What aerosol transmission is?

Speaking of the spread of aerosols, aerosol can from what is talked about. When you stay home watching videos, suddenly smell wafted from the kitchen of an burning smell; someone around when suddenly sneezed or subway; Or you magnificent view overlooking the sunset from the window …… these in your life scenes often encountered, because of the presence of aerosols.

火山喷发的景象
volcanic eruption scene

What is an aerosol?

aerosols (Aerosols), means suspended fine particles in the atmosphere. For example, we usually say clouds, fog, haze and the like are considered aerosols. The suspension of fine particles in the air, the size is generally from 0.001 ~ 100μm (microns). The maximum 100μm how much of it? We know that, corresponding to a 1 micron thousandth of a millimeter, corresponding to the maximum value of 100 [mu] m 0.1 mm so large, and the minimum is one thousandth of a millimeter, the naked eye can not see. Under the microscope, the diameter of the droplet is less than 100 m, air pollutant particles less than 10 microns. 气溶胶的传播是什么? In addition to the minute, the shape of these particles is varied, and some nearly spherical, such as a bead of liquid fog, while others are flaky, needle-like, and other irregular shapes. These particles can scatter or absorb sunlight, and therefore, if the particles are large enough, can be visually observed. Aerosol air to reduce the visibility of sunlight scattering (i.e., haze is formed), but also allows more red sunrise and sunset look more visible.

巴厘岛的日出景象
Bali sunrise

Aerosol Science is an emerging interdisciplinary cross. It is due to the development and modernization of industry, the major problems of human health, atmospheric environmental protection, global climate change and other closely related, in recent years a new dynamic area. .

sources of aerosols

1 nature

suspended fine particles in the atmosphere, some from nature: for example, the formation of forest fires this year, Australia\’s \”Fire cloud \”, the smoke and tiny particles to converge at low altitude in the stratosphere (similar to the phenomenon that occurs when volcanic eruptions), seriously affecting air quality. There are those windblown soil particles, sea water splashing Young into the atmosphereAfter the fine particles and cosmic dust and the like are evaporated salt particles, bacteria, microbes, spores and pollen of plants, meteor generated by combustion, belong to the aerosol. .

2 Human Behavior

Some aerosol created by man himself: due to human activities, such as coal burning material, oil and other fossil fuels, as well as to the exhaust gas emissions from vehicle a large number of soot and the like in the air. For example, the main constituents of haze sulfate aerosols, coal is the culprit. When the aerosol concentration is high enough, it will pose a threat to human health, especially for people with asthma and other respiratory diseases have the crowd. Air aerosol can spread fungus and viruses can cause epidemics and outbreaks of disease in some areas. Studies have shown that: suspended particles produced significant impact (such as the spread of new crown pneumonia) on human health will be , especially in water-soluble aerosol components greater impact on human health. [2] and to eliminate aerosol, mainly by atmospheric precipitation, and the abutment between the small particles, agglomeration, aggregation and settling process. 气溶胶的传播是什么?

Third, the spread of aerosols

microbial aerosols is one of the important factors of environmental pollution, biological pollution aerosols can cause a series of popular infectious diseases. In this new crown epidemic, the spread refers to the aerosol droplets mixed in the air to form an aerosol, inhalation lead to infection. In the laboratory, the degree of harm depends on the microorganism itself microbial aerosols virulence, concentration, particle size, and microclimate conditions in the laboratory at that time. Laboratory environment more suitable for living organisms, the greater the likelihood of laboratory infection and may spread to other parts of the same building by the air flow, air pollution and even entire buildings. Microbial respiratory tract mainly in the aerosol. About aerosols in the human living environment of communication, to name a few everyday examples:

generated when the flush the toilet \’spray poop. \”

In 1975, Baylor College of Medicine in the toilet thinking of life researcher insight into Charles Gerba et al., generated when the toilet flush bioaerosol (suspended solid or liquid system is formed in air). To prove it, he fell to the bacteria in the toilet, then in the vicinity of the toilet from differentFrom where arranged the dish, then rushing Wow hard to flush the toilet. As expected, two hours after Flush toilets, bacteria basically fall on the floor near the toilet. but! Flush the toilet after 4-6 hours, the whole toilet can detect bacteria into the septic tank should have been up. Also surprising is that in the bathroom shampoo water bottles following a large number of E. coli was found. Pathologist at New York University\’s Philip Tierno said the poo …… Well aerosol spray can is irradiated height 4.6 m, which is 2 floors so high, so it is taking a poetic and intimate name insiders – toilet smoke Yu (toilet plume). Opening the lid of the case where the toilet, the toilet from the upper 25 cm can be detected poo bacteria that float on the distance up to a half hour. But if the toilet lid covered with red, then the amount of bacterial aerosols only open lid condition 1/12. Obviously, they do not cover the lid after flushing, you will enjoy a fine spray of going to the toilet, it may be even more uniform than French perfume spray method.

虹吸式马桶(左)和直冲式马桶(右)
siphon toilet (left) and straight into the toilet (Right)

straight and siphon type, which is not easy to produce aerosol poo it? In 1959, a study published in the \”Lancet\” (The Lancet) found If it is straight into the toilet, then after each flush toilet in the concentration of microorganisms will drop 99% in air bioaerosols decreased by 50 to 60%. However, if the aerosol produced after siphonic toilet, the toilet flushing only with the displacement straight toilets 1/14.

electronic cigarette aerosol

In recent years, popular electronic cigarette high osmolarity glycerol, water, population will dry, dry throat, used aerosol electronic cigarette It has become a new source of air pollution.

电子烟通过加热雾化产生气溶胶供烟民吸入
by heating the electronic cigarette smokers atomized aerosol for inhalation

World Health Organization, the aerosol generated in the electronic cigarette, typically comprising ethylene glycol, aldehydes, volatile organic compounds, polycyclic aromatic hydrocarbons, nitrosamines in tobacco, metal, silicate particles and glyoxal, methylglyoxal, diacetyl, acetone, alcohol and the like, many of which are knownOn the health effects of toxic substances. From the conceptual point of view larger, give the aerosol chemical reaction (heterogeneous reaction) spaces provided in the Earth\’s atmosphere. The most serious impact of such a chemical reaction caused by the destruction of stratospheric ozone. In the winter polar regions increased aerosols, stratospheric clouds form the polar regions. These large surfaces of cloud particles is the best place chemical reaction occurs. Chemical reactions produce large amounts of active chlorine, eventually resulting in destruction of stratospheric ozone. Available evidence suggests that, after large volcanic eruptions, similar changes in stratospheric ozone concentration characteristics appear, for example, Mount Pinatubo Philippines in 1991 (Mt. Pinatubo) eruption has caused the number of tons of volcanic aerosol boom into the atmosphere.

美国宇航局(NASA)
NASA (NASA)

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