Growth rates of fine aerosol particles at a site near Beijing in June 2013

The satellite-derived aerosol optical depth (AOD) data is used to investigate the distribution of aerosol over the South China Sea (SCS). High correlation coefficients are found between in situ AERONET data and satellite AOD measurements around the SCS with the highest coefficient of 0.9 on the Dongsha Island (i.e., Pratas Island). The empirical orthogonal function (EOF) analysis of AOD over the SCS shows that high AOD is always found around offshore areas of China, Indochina, Sumatra, and Borneo. Besides, spring is the major season of occurring coarse aerosol particles (AOT_C) but fine aerosol particles (AOT_F) occur yearly. The biomass burning is found in Indochina during March and April, and so it is in Sumatra and Borneo from August to October. The results also show that the AOT_F are higher during El Niño events, but higher AOT_C are found in La Niña years.

Download Full-text

On the filtration of fine aerosol particles by a dual-wire fibre filter

Journal of Electrostatics ◽

10.1016/s0304-3886(96)00047-2 ◽

1997 ◽

Vol 39 (2) ◽

pp. 145-153 ◽

Cited By ~ 1

Author(s):

M. Chiruţa ◽

M. Slaninǎ ◽

M. Duca

Keyword(s):

Aerosol Particles ◽

Fine Aerosol

Download Full-text

Formation and characteristics of ions and charged aerosol particles in a native Australian Eucalypt forest

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-129-2008 ◽

2008 ◽

Vol 8 (1) ◽

pp. 129-139 ◽

Cited By ~ 96

Author(s):

T. Suni ◽

M. Kulmala ◽

A. Hirsikko ◽

T. Bergman ◽

L. Laakso ◽

...

Keyword(s):

Growth Rates ◽

Aerosol Particles ◽

Particle Formation ◽

Cluster Ions ◽

Native Forest ◽

New Particle Formation ◽

Aerosol Formation ◽

Eucalypt Forest ◽

The World ◽

Strong Source

Abstract. Biogenic aerosol formation is likely to contribute significantly to the global aerosol load. In recent years, new-particle formation has been observed in various ecosystems around the world but hardly any measurements have taken place in the terrestrial Southern Hemisphere. Here, we report the first results of atmospheric ion and charged particle concentrations as well as of new-particle formation in a Eucalypt forest in Tumbarumba, South-East Australia, from July 2005 to October 2006. The measurements were carried out with an Air Ion Spectrometer (AIS) with a size range from 0.34 to 40 nm. The Eucalypt forest was a very strong source of new aerosol particles. Daytime aerosol formation took place on 52% of days with acceptable data, which is 2–3 times as often as in the Nordic boreal zone. Average growth rates for negative/positive 1.5–3 nm particles during these formation events were 2.89/2.68 nmh−1, respectively; for 3-7 nm particles 4.26/4.03, and for 7–20 nm particles 8.90/7.58 nmh−1, respectively. The growth rates for large ions were highest when the air was coming from the native forest which suggests that the Eucalypts were a strong source of condensable vapours. Average concentrations of cluster ions (0.34–1.8 nm) were 2400/1700 cm−3 for negative/positive ions, very high compared to most other measurements around the world. One reason behind these high concentrations could be the strong radon efflux from the soils around the Tumbarumba field site. Furthermore, comparison between night-time and daytime concentrations supported the view that cluster ions are produced close to the surface within the boundary layer also at night but that large ions are mostly produced in daytime. Finally, a previously unreported phenomenon, nocturnal aerosol formation, appeared in 32% of the analysed nights but was clustered almost entirely within six months from summer to autumn in 2006. From January to May, nocturnal formation was 2.5 times as frequent as daytime formation. Therefore, it appears that in summer and autumn, nocturnal production was the major mechanism for aerosol formation in Tumbarumba.

Download Full-text

Regional Deposition of Inhaled Monodisperse Coarse and Fine Aerosol Particles in Small Laboratory Animals

The Annals of Occupational Hygiene ◽

10.1093/annhyg/32.inhaled_particles_vi.53 ◽

1988 ◽

Cited By ~ 120

Keyword(s):

Aerosol Particles ◽

Laboratory Animals ◽

Small Laboratory ◽

Regional Deposition ◽

Fine Aerosol

Download Full-text

Measurement Report: Impact of African Aerosol Particles on Cloud Evolution in a Tropical Montane Cloud Forest in the Caribbean

10.5194/acp-2021-88 ◽

2021 ◽

Author(s):

Elvis Torres-Delgado ◽

Darrel Baumgardner ◽

Olga L. Mayol-Bracero

Keyword(s):

Cloud Forest ◽

Cloud Condensation Nuclei ◽

Aerosol Particles ◽

Liquid Water Content ◽

Tropical Montane Cloud Forest ◽

Microphysical Properties ◽

Montane Cloud Forest ◽

The Caribbean ◽

A Site ◽

Cloud Evolution

Abstract. African aerosol particles, traveling thousands of kilometers before reaching the Americas and the Caribbean, directly scatter and absorb solar radiation and indirectly impact climate by serving as cloud condensation nuclei (CCN) or ice nuclei (IN) that form clouds. These particles can also affect the water budget by altering precipitation patterns that subsequently affect ecosystems. As part of the NSF-funded Luquillo Critical Zone Observatory, field campaigns were conducted during the summers of 2013, 2014, and 2015 at Pico del Este, a site in a tropical montane cloud forest on the Caribbean island of Puerto Rico. Cloud microphysical properties, which included liquid water content, droplet number concentration, and droplet size, were measured. Using products from models and satellites, as well as in-situ measurements of aerosol optical properties, periods of high and low dust influence were identified. The results from this study suggest that meteorology and air mass history have a more important effect on cloud processes than aerosols transported from Africa. In contrast, air masses that arrived after passing over the inhabited islands to the southeast led to clouds with much higher droplet concentrations, presumably due to aerosols formed from anthropogenic emissions.

Download Full-text

Efficacy of Ventilation, HEPA Air Cleaners, Universal Masking, and Physical Distancing for Reducing Exposure to Simulated Exhaled Aerosols in a Meeting Room

Viruses ◽

10.3390/v13122536 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2536

Author(s):

Jayme P. Coyle ◽

Raymond C. Derk ◽

William G. Lindsley ◽

Francoise M. Blachere ◽

Theresa Boots ◽

...

Keyword(s):

Indoor Environment ◽

Aerosol Particles ◽

Personal Exposure ◽

Mitigation Strategies ◽

Face To Face ◽

Meeting Room ◽

Aerosol Exposure ◽

Fine Aerosol ◽

Unit Increase ◽

Air Cleaners

There is strong evidence associating the indoor environment with transmission of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 can spread by exposure to droplets and very fine aerosol particles from respiratory fluids that are released by infected persons. Layered mitigation strategies, including but not limited to maintaining physical distancing, adequate ventilation, universal masking, avoiding overcrowding, and vaccination, have shown to be effective in reducing the spread of SARS-CoV-2 within the indoor environment. Here, we examine the effect of mitigation strategies on reducing the risk of exposure to simulated respiratory aerosol particles within a classroom-style meeting room. To quantify exposure of uninfected individuals (Recipients), surrogate respiratory aerosol particles were generated by a breathing simulator with a headform (Source) that mimicked breath exhalations. Recipients, represented by three breathing simulators with manikin headforms, were placed in a meeting room and affixed with optical particle counters to measure 0.3–3 µm aerosol particles. Universal masking of all breathing simulators with a 3-ply cotton mask reduced aerosol exposure by 50% or more compared to scenarios with simulators unmasked. While evaluating the effect of Source placement, Recipients had the highest exposure at 0.9 m in a face-to-face orientation. Ventilation reduced exposure by approximately 5% per unit increase in air change per hour (ACH), irrespective of whether increases in ACH were by the HVAC system or portable HEPA air cleaners. The results demonstrate that mitigation strategies, such as universal masking and increasing ventilation, reduce personal exposure to respiratory aerosols within a meeting room. While universal masking remains a key component of a layered mitigation strategy of exposure reduction, increasing ventilation via system HVAC or portable HEPA air cleaners further reduces exposure.

Download Full-text