Photochemical smog (photosmog), or Los Angeles-type smog, is in the form of a brown fog hovering over the city. Photochemical smog is typical for many large urban agglomerations with intensive industrial production and heavy car traffic. Photochemical smog occurs in summer, but is as dangerous to he alth as smog observed in winter. Check how photochemical smog is formed, what is its composition, how it affects he alth and how it differs from acid smog.
Contents:
- Photochemical smog - how is it formed?
- Photochemical smog - impact on he alth
- Photochemical smog - who is particularly vulnerable?
- Photochemical vs sour smog
Photochemical smog , also known as photosmog, Los Angeles-type, Tokyo-type, Sao Paulo-type smog, white or light smog, oxidizing smog, this is smog whose main ingredients are chemically active organic compounds (peroxides, aldehydes) and ozone, carbon monoxide, nitrogen oxides.
Currently, this phenomenon is of great importance, especially in areas with a warm climate. Next to Los Angeles, Mexico City is the second most smog-polluted metropolis.
Smog of this type is also common in Santiago, São Paulo, Caracas, Athens, Cairo, Tehran, Beijing, Shanghai, Bangkok and to a lesser extent Tokyo, Osaka, New York, Paris, Rome and Madrid.
Photochemical smogalso occurs in Polish cities where transport emissions are growing rapidly, especially as a result of a dynamic increase in passenger car journeys (e.g. Warsaw, Krakow).
Photochemical smog - how is it formed?
Photochemical smog is formed mainly in the summer months, during strong sunlight, mainly as a result of photochemical changes in exhaust gas components.
These reactions result in the formation of strong oxidants harmful to humans, animals and plants, such as ozone, formaldehyde, hydrogen peroxide, acetaldehyde.
Photochemical smog can occur from June / July to September / October at a temperature of 24-35 ° C, usually from noon to late afternoon. It reduces visibility to 0.8-1.6 km (the air has a brownish tint).
The sources of photochemical smog are:
- high emissions of photochemical oxidants precursors from the road transport sector and from municipal and household sources
- meteorological conditions:
- strong sunlight, - high temperature (above 25 degrees C) - "weak" wind (so-called silence) - temperature inversion
- terrain topography (depressions)
- coastal location (sea breezes) - an additional but not necessary condition for the formation of photochemical smog
Photochemical smog - impact on he alth
Photochemical smog leads to an increase in ozone levels in the air. In turn, increased ozone concentration in the air can lead to inflammatory reactions of the eyes or respiratory diseases, including the worsening of asthma symptoms and a reduction in lung efficiency.
The first symptoms of ozone irritation are coughing, a scratchy throat, headache, and drowsiness.
The human body defends itself against ozone entering the lungs and reduces the amount of oxygen inhaled, which in turn may aggravate cardiovascular diseases.
Ozone can cause drowsiness, headaches and fatigue, and a drop in blood pressure.
Long-term exposure to traffic pollution leads not only to disorders of the respiratory system, cardiovascular and nervous system diseases. The substances in the exhaust gas also have a detrimental effect on the development of the fetus.
Limits and Effects of Ozone Exposure
| Concentration μg / m3 | Ozone effects and limit values |
| 40 | noticeable smell |
| 100 | headache, eye irritation |
| 110 | respiratory tract irritation, decreased efficiency |
| 160 | inflammation of the airways |
| 180 | threshold value for informing the public about the risk of exceeding the permissible levels |
| 200 | breathing problems |
| 240 | alarm ozone concentration levels for the averaging period of one hour |
| 260 | possible asthma attacks |
>400 | reduced efficiency, permanent cell damage |
|
>1000 | chromosome damage |
|
in sensitive people, from the risk group.
Photochemical smog - who is particularly vulnerable? People at risk
People particularly exposed to the harmful effects of photochemical smog are:
- children (peopleadults breathe air in the amount of about 160 l / kg b.w., and children approx. 230 l / kg b.w.)
- people with asthma
- often outside buildings
- longer exposure with simultaneous intensive inhalation of air into the lungs - limited amount of oxygen absorbed, which makes breathing faster and shallower, and there is a problem with deep breathing
Photochemical vs sour smog
Sour smog, or London smog, occurs mainly from November to February in the temperate climate zone. Its cause is the so-called low emissions, i.e. heating houses with solid fuels, mainly coal.
In turn, photochemical smog (oxidizing smog) is formed mainly in the summer months. It usually hovers on sunny days, when the air temperature is high and the streets are busy.
Photochemical smog in Los Angeles
Source: Youtube.com/NowThis World