Aerosols

A government advisory to contain Covid-19 has said that aerosols could be carried in the air for up to 10 metres and improving the ventilation of indoor spaces would reduce transmission.

An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas.
Aerosol or particulate matter (PM) is typically defined by size, with the smaller particles having more health impact. Commonly quoted values for PM are total particulate matter (TPM) or total suspended particles (TSP)- particles with a diameter <10 µm (PM10) and particles with a diameter <2.5 µm (PM2.5).
In the atmosphere, these particles are mainly situated in the lower layers of the atmosphere since aerosol sources are located on the terrestrial surface.
Certain aerosols can be found in the stratosphere, especially volcanic aerosols ejected into the high altitude layers.
They are generated by natural sources (i.e., wind-borne dust, sea spray, volcanic debris, biogenic aerosol) and/or anthropogenic activities (i.e., sulfates and nitrates from industrial emissions, wind-forced mineral dust mobilized in areas exploited for agricultural activities, fossil fuel combustion, and waste and biomass burning).

Can change the atmospheric chemical composition
Affect human health (Inhalation into lungs)
Reduce visibility
Change air quality
They serve as nuclei for cloud droplets or ice crystals in ice clouds. Aerosols can therefore affect regional cloud properties and may affect precipitation amounts.

The system for air quality forecasting and research (SAFAR) has been operationalized by IMD to monitor and forecast air quality of a metropolitan city. This is a joint project of IIT- Madras and IMD.
It is a national initiative introduced by the Ministry of Earth Sciences (MoES)
All major air pollutants (PM2.5, PM10, Ozone, CO, NOx (NO, NO2), SO2, BC, Methane (CH4), Non-methane hydrocarbons (NMHC), VOC’s, Benzene, Mercury), solar radiation and meteorological parameters are measured at ten air quality station installed in each city.
SAFAR provides location specific information on air quality in near real time.
It has an LED display that gives out a real-time air quality index on a 24×7 basis with color-coding (along with 72 hours advance forecast).

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