Dynamic of submicrometer particles in urban environment

Abstract

Many studies show that particle toxicity increases with decreasing their size, emphasizing the role of submicrometric particles, in particular of ultrafine particles (<100 nm). In fact, particles greater than 2.5 μm are quickly removed through dry and wet deposition on the timescale of hours whereas submicrometer particles may reside in atmosphere for weeks, penetrate in indoor environment, and be long-range transported. High aerosol size resolution measurements are important for a correct assessment of the deposition efficiency in the human respiratory system, and time resolution is another important requisite. Starting from such considerations, time-resolved aerosol particle number size distributions have been measured in downtown Rome. Fast Mobility Particle Sizer (FMPS) and Scanning Mobility Particle Sizer (SMPS) measurements have been carried out at the INAIL's Pilot Station, located in downtown Rome, in an area characterized by high density of autovehicular traffic. The two instruments have allowed to investigate deeply the urban aerosol in the range of 5.6-560 and 3.5-117 nm, respectively. In particular, the FMPS measurements have confirmed the interpretation about the transition phenomena in the time interval of few seconds, timescale typically associated with the emission of gasoline and diesel engines. In downtown Rome, the hourly average size distribution is bimodal or trimodal with maxima at about 5-15, 20-30, and 70-100 nm. Particle formation in the nucleation mode was associated to freshly emitted autovehicular exhaust.

Pedestrians in Traffic Environments: Ultrafine Particle Respiratory Doses

“…UFP percentage contribution was about 75% and confirms previous measurements, performed in a street canyon in downtown Rome, in which their percentage ranged between 70%–95% [49,50]; studies performed in other urban environments, in cities other than Rome, reported a percentage contribution of particles below 100 nm of about 80% of the total particle number concentration [51,52,53,54,55]. …”

Long-term exposure to ambient PM2.5 and impacts on health in Rome, Italy

“…Recent studies have reported adverse health effects of PM 2.5 exposure in Rome. 2,9,31,32,34 To better understand and quantify the health impacts of PM 2.5 on Rome City residents, the latest version of WHO recommended AirQ + modeling system (v3.0) was used in order to estimate the number of excess mortality cases of IHD, COPD, LC, stroke and WDL (morbidity) from long-term PM 2.5 exposure in Rome. In this study, ambient PM 2.5 concentrations were acquired from 1st January to 31 st December 2014 from 4 monitoring urban stations, representative of the background levels.…”

“…Recent epidemiological studies have demonstrated that ambient air pollutants, exacerbated by climate change, increase the risk of mortality and morbidity due to respiratory and cardiovascular diseases. [1][2][3][4][5][6] Air pollution is caused by several ambient harmful substances (e.g. SO 2 , NO 2 , O 3 , PM 10 ) but smaller aerosols with aerodynamic diameter lower than 2.5 μm (PM 2.5 ) are ubiquitous in most cities and are stringently regulated by European Commission (EC) since they are able to penetrate deeply into lungs alveoli, by inhalation, and cause important adverse effects on human health.…”

“…30 Rome is one of the European megacities with more than 3 million inhabitants; the city has experienced high PM 2.5 emissions over the years mostly due to high road traffic, biomass burning and industrial activities. 2,31 In Rome, PM 2.5 are emitted, in particular in early winter season, and are composed of carbonaceous matter, K and Na, characteristics of road traffic, heating and sea-salt. 32 The MED-PARTICLES project published results from a multi centric study involving 10 European cities.…”

Nanoparticle Behaviour in An Urban Street Canyon at Different Heights and Implications on Indoor Respiratory Doses

“…Aerosol measurementsOutdoor aerosol total number concentrations (CTot) over the 24 hours considered were on average 2.3-fold higher at ground floor than at 20 m heights with spike concentration ratios exceeding 20, up to about 40. Both sets of data shared the same temporal modulation with two broad peaks centered at 8 am and 7 pm, determined by the daily traffic flow variation and by the planetary boundary layer (PBL) mixing height that was highest in the central part of the day during period of high solar radiation(Figure 1)[39][40][41].…”