I. Origin of haze weather
Fog and haze are two different weather phenomena from a meteorological point of view. The main characteristic of fog is the near-surface layer, which is probably no more than 400 meters high and is composed of tiny water droplets inside the air layer below this. The presence of fog reduces air transparency and deteriorates visibility. If the horizontal visibility of the target is reduced to less than 1000 meters, the weather phenomenon of water vapor condensation (or condensation) suspended in the air near the ground is called fog (Fog), while the horizontal visibility of the target at 1000-10000 meters is called light fog or mist (Mist).
Formation of fog when the atmospheric humidity should be saturated, in terms of its physical nature, fog and clouds are the product of water vapor condensation in the air, so the fog rises off the ground to become clouds, and clouds lowered to the ground or clouds move to the mountains when it is called fog. The general thickness of fog is relatively small, the common thickness of radiation fog from a few dozen meters to about one to two hundred meters.
Fog and clouds, like the clear sky area, there is a clear boundary between the fog droplet concentration distribution is not uniform, and the fog droplet diameter is relatively large, from a few microns to 100 microns, the average diameter of about 10-20 microns, the naked eye can see the air floating fog droplets. The fog looks milky or greenish-white because the light scattered by the fog composed of liquid water or ice crystals has little relation to the wavelength.
The main component of haze is a kind of dust, usually called dust, such as sulfuric acid, nitric acid and some such tiny particles. Haze is thicker, up to about 1-3 km. The difference between haze and fog is that the relative humidity is not high when haze occurs, while the relative humidity in fog is saturated.
The deterioration of visibility due to blurred vision of atmospheric haze when the relative humidity is less than 80% is generally caused by haze, the deterioration of visibility due to blurred vision of atmospheric haze when the relative humidity is greater than 90% is caused by fog, and the deterioration of visibility due to blurred vision of atmospheric haze when the relative humidity is between 80-90% is caused by a mixture of haze and fog together, but its main component is haze. Unlike fog and clouds, there is no clear boundary between haze and clear sky area, and the distribution of haze particles is more uniform;
Moreover, the diameter of haze particles is relatively small, from 0,001 microns to 10 microns, with an average diameter of about 1-2 microns, and the particles floating in the air are invisible to the naked eye. Since the haze composed of dust, sulfuric acid, nitric acid and other particles scatter more light with longer wavelengths, the haze looks yellow or orange-gray.
With the deterioration of air quality, the haze phenomenon has increased and the harm has worsened, therefore, many regions in China have incorporated the haze weather phenomenon into fog as a catastrophic weather warning forecast, collectively referred to as “haze weather”.
Second, the main hazards of hazy weather on the human body
It is often said that “autumn and winter poisonous fog killing knife”. We can see and catch the “haze” actually has a greater impact on the body, especially on the elderly groups with a high incidence of cardiovascular and respiratory diseases.
1, the impact on the respiratory system. The composition of haze is very complex, including hundreds of atmospheric chemical particulate matter. Among them, those harmful to health are mainly aerosol particles less than 10 microns in diameter, such as mineral particles, sea salt, sulfate, nitrate, organic aerosol particles, fuel and automobile exhaust, etc. It can directly enter and adhere to the human respiratory tract and alveoli.
In particular, submicron particles can be deposited in the upper and lower respiratory tracts and alveoli, respectively, causing conditions such as acute rhinitis and acute bronchitis. For patients with chronic respiratory diseases such as bronchial asthma, chronic bronchitis, obstructive emphysema and chronic obstructive pulmonary disease, hazy weather can cause acute attacks or acute exacerbation of the disease. If long-term in this environment will also induce lung cancer.
2, the impact on the cardiovascular system. Hazy weather air pollutants, low gas pressure, easy to induce acute attacks of cardiovascular disease. For example, when the fog is high, the water vapor content is very high, if people are outdoors and exercise, the body’s sweat is not easy to discharge, resulting in chest tightness and increased blood pressure.
3, foggy weather can also lead to a weakening of the near-earth layer of ultraviolet light, so that the activity of infectious bacteria in the air is enhanced, the increase in infectious diseases.
4, due to reduced sunlight in foggy weather, children’s UV exposure is insufficient, the body does not generate enough vitamin D, the absorption of calcium is greatly reduced, serious will cause rickets in infants, children’s growth slowed.
5, affect mental health. Gloomy foggy weather due to the weak light and the resulting low pressure, easy to produce mental laziness, depressed and pessimistic mood, encounter unhappy things and even easy to lose control.
6, affect traffic safety. Haze weather, low visibility, poor air quality, easy to cause traffic congestion, traffic accidents.
Third, the haze weather how to prevent disease
Hazy weather is the formation of natural and man-made pollution of the environment, the face of this bad weather, we can only take various measures to try to avoid its normal life and health hazards to people.
1. Reduce going out. The elderly and children with weak resistance and susceptible people with respiratory diseases should minimize going out or reduce outdoor activities, wear a mask to protect the body when going out to prevent pollutants from invading the lungs by nose and mouth, and wash the face and bare skin immediately after returning from going out.
2. Reduce outdoor exercise. Hazy weather pressure is low, visibility is low, the air is suspended in a large number of dust and other toxic particles, suffering from bronchial asthma, chronic bronchitis, obstructive emphysema and chronic obstructive pulmonary disease and other chronic respiratory disease patients, should try to avoid outdoor exercise, so as not to induce the onset of chronic disease or aggravation. Similarly foggy weather pressure is low, hypertension, coronary heart disease and other chronic diseases patients should not do outdoor exercise to avoid inducing angina, heart failure.
Moderate and heavy haze weather is prone to irritation of the human respiratory and circulatory system, especially in the morning when air quality is poor. Generally speaking, if there is no cold air activity and rain, snow, wind and other weather, exercise time is best to choose the morning to the evening before the air quality is good, high visibility time, the location of more trees and grass is good, haze weather should also moderate the amount of exercise and exercise intensity.
3. Close doors and windows. Because of hazy weather, the air is difficult to dissipate pollutants, in the foggy weather should be closed doors and windows to avoid outdoor fog into the indoor pollution of indoor air, inducing the occurrence of acute respiratory and cardiovascular diseases.
4, pay attention to diet. Patients with chronic respiratory diseases, especially the elderly should maintain a scientific routine, avoid overexertion and drink more water. Pay attention to a light diet, eat less stimulating food, eat more tofu, milk and other foods, and supplement vitamin D when necessary.
5, driving and walking with extra care. In moderate and heavy haze, visibility is low, poor vision, people driving, cycling and walking should be more careful, especially through intersections and unattended railroad crossings, slow down and obey the rules of the road to avoid traffic accidents.