The bio-distribution,clearance pathways,and toxicity mechanisms of ambient ultrafine particles

Ambient particles severely threaten human health worldwide.Compared to larger particles,ultrafine particles(UFPs)are highly concentrated in ambient environments,have a larger specific surface area,and are retained for a longer time in the lung.Recent studies have found that they can be transported into various extra-pulmonary organs by crossing the air-blood barrier(ABB).Therefore,to understand the adverse effects of UFPs,it is crucial to thoroughly investigate their bio-distribution and clearance pathways in vivo after inhalation,as well as their toxicological mechanisms.This review highlights emerging evidence on the bio-distribution of UFPs in pulmonary and extra-pulmonary organs.It explores how UFPs penetrate the ABB,the blood-brain barrier(BBB),and the placental barrier(PB)and subsequently undergo clearance by the liver,kidney,or intestine.In addition,the potential underlying toxicological mechanisms of UFPs are summarized,providing fundamental insights into how UFPs induce adverse health effects.

Hygroscopicity of ambient submicron particles in urban Hangzhou,China

In this study,hygroscopicity of size-segregated ambient submicron particles in urban Hangzhou was studied from 28th December 2009 to 18th January 2010,using a hygroscopicity-tandem differential mobility analyzer(H-TDMA).The submicron particles in Hangzhou showed a minor hygroscopic growth at 73%relative humidity(RH),and then grew significantly between 77%and 82%RH.Monomodal distribution accounted for 90%for 30 nm particles,17%for 50 nm particles,and less than 7%for particles larger than 50 nm at 82%RH.Deconvolution of the bimodal distribution indicated a less hygroscopic group and a more hygroscopic group,with the fraction of the more hygroscopic group increasing with the initial dry particle size and then remaining almost constant for accumulation mode particles.Our results imply that submicron particles in urban Hangzhou were almost entirely externally mixed,and the hygroscopic properties of ambient particles in urban Hangzhou were mainly a function of their size and chemical composition.

Comprehensive characterization of ambient nanoparticles collected near an industrial science park:Particle size distributions and relationships with environmental factors

We investigated the characteristics of ambient particles and their relationships with various environmental factors, including gaseous pollutants （CI-h, non-methane hydrocarbons （NMHC）, total hydrocarbons （THC）, NOx, CO, SO2）, meteorological parameters （humidity, temperature）, and time （day/night, workday/weekend）. We used an electrical low-pressure cascade impactor to measure the number and size distributions of ambient particles （0.007-10 ~m） that were collected approximately 1 km northwest of Hsinchu Science Park in Taiwan between February and May 2007. The number concentrations of particles were enhanced through photochemical reactions during the day. In addition, high traffic flow during workdays increased the formation of particulates. Except for SO2, all of the gaseous pollutants we studied （CH4, NMHC, THC, NOx, CO） correlated positively with the total number concentrations of ambient particles during daytime, indicating that they might contribute to the particulate burden. The poorer relationship between the SO2 level and the total number concentration of particles suggests that SO2 might participate indirectly in the nucleation process during particle formation, The high enrichment factors for Zn, Pb, Cu, and Mn, which mostly comprised the ultrafine particles （diameter： 〈 0.1 Ixm） and fine particles （diameter： 0.1-1 ~tm）, presumably arose from emissions from traffic and high technology factories. Heterogeneous reactions on solid particles might play a role in the removal of SOx and NOx from the atmosphere. Sulfides and nitrides can further react with these local pollutants, forming specific Cu-containing compounds： Cut （39%）, CuSO4 （34%）, and Cu（NO3）2 （27%）, within the ambient particles in this industrial area.

The role of mitochondria in inflammatory syndromes

Several authors have addressed the importance of mitochondrial function in inflammatory syn-dromes,as it may play a role in the genesis of tissue injury.Sepsis and exposition to environmental particles are examples of inflammatory conditions.Sepsis occurs with an exacerbated inflammatory response that damages tissue mitochondria and impairs bioenergetic processes.One of the current hypotheses for the molecular mech-anisms underlying the complex condition of sepsis is that enhanced NO production and oxidative stress lead to mitochondrial dysfunction,bioenergetic derangement and organ failure.The mechanism of particulate mat-terhealth effects are believed to involve inflammation and oxidative stress.Components in particles that elicit inflammation have been poorly investigated,although recent research points out to the contribution of composi-tional elements and particle size.Oxygen metabolism and mitochondrial function appear to be important areas of study in inflammatory conditions for clarifying molecular mechanisms involved.

Seasonal size-segregated PM10 and PAH concentrations in a rural area of sugarcane agriculture versus a coastal urban area in Southeastern Florida, USA

Airborne particulate matter （PM） is of health and environmental concern not only in highly urbanized areas, but also in rural areas that are used for intensive agricultural purposes, In this study, PM size- segregated samples were collected simultaneously for 12 months in a small town （Belle Glade, Florida）, which is the center of a vast sugarcane growing area and at Delray Beach, a coastal city in Palm Beach County, Florida. During the winter sampling period, when sugarcane foliage is burned just before harvest- ing to reduce the amount of plant matter to be handled, PM10 levels were 50% or higher than otherwise measured, indicating that sugarcane harvesting and processing is a major local source for PM10. For the rest of the year, PM10 levels at both sites are similar, suggesting that ambient PM levels at both sites are impacted by the major urban centers in Southern Florida. During late July and early August, the PM10 levels at both sites were substantially elevated and revealed the typical red-brownish color of Saharan dust. This has been reported to occur frequently with suitable meteorological conditions over the Atlantic Ocean coupled with a Sahara dust storm event. During the sugarcane harvesting season at Belle Glade, the concentrations of PAHs associated with PM10 were up to 15 times higher than those measured during the summer growing season, indicating a substantially higher exposure of the rural population to these often mutagenic and carcinogenic compounds.