According to the National Satellite Meteorological Center, at 13:30 on November 13, 2018 (Beijing time), the FY-4A geostationary satellite combined with ground PM2.5 concentration observations (Fig. 1): in the cloudless and cloudless coverage areas, Beijing, Tianjin In Hebei, most of Henan, and the western part of Shandong, there is moderate to severe weather, and the plains appear to be mild to moderate.

Figure 1: FY-4A geostationary satellite monitoring image November 13, 2018

Winter fog is known as the "winter killer", plus industrial waste gas, automobile exhaust, dust in the air, bacteria and viruses in the air, attached to these water droplets, people in daily life and travel, these substances will It has an effect on the respiratory tract of the human body. In the haze, people should try to reduce outdoor activities. In addition to the effects of PM2.5 and PM10 particles on the respiratory tract and lungs, bioaerosol is also a factor that cannot be ignored.

Bioaerosol

A large number of bacteria, viruses, fungi and allergenic pollen, mold spores, fern spores and parasite eggs are suspended in atmospheric particles such as PM2.5 and PM10. Some of them are alive in the air and can even self-reproduce. Therefore, we refer to aerosols containing microorganisms or biological substances with aerodynamic diameters within 100 microns as bioaerosols.

What are the effects and hazards of bioaerosols?

1. Agriculture and human health: the spread of organisms including pathogens and allergens

2. Hydrological cycle and climate: direct scattering of solar radiation; cloud condensation, ice condensation, and other deposits

Bioaerosol detection method

Traditional mechanical sampling: filter, impact, compression

Limitations of traditional methods:

1, can not be real-time online monitoring

2, can not be single particle measurement

Bio-Aerosol Analyzer (WIBS-NEO)

The Bio-Aerosol Analyzer (WIBS-NEO) is an advanced device for real-time, online, single-particle measurement that provides features and complete particle characterization. The instrument uses a UV-ray source to excite a single-particle aerosol to produce fluorescence. Compared to an ultraviolet laser source, the UV-ray source can accurately select a specific UV wavelength, greatly improving the measurement of bioaerosol (tryptophan, The accuracy of NADH).

Schematic

WIBS-NEO output parameters

There are five measured information for each particle

• FL1_280: Fluorescence emission between 310-400 excited at 280 nm (including tryptophan)

• FL2_280: Fluorescence emission between 420 and 650 excited at 280 nm

• FL2_370: Fluorescence emission between 420 and 650 excited at 370 nm (including NADPH)

• Optical size: 0.5-30 μm, 635nm laser light scattering signal (related to particles)

• Aspherical factor: judge particle shape

WIBS-NEO application case

Study on Characteristics of Marine Aerosols Based on Fluorescence Signals

Figure: Fluorescence particle number concentration time series of different channels in Shenzhen Nanao and Shaoguan Nanling

In this study, the dual-band fluorescence bio-aerosol (WIBS) was used to observe the atmospheric observations of the Nanhai and Shaoguan Nanling monitoring points as the sea-land source background points, and the bio-aerosol characteristics of the sea-land source were obtained. Using the correlation analysis of black carbon, acetonitrile and m/z44 with different types of fluorescent particles, Shenzhen Nan'ao and Shaoguan Nanling are less affected by abiotic components and can better represent sea-land source bioaerosol. The particle size characteristics of the summer fluorescent particles in Hailuyuan and Shenzhen 15a were further compared. The PMF model was used to obtain a contribution of 0.020 cm-3 to the summer bioaerosol in Shenzhen, accounting for 2.9% of the total fluorescent particles.

Source: Ren Yi, Huang Xiaofeng et al. Study on the characteristics of marine aerosols based on fluorescence signals[J]. Environmental Science and Technology, 2018, 41(7): 91-96.

Life tips

Since we are already familiar with the "winter killer", how should we deal with it in our daily life?

1, less open the window

2, indoor multi-green plants

3, eat light and drink plenty of water

4, smog day out wearing a mask