to the data (R(2) = 0.81). Model choice was via Akaike Information Criteria (AIC). The analysis also revealed that an approach based on meteorological data plus temporal trends improved the goodness of the fit of the model. In addition, the findings contribute to evidence on effects of exposure to ultrafine particles on a population living in city surroundings.

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.

Bioclimatic characterisation of an urban area: a case study in Bologna (Italy).

Summer bioclimatic discomfort is a significant public health problem. Bioclimatic characterisations of populations living in urban areas are usually very poor, although the risks are relatively higher in cities because of the phenomenon known as the "urban heat island". We compared airport, rural, and urban bioclimatic conditions in terms of apparent temperature, Thom index, and temperature alone in several sites within a radius of approximately 25 km from the city of Bologna (Italy). The comparison between meteorological monitoring stations within and near the urban area showed the large impact of the urban heat island effect. Nighttime data showed the largest differences among the investigated sites. Minimum apparent temperatures at rural stations were about 3.5 degrees C lower than the urban 30 m reference station, and 6 degrees C lower than the 2 m urban site. The 2 m apparent temperature values within the urban area were several degrees higher (typically 2 degrees C) than those taken above the roof, both for minimum and maximum values. Temporal trends in the different sites were highly correlated (generally above 0.90), but regression residuals were sometimes quite large. Finally, epidemiological implications are briefly addressed.

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.

Urban air pollution monitoring and correlation properties between fixed-site stations.

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.