'Strange smoke from Hanoi' is acid mist

' In the days of being covered by smoke, many Hanoi people find it difficult to breathe and sting. When light rain appeared, I measured and found that the pH of rainwater is quite low, only about 5.0-5.5. This result is synonymous with acid rain , 'said Dr. Nguyen Dinh Hoe.

Three weeks ago, mass media reported that Hanoi was flooded with ' strange smoke '. Representatives of the state management agency on the environment quickly blamed farmers in suburban areas for burning straw, causing smoke to enter the city center.

But environmental scientists don't think so simple. Dr. Nguyen Dinh Hoe, Faculty of Environment, Hanoi National University, said that when the phenomenon of haze occurs, Hanoi area has almost no wind, so the smoke from burning straw in the suburbs cannot fly into the city. .
' In the days of being covered by smoke, many Hanoi people find it difficult to breathe and sting. When light rain appeared, I measured and found that the pH of rainwater is quite low, only about 5.0-5.5. This result is synonymous with acid rain. Since then, I think that the smoke is not caused by burning straw but acid mist and environmentalists called photochemical smog, 'said Dr. Nguyen Dinh Hoe.

Acid mist is a very dangerous phenomenon of air pollution and it has happened several times in Hanoi in 2008. This is the result of air pollution due to motor vehicle emissions and smoke from vehicles. plant causes, combined with some unusual climate changes at some point.

Normally, the air layer temperature is from the ground to a height of about 150m hotter than the upper floor. As a result, emissions from vehicles and industrial production are quickly diffused by the wind into the air.

Acid mist is heavily covered in Van Quan area.(Photo: VNN)

However, in the days when Hanoi was attacked by smoke, the situation was the opposite. The upper air layer is hotter than the ground. Scientists call this 'the inverse effect' . The cool air is heavier, going is close to the ground pushing the hot air up high, causing convection to not happen. The air surface is stagnant, the pollutants accumulate with steam, creating acid mist. Smog is often very dense and when there is a smog there is no wind.

According to the 2007 national environmental report, air pollution in Vietnamese cities has become serious. This situation is similar in areas where industrial parks are concentrated. Monitoring results show that the amount of dust, lead and engine exhaust is rich in NO _x , SO _x , CO _x , benzene, toluene, xylene . in the air has increased 2-4 times in just two years.

This report suggests that the amount of waste in the air in Hanoi and Ho Chi Minh City may increase by 2-5 times in 2010. Types of engine and industrial emissions such as NO _x , SO _x , CO _x when combined with steam to form acid droplets, other toxic gases. These toxic dust gases attack the lungs through respiratory activity that causes lung pain, respiratory depression, headache, coma and possibly death.

Acid mist on the eyes also causes eye irritation, decreased vision. Trees withered leaves and can die like acid rain . According to Dr. Nguyen Dinh Hoe, acid mist and the effects of extreme temperatures are especially dangerous for the elderly, pregnant women, children and cardiovascular sufferers.

In Hanoi area, although the phenomenon of acid mist does not occur regularly, in the hot seasons, people often feel very uncomfortable, burning, although the temperature sometimes does not differ from other provinces. , southern city. Most likely, due to the high humidity in the air in the northern area, the steam associated with the exhaust creates acid mist, though not at a dense level but in the past few days, but enough Let everyone feel.

Acid mist is less felt in HCMC, but that does not mean that air pollution is better here than in Hanoi. The humidity of the air in the HCMC area is low, and there is plenty of wind to increase the diffusion of toxic emissions, so it is difficult to see acid mist with the naked eye. However, respiratory disease is quite common in children, the elderly, especially in the hot season, partly showing the severity of the air environment of the region.

Mr. Nguyen Dinh Hoe said: ' In fact, the air environment in the Southeast region has deteriorated very quickly. There may be less dense acid fog like Hanoi in the past few days, but acid rain here happens very often . ' According to the research results of environmental scientists, up to 60-70% of the annual rainfall in the Southeast is acid rain, higher than the Northern provinces.

In order to protect the environment and also protect the health of the community, the best solution is to control the emissions of air into the air environment by limiting the amount of traffic and improving treatment. exhaust fumes of industrial production facilities .

At the same time, the State should promulgate regulations to limit and prevent the use and import of equipment and means of transport with outdated technology and the ability to destroy large environments into Vietnam, such as regulations on the elimination of expired cars and motorcycles or the regulations on engine exhaust standards that Vietnam has been preparing to apply.

In addition, the State needs to invest heavily in monitoring, developing more automatic monitoring systems in urban areas and industrial zones, in order to give early warning about the air environment and have Solutions to overcome pollution when abnormal occurrence.