How harmful is smog?

Also known as Haze, dust, sulfuric acid, nitric acid, organic hydrocarbons and other particulate matter in the air make the atmosphere turbid, blur vision and worsen visibility. If the horizontal visibility is less than 65,438+00,000 meters, the visual distance obstacle caused by this aerosol system composed of non-aquatic products is called haze or dust haze, and the Hong Kong Observatory calls it haze.

The difference between haze and fog is that the relative humidity is small when haze occurs, but it is saturated in fog (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur). Generally speaking, the visibility deterioration caused by atmospheric haze blurred vision is caused by haze when the relative humidity is less than 80%, while the visibility deterioration caused by atmospheric haze blurred vision is caused by fog when the relative humidity is more than 90%. The visibility deterioration caused by atmospheric haze blurred vision is caused by a mixture of haze and fog when the relative humidity is between 80 and 90%, but its main component is haze. The thickness of haze is relatively thick, which can reach about 1-3 km. Haze is different from fog and clouds, and there is no obvious boundary between haze and clear sky. Smog particles are evenly distributed, and the particle size is relatively small, ranging from 0.00 1 micron to 10 micron, with an average diameter of about 1-2 micron. Floating particles are invisible to the naked eye. Because the smog is composed of dust, sulfuric acid, nitric acid and other particles, the longer the scattering wavelength, the more the light ratio, so the smog looks yellow or orange-gray.

fog

Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground, and it is the product of condensation (or sublimation) of water vapor in the air near the ground. The existence of fog will reduce air transparency and worsen visibility. If the horizontal visibility of the target drops below 1000m, the weather phenomenon of water vapor condensation (or condensation) suspended in the air near the ground is called fog. The phenomenon that the horizontal visibility of the target is 1000- 10000 meters is called light fog or mist. When fog is formed, the atmospheric humidity should be saturated (if there are a large number of condensation nuclei, the relative humidity may not reach 100%, and saturation may occur). As far as its physical essence is concerned, fog and cloud are the products of condensation (or condensation) of water vapor in the air, so fog becomes a cloud when it rises from the ground, and it is called fog when it falls to the ground or moves to the mountains. Generally, the thickness of fog is relatively small, and the thickness of common radiation fog is between tens of meters and one hundred and two hundred meters. Fog, like clouds, has obvious boundary with clear sky area, and the droplet concentration distribution is uneven. The droplet size is large, ranging from a few microns to 100 micron, with an average diameter of about 10-20 micron. The naked eye can see the droplets floating in the air. Because the light scattered by fog composed of liquid water or ice crystals has little to do with wavelength, the fog looks milky white or bluish white. With the deterioration of air quality, cloudy days are increasing and the harm is increasing. Recently, many areas in China have incorporated the smog weather phenomenon into the fog as an early warning and forecast of disastrous weather. Collectively referred to as "haze weather".

Hazards of smog

With the deterioration of air quality, cloudy days are increasing and the harm is increasing. Recently, many areas in China have incorporated the smog weather phenomenon into the fog as an early warning and forecast of disastrous weather. Collectively referred to as "haze weather". In fact, fog and haze are completely different to some extent. For example, when fog appears, the air is humid; When smog occurs, the air is relatively dry and the relative humidity of the air is usually below 60%. The reason is that a large number of extremely fine dust particles, smoke particles and salt particles float in the air evenly, so that the air with effective horizontal visibility less than 10KM is mixed together. The symbol is "∞". The diurnal variation of haze is generally not obvious. When the air mass changes little and is stable, it lasts for a long time, sometimes exceeding 10 days. Due to weather phenomena such as haze, light fog, sandstorm, sand blowing, floating dust and smoke, the effective horizontal visibility is less than 10KM due to a large number of extremely fine dust particles or smoke particles floating in the air. Sometimes it is difficult for meteorological professionals to tell the difference. It is necessary to comprehensively analyze and judge the weather background, sky conditions, air humidity, color and smell, satellite monitoring and other factors in order to draw a correct conclusion. The weather phenomena of fog and haze can sometimes be converted to each other. Smog is harmful to the human body after being inhaled into the human respiratory tract, and it can be fatal in serious cases.