Size Distribution Of Atmospheric Particles Research Articles

Seasonal dynamics of airborne biomolecules influence the size distribution of Arctic aerosols

Organic matter is crucial in aerosol–climate interactions, yet the physicochemical properties and origins of organic aerosols remain poorly understood. Here we show the seasonal characteristics of submicron organic aerosols in Arctic Svalbard during spring and summer, emphasizing their connection to transport patterns and particle size distribution. Microbial-derived organic matter (MOM) and terrestrial-derived organic matter (TOM) accounted for over 90% of the total organic mass in Arctic aerosols during these seasons, comprising carbohydrate/protein-like and lignin/tannin-like compounds, respectively. In spring, aerosols showed high TOM and low MOM intensities due to biomass-burning influx in the central Arctic. In contrast, summer exhibited elevated MOM intensity, attributed to the shift in predominant atmospheric transport from the central Arctic to the biologically active Greenland Sea. MOM and TOM were associated with Aitken mode particles (<100 nm diameter) and accumulation mode particles (>100 nm diameter), respectively. This association is linked to the molecular size of biomolecules, impacting the number concentrations of corresponding aerosol classes. These findings highlight the importance of considering seasonal atmospheric transport patterns and organic source-dependent particle size distributions in assessing aerosol properties in the changing Arctic.

Concentration and size distribution of atmospheric particles in southern Italy during COVID-19 lockdown period

Many countries imposed lockdown (LD) to limit the spread of COVID-19, which led to a reduction in the emission of anthropogenic atmospheric pollutants. Several studies have investigated the effects of LD on air quality, mostly in urban settings and criteria pollutants. However, less information is available on background sites, and virtually no information is available on particle number size distribution (PNSD). This study investigated the effect of LD on air quality at an urban background site representing a near coast area in the central Mediterranean. The analysis focused on equivalent black carbon (eBC), particle mass concentrations in different size fractions: PM2.5 (aerodynamic diameter Da < 2.5 μm), PM10 (Da < 10 μm), PM10-2.5 (2.5 < Da < 10 μm); and PNSD in a wide range of diameters (0.01–10 μm). Measurements in 2020 during the national LD in Italy and period immediately after LD (POST-LD period) were compared with those in the corresponding periods from 2015 to 2019. The results showed that LD reduced the frequency and intensity of high-pollution events. Reductions were more relevant during POST-LD than during LD period for all variables, except quasi-ultrafine particles and PM10-2.5. Two events of long-range transport of dust were observed, which need to be identified and removed to determine the effect of LD. The decreases in the quasi-ultrafine particles and eBC concentrations were 20%, and 15–22%, respectively. PM2.5 concentration was reduced by 13–44% whereas PM10-2.5 concentration was unaffected. The concentration of accumulation mode particles followed the behaviour of PM2.5, with reductions of 19–57%. The results obtained could be relevant for future strategies aimed at improving air quality and understanding the processes that influence the number and mass particle size distributions.

Estimating the deposition of polycyclic aromatic hydrocarbons in human airways: The role of particle size

Most previous studies used atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) to estimate the risk of exposure via inhalation, but neglected the disparities in the effects of particle size. In this study, an extensive literature search retrieved data from 35 cities on atmospheric PAHs and particle size distributions, and a multiple-path particle dosimetry model was used to simulate the PAH deposition in human airways. The results revealed that the median concentration of total PAHs was 38 (range, 0.6–2074.2) ng/m3, while the median concentration of benzo(a)pyrene equivalent (B[a]Peq) was 11 ng/m3. Together with exposure to congener-specific PAHs, the median deposited concentrations of total PAHs or B[a]Peq were the highest in particulate matter (PM) with diameters of 1–2.5 μm, followed by > 1 μm and coarse PM, which can be explained by the general increase in proportions of high molecular weight PAHs with decreasing PM size. While the deposited PAHs were dominated by 3–5 rings PAHs, the deposited B[a]Peq was concentrated in 5-ring. Moreover, although differences in the contributions of the ring number between deposited and ambient PAHs were negligible, the contributions of fine PM were 11.9% and 9.5% greater for deposited PAHs and B[a]Peq, respectively. These results indicate that the risk of exposure to PAHs attached to fine PM is underestimated previously.

A new type of electron microscope rapid collection device foratmospheric particles and its application cases.

A device for collecting atmospheric particulates matter for on-line electron microscopy was designed and manufactured by using 3D modeling and printing technology. The device was used to collect atmospheric particulates matter in Xining city of Qinghai province for seven consecutive days and used to collect atmospheric particulates matter in Jinan city of Shandong province for 30 consecutive days. And the samples were analyzed by electron microscopy. Through it can obtain ultra structure and size distribution information of atmospheric particulates matter. The experimental results reflected the distribution of atmospheric particulate matter in real time. The on-line acquisition device for electron microscopy is practical, fast, and convenient, which greatly shortens the sampling period and can be carried to any place outdoors for real-time sampling. The morphological structure and particle size distribution of atmospheric particles in sampling area was observed by electron microscope. The device has reference value to the study of PM2.5 and PM10 in atmosphere and air pollution. This acquisition device is convenient for the detection of sample by electron microscopy. It can further expand and simplify the sampling technology of large-scale instruments and equipment. This new method of real-time monitoring of air pollution is worth popularizing and applying.

Size Distribution of Atmospheric Particles: 40-Year Trends and 20-Year Comparisons of Chemical Constituents between Residential and Roadside Areas in Osaka City, Japan

Long-term observational data for the size distributions and particulate chemical components have been summarized to understand the past and current particulate conditions in Osaka City. The positive matrix factorization (PMF) method was also applied to estimate the source changes. The observational data obtained using Andersen cascade impactors reveals that for the 40 years from fiscal year (FY) 1976 to 2015, there was a 70% reduction in PMfine (less than 2.1 μm of the aerodynamic diameter) and 76% reduction in PMcoarse (over 2.1 μm). These correspond to a 71% and 74% reduction in PM2.5 (particulate matter less than 2.5 μm in diameter) and PM10-2.5, respectively. From the continuous chemical measurements made in this study, we observed a more than 50% reduction in coarse particulate elemental carbon (EC), SO42−, NH4+, Zn, Pb, and Cd, commonly in residential and roadside areas, over the last 20 years. Similarly, the level of the fine particulate EC, Ca2+, Cl−, Zn, Mg2+, Pb, and Cd was reduced by more than 50%. Notably, the results of the particulate component analysis of ECfine show a typical reduction of 73%–79% for 20 years, and this is the main component contributing to the reduction of atmospheric particulate concentration. However, there seems to have been no apparent reduction of Vfine concentrations, SO42−fine showed a relatively low reduction of 19% to 26%, and NH4+fine levels fell by 14% to 21% in 20 years. Since fine sulfate and ammonium have similar behaviors, ammonium sulfate is considered to be a secondary particle aerosol because of long-range transportation. The PMF analysis still estimates a high contribution rate of secondary particles, which is one of the current problems. In contrast, although vanadium is a minor element, it is likely to be generated from harbor areas with ships because they are susceptible to the prevailing sea breeze in summer. Therefore, in the future, it will be necessary to scrutinize and take countermeasures not only for long-range transportation but also for domestic sources.

New particle formation and sub-10 nm size distribution measurements during the A-LIFE field experiment in Paphos, Cyprus

Abstract. Atmospheric particle size distributions were measured in Paphos, Cyprus, during the A-LIFE (absorbing aerosol layers in a changing climate: ageing, lifetime and dynamics) field experiment from 3 to 30 April 2017. The newly developed differential mobility analyser train (DMA-train) was deployed for the first time in an atmospheric environment for the direct measurement of the nucleation mode size range between 1.8 and 10 nm diameter. The DMA-train set-up consists of seven size channels, of which five are set to fixed particle mobility diameters and two additional diameters are obtained by alternating voltage settings in one DMA every 10 s. In combination with a conventional mobility particle size spectrometer (MPSS) and an aerodynamic particle sizer (APS) the complete atmospheric aerosol size distribution from 1.8 nm to 10 µm was covered. The focus of the A-LIFE study was to characterize new particle formation (NPF) in the eastern Mediterranean region at a measurement site with strong local pollution sources. The nearby Paphos airport was found to be a large emission source for nucleation mode particles, and we analysed the size distribution of the airport emission plumes at approximately 500 m from the main runway. The analysis yielded nine NPF events in 27 measurement days from the combined analysis of the DMA-train, MPSS and trace gas monitors. Growth rate calculations were performed, and a size dependency of the initial growth rate (&lt;10 nm) was observed for one event case. Fast changes of the sub-10 nm size distribution on a timescale of a few minutes were captured by the DMA-train measurement during early particle growth and are discussed in a second event case. In two cases, particle formation and growth were detected in the nucleation mode size range which did not exceed the 10 nm threshold. This finding implies that NPF likely occurs more frequently than estimated from studies where the lower nanometre size regime is not covered by the size distribution measurements.

Size distribution and concentration of aerosol particles in Yinchuan area, China

ABSTRACTThe size distribution and concentration of atmospheric aerosol particles are important parameters that characterize the physical and optical properties of aerosols. Understanding the spectral distribution of atmospheric particles is fundamental for studying particulate pollution. Based on observational data acquired by an aerodynamic particle sizer APS-3321 and a laser dust meter LD-5 from September 2017 to July 2018, the temporal evolution of particle size distribution and concentration of aerosols were studied at the North Minzu University in Yinchuan (38°29’52"N 106°06’28"E), China. By cluster analysis of particle surface area distribution in different weathers, seven clusters were obtained and discussed. The experimental results showed that the particle number and mass concentrations were different in the four seasons of the year. Compared with the unimodal distribution of the particle number concentration and the doublet mass concentration distribution in sunny weather conditions, there were great differences in the particle spectrum distribution in haze, snowfall, and dusty weather conditions. The particle surface area distributions of the seven clusters were clearly different from each other and influenced by meteorological conditions. Additionally, the PM2.5 value has a relationship with the meteorological elements. The research is helpful to reveal the formation mechanism and source of aerosols in Yinchuan, China.

Number size distribution of atmospheric particles in a suburban Beijing in the summer and winter of 2015

Particle number size distribution in a suburban Beijing was measured during the HOPE-J3A (Haze Observation Project Especially for Jing–Jin–Ji Area) field campaigns in 2015 from 18 June to 23 July (summer) and 2 to 25 December (winter). Average particle concentrations during the summer and winter campaigns were 9.6 ± 4.8 × 103cm−3 and 13.9 ± 8.3 × 103cm−3, respectively. Particle numbers were dominated by Aitken mode particles in both seasons. During the winter campaign, pollution events occurred every four to five days, each lasting for two to three days. In contrast, pollution events lasted for one to two days every six to seven days during the summer campaign. Aitken mode particles were 50% higher in the winter but new particle formation (NPF) events occurred more frequently in the summer. NPF events usually starts at around 10:00 LT (local time) in the summer but 12:00 LT in the winter. Aitken and accumulation mode particles accounted for 43.5% and 38.2% of all particles. The proportion of Aitken mode to total particles remained almost the same during summer, while it increased as haze intensified in winter. Particle number concentration was closely correlated with traffic and residents living activities and wind speed, with higher concentrations during rush hours, heating period and in the southerly wind. These results, when combined with trajectory cluster analysis, suggest that Aitken and accumulation mode particles were mainly from regional transport during the summer campaign, but from vehicle and coal-combustion emissions during the winter campaign.

Response Characterization of an Inexpensive Aerosol Sensor.

Inexpensive aerosol sensors have been considered as a complementary option to address the issue of expensive but low spatial coverage air quality monitoring networks. However, the accuracy and response characteristics of these sensors is poorly documented. In this study, inexpensive Shinyei PPD42NS and PPD60PV sensors were evaluated using a novel laboratory evaluation method. A continuously changing monodisperse size distribution of particles was generated using a Vibrating Orifice Aerosol Generator. Furthermore, the laboratory results were validated in a field experiment. The laboratory tests showed that both of the sensors responded to particulate mass (PM) concentration stimulus, rather than number concentration. The highest detection efficiency for the PPD42NS was within particle size range of 2.5–4 µm, and the respective optimal size range for the PPD60PV was 0.7–1 µm. The field test yielded high PM correlations (R2 = 0.962 and R2 = 0.986) for viable detection ranges of 1.6–5 and 0.3–1.6 µm, when compared to a medium cost optical dust monitor. As the size distribution of atmospheric particles tends to be bimodal, it is likely that indicatively valid results could be obtained for the PM10–2.5 size fraction (particulate mass in size range 2.5–10 µm) with the PPD42NS sensor. Respectively, the PPD60PV could possibly be used to measure the PM2.5 size fraction (particulate mass in size below 2.5 µm).

Seasonal Variations in Particle Size Distribution and Water-soluble Ion Composition of Atmospheric Particles in Chengdu

Size-resolved atmospheric particles were collected monthly from February 2012 to January 2013 on the campus of Chengdu University of Technology using the Anderson multi-stage impactor sampler. The mass concentrations of these samples and the contents of nine water-soluble ion species were analyzed. The results showed that the annual average concentrations of PM2.1 and PM11 in Chengdu during the sampling period were (125.9±56.14) μg·m-3 and (224.5±83.64) μg·m-3, respectively. The highest mass concentration of particulate matter was observed in winter, followed by spring while the lowest was in autumn. The average content of water-soluble ions in particulate matter in Chengdu was about 37.15 μg·m-3 and the order of water-soluble ion mass concentrations was SO42- > NO3- > NH4+ > Ca2+ > Cl- > Mg2+ > K+ > Na+ > F-. Meanwhile, SO42-, NO3-, and NH4+ were the major water-soluble ionic components that accounted for 78% of total water-soluble ions. Unimodal distribution was observed for SO42-, NO3-, and NH4+ mainly in fine particles, while Ca2+ and F- were concentrated in coarse particles and their distribution was also unimodal. Similar size distributions were found for Cl- and K+, as well as Mg2+ and Na+, both of which were bimodal. The content of water-soluble ions in both fine and coarse particles during winter and spring was significantly higher than that in summer and autumn in Chengdu. Based on the correlation analysis for major ions, SO42-, NO3-, and NH4+ in fine particles are likely in the form of (NH4)2SO4, NH4HSO4, and NH4NO3. In coarse particles, the major water-soluble ions (i.e. SO42-, NO3-, and Ca2+) might exist in the forms of Ca(NO3)2 and CaSO4. The secondary formation processes, soil dust, and biomass burning are the major sources of water-soluble ion species in the particulate matter in Chengdu.

Sub-micron particle number size distribution characteristics at two urban locations in Leicester

The particle number size distribution (PNSD) of atmospheric particles not only provides information about sources and atmospheric processing of particles, but also plays an important role in determining regional lung dose. Owing to the importance of PNSD in understanding particulate pollution two short-term campaigns (March–June 2014) measurements of sub-micron PNSD were conducted at two urban background locations in Leicester, UK. At the first site, Leicester Automatic Urban Rural Network (AURN), the mean number concentrations of nucleation, Aitken, accumulation modes, the total particles, equivalent black carbon (eBC) mass concentrations were 2002, 3258, 1576, 6837 # cm−3, 1.7μgm−3, respectively, and at the second site, Brookfield (BF), were 1455, 2407, 874, 4737 # cm−3, 0.77μgm−3, respectively. The total particle number was dominated by the nucleation and Aitken modes, with both consisting of 77%, and 81% of total number concentrations at AURN and BF sites, respectively. This behaviour could be attributed to primary emissions (traffic) of ultrafine particles and the temporal evolution of mixing layer. The size distribution at the AURN site shows bimodal distribution at ~22nm with a minor peak at ~70nm. The size distribution at BF site, however, exhibits unimodal distribution at ~35nm. This study has for the first time investigated the effect of Easter holiday on PNSD in UK. The temporal variation of PNSD demonstrated a good degree of correlation with traffic-related pollutants (NOX, and eBC at both sites). The meteorological conditions, also had an impact on the PNSD and eBC at both sites. During the measurement period, the frequency of NPF events was calculated to be 13.3%, and 22.2% at AURN and BF sites, respectively. The average value of formation and growth rates of nucleation mode particles were 1.3, and 1.17cm−3s−1 and 7.42, and 5.3nmh−1 at AURN, and BF sites, respectively. It can suggested that aerosol particles in Leicester originate mainly from traffic and domestic heating emissions.

Mass Size Distribution of Atmospheric Aerosol Particles Collected at 865 m High of Jirisan National Park

Mass Size Distribution of Atmospheric Aerosol Particles Collected at 865 m High of Jirisan National Park

Size-resolved simulations of the aerosol inorganic composition with the new hybrid dissolution solver HyDiS-1.0: description, evaluation and first global modelling results

Abstract. The dissolution of semi-volatile inorganic gases such as ammonia and nitric acid into the aerosol aqueous phase has an important influence on the composition, hygroscopic properties, and size distribution of atmospheric aerosol particles. The representation of dissolution in global models is challenging due to inherent issues of numerical stability and computational expense. For this reason, simplified approaches are often taken, with many models treating dissolution as an equilibrium process. In this paper we describe the new dissolution solver HyDiS-1.0, which was developed for the global size-resolved simulation of aerosol inorganic composition. The solver applies a hybrid approach, which allows for some particle size classes to establish instantaneous gas-particle equilibrium, whereas others are treated time dependently (or dynamically). Numerical accuracy at a competitive computational expense is achieved by using several tailored numerical formalisms and decision criteria, such as for the time- and size-dependent choice between the equilibrium and dynamic approaches. The new hybrid solver is shown to have numerical stability across a wide range of numerical stiffness conditions encountered within the atmosphere. For ammonia and nitric acid, HyDiS-1.0 is found to be in excellent agreement with a fully dynamic benchmark solver. In the presence of sea salt aerosol, a somewhat larger bias is found under highly polluted conditions if hydrochloric acid is represented as a third semi-volatile species. We present first results of the solver's implementation into a global aerosol microphysics and chemistry transport model. We find that (1) the new solver predicts surface concentrations of nitrate and ammonium in reasonable agreement with observations over Europe, the USA, and East Asia, (2) models that assume gas-particle equilibrium will not capture the partitioning of nitric acid and ammonia into Aitken-mode-sized particles, and thus may be missing an important pathway through which secondary particles may grow to radiation- and cloud-interacting size, and (3) the new hybrid solver's computational expense is modest, at around 10 % of total computation time in these simulations.

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 2: First results from balloon and unmanned aerial vehicle flights

Abstract. In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60°. That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to size-segregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions (Renard et al., 2016). Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronic-sized absorbing carbonaceous particles in polluted air to very coarse particles (&gt; 10–20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and at ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment – ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 1: Principle of measurements and instrument evaluation

Abstract. The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of µm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12°, and is almost insensitive to the refractive index of the particles; the second one is around 60° and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 µm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20 % when concentrations are higher than 1 particle cm−3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60 % for concentrations smaller than 10−2 particle cm−3. Also, the uncertainties in size calibration are ±0.025 µm for particles smaller than 0.6 µm, 5 % for particles in the 0.7–2 µm range, and 10 % for particles greater than 2 µm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles &gt; 3 µm exceeds a few particles cm−3. Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations.

Atmospheric Particle Size Distributions in the Spanish Network of Environmental DMAs (REDMAAS)

The present work is a first approach to the study of the spatio-temporal variability of the submicrometer atmospheric aerosol in Spain. The aerosol measurements have been obtained simultaneously at seven monitoring stations that compose the REDMAAS network during two measurement campaigns corresponding to summer and winter seasons.In both summer and winter periods those measurement stations with a direct influence of anthropogenic emissions recorded the highest concentrations of particle number. In the summer campaign, the average daily pattern of the aerosol size distribution in the traffic and background urban stations was conditioned by the traffic emissions and secondary aerosol formation through photochemical reactions (new particle formation events, NPF). However, the secondary aerosol had a higher contribution to the aerosol total number concentration in the rural background and high-altitude stations. In the winter campaign, in all sampling sites with the exception of Izaña station, the traffic and domestic activity emissions had a greater contribution than secondary aerosol formation on particle number total concentration.New particle formation events were identified at all sites during the summer period, and at sites without direct influence of anthropogenic emissions during the winter campaign. Some aerosol shrinkage processes were also observed at the Madrid and El Arenosillo stations.

Seasonal dynamics of coarse atmospheric particulate matter between 2.5 μm and 80 μm in Beijing and the impact of 2008 Olympic Games

Beijing is well known as a megacity facing severe atmospheric pollution problems. One very important kind of pollution is the high amount of particles in Beijing's atmosphere. Numerous studies investigated the dynamics of fine particles smaller 10 μm. Less information is available on the coarse particle fraction larger 10 μm, although geogenic dusts, which often are composed by those coarser particles, frequently affect the air quality in Beijing. Therefore, systematic sampling and analysis of size fractionated particulate matter between 2.5 and 80 μm was performed in Beijing from April 2005 till October 2009. Atmospheric particles were collected in the North-West of Beijing using a cost-effective passive sampling method called Sigma-2. Altogether, 200 weeks could be analysed and assessed. Concentrations and size distribution of atmospheric coarse particles were determined by automated microscopic single particle analysis. Seasonal variability of the total mass of different size fractions was identified as follows: spring > winter > autumn > summer. High concentrations of transparent mineral particles indicate the activity of geogenic sources in spring and winter time, due to asian dust events and resuspension of soil from local bare land during dry and windy periods. The percentage of opaque particle components differs seasonally with relatively high values in winter, confirming combustion of fossil fuels for heating purposes as a predominant pollution source in this season. The influence of meteorological conditions on concentrations and size distribution of atmospheric particulate matter between 2.5 and 80 μm is demonstrated for the whole sampling period. Lowest pollution by coarse aerosols occurred during the period of the 2008 Olympic Summer Games. A general trend of decreasing total coarse particle mass concentrations was observed. Due to frequently observed high total coarse particle mass concentrations of several 100 μg·m−³ it is strongly recommended to enhance research and observation regarding these air pollutants to gain a better understanding of their dynamics, health effects, well being impacts on Beijing inhabitants and the effectiveness of mitigation measures.

Submicron particle concentration and particle size distribution at urban and rural areas in the surroundings of building materials industries in central Spain

Particle number concentrations and size distribution of atmospheric aerosol particles were measured in the range 6560nm by a fast mobility particle sizer in Toledo, Spain, and in the outskirts of nearby small villages within the area of influence of a cement factory, quarries and ceramic industries. Several measurement campaigns have been carried out in different days in Toledo (April, May and July) and one campaign in “Comarca de la Sagra” in July. In each campaign, measurement of 10–15 min has been achieved in several different points. In addition, a campaign of continuous measurements has been carried out in Toledo. The average number concentration in Toledo are consistent with other urban measurements, with lower values during the night–time ranging from 3×103 to 1×104 particles/cm3 and higher average levels during daytime ranging from 5×103 to 4×104 particles/cm3 depending on the measurement site and date. The measurement sites show similar background profiles of the particle size distributions with two clear particle modes centered in the sizes ranges 10–15 and 40–50nm. Road traffic is postulated as the main source of submicron particles, giving lower level of particles during the summer time. Results from continuous measurements have been analyzed. On the other hand, the low total concentrations obtained in the “Comarca de la Sagra” campaign, ranging from 1.5×103 to 3.1×103 particles/cm3 with an average value of 2.3×103 particles/cm3, show a negligible influence of the different building materials industries on the total submicron particle concentration in the surrounding area and in Toledo.

Size-dependent distribution and inhalation cancer risk of particle-bound polycyclic aromatic hydrocarbons at a typical e-waste recycling and an urban site

Atmospheric particle size distribution of polycyclic aromatic hydrocarbons (PAHs) in a typical e-waste recycling zone and an urban site (Guangzhou) in southern China featured a unimodal peak in 0.56–1.8 μm for 4–6 ring PAHs but no obvious peak for 2–3 ring PAHs at both sites. The atmospheric deposition fluxes of PAHs were estimated at 5.4 ± 2.3 μg m−2 d−1 in the e-waste recycling zone and 3.1 ± 0.6 μg m−2 d−1 in Guangzhou. In addition, dry and wet deposition fluxes of PAHs were dominated by coarse (Dp > 1.8 μm) and fine particles (Dp < 1.8 μm), respectively. Fine particles predominated the deposition of PAHs in the lung. The results estimated by incremental inhalation cancer risk suggested that particle-bound PAHs posed serious threat to human health within the e-waste recycling zone and Guangzhou.

Attenuation for Multiple Scattering of Laser in Atmospheric Aerosols

In this paper, the scattering parameters of aerosol particles are calculated based on Gamma model of atmospheric particle size distribution and the Mie scattering theory for 0.53μm、1.06μm and 10.6μm laser. For the transmission attenuation of the laser in aerosol, the Monte Carlo simulation model is established. The transmittances with propagation distance are calculated for three kinds of wavelength laser in the continental, marine and cumulus aerosols respectively. The results show three kinds of wavelength laser transmission attenuation in cumulus clouds are far stronger than in the continental and marine aerosol. The transmission performance of 10.6μm laser is best in continental aerosol. For marine aerosol, the attenuation to 0.53μm laser is stronger than to 1.06μm and 10.6μm.