Hanoi winter: 40% of PM2.5 dust from local sources

Hanoi, the capital city of Vietnam, has been facing severe air pollution problems for years, especially during the winter season. According to our recent research, 40% of PM2.5 dust in the air during this time comes from local sources. This pollution not only affects the health of Hanoi’s residents but also has a negative impact on the city’s economy and environment.

The sources of PM2.5 dust in Hanoi are diverse, including transportation, industry, and construction activities. The city’s growing population and urbanization have led to an increase in traffic congestion and industrial activities, contributing to the air pollution problem.

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To tackle this issue, the local government has implemented various measures such as promoting public transportation, reducing emissions from factories, and controlling construction dust. However, more efforts are needed to address this urgent problem.

Difficulty in preventing dust pollution.

Although there have been a number of studies evaluating air pollution trends in Hanoi, there is a lack of information on the annual fluctuations in air pollution in the North in relation to changes in the winter monsoon. North.

Therefore, PhD Phung Ngoc Bao Anh (Institute of Human Geography, National, Science&Tech Academy of Social Sciences, and Laboratory of Atmospheric Physics and Chemistry University du Littoral Côte d’Opale France) and domestic partners , internationally wanted to understand trends in pollution emission sources, quantifying the contributions to local-long distance pollution as well as the mechanisms of pollution events in Hanoi. First of all, he and the research team want to answer the questions: what is the main regional source of aerosols in winter in East and Southeast Asia, and its trends throughout the period 2006 – 2020?; what sources actually affect northern National, Science&Tech through long-term transport, what influences the pollution contribution of the annual monsoon oscillation?; What is the contribution rate of different sources to air pollution on a daily scale in Hanoi?

A new way to approach the causes of dust pollution

According to researchers, Hanoi usually receives from 10 to 15 northeast monsoons from October this year to March next year, so the air quality in Hanoi as well as in the North of National, Science&Tech is affected by monsoons. The Northeast influences, creating cyclical changes in major gas transport routes and in meteorological conditions. They used a distinct approach to identify the main contributors to Hanoi’s air quality decline.

First, they used the US Naval Aerosol Analysis and Prediction (NAAPS) model with the HYSPLIT integrated orbital model to assimilate the aerosol optical thickness (AOD) observations. With the results obtained, they found that from the winter of 2006/2007 to the winter of 2010/2011, the highest AOD values were found throughout the Indochinese peninsula, mainly due to burning activities. biomass (natural and human). From winter 2011/2012 to winter 2019/2020, the pollution plumes were mainly in Eastern China and less so in Northern National, Science&Tech and the sulfate fraction in the AOD shows them from the activities of coal-using industries. make fuel.

Second, they used the HYSPLIT model to calculate the trajectories of air masses to determine distances, directions and air pollutants over 14 winters. During this period, air masses from Bong Bac overwhelmed, bringing pollution from East China and industrial areas around Hanoi into Hanoi. However, the existence of El Niño events disturbed the trajectories of air masses during the three winters (2014/2015, 2015/2016 and 2018/2019), bringing additional air masses from to the west and, therefore, lead to a decrease in AOD sulfate over time and a simultaneous increase in smog AOD throughout Hanoi.

Third, the researchers applied a method of classifying winter days and emphasized the effect of cold air on the variability of PM._2.5, mainly depends on local wind and AOD NAAPS values. This classification allowed them to estimate the long-term transport of dust from China during cold periods, which increased PM concentrations._2.5 30% in Hanoi during this period. In addition, local sources also contribute to pollution in the worst-case pollution scenarios, persisting during cold periods, estimated to account for up to 40% of PM dust concentrations._2.5.

Published research of Intricate behavior of winter pollution in Hanoi

The research results are clearly stated in the publication “Intricate behavior of winter pollution in Hanoi over the 2006–2020 semi-climatic period”. –2020), published in the magazine Atmospheric Environment.

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Air pollution is a serious problem in many cities around the world, and Hanoi is no exception. The publication “Intricate behavior of winter pollution in Hanoi over the 2006–2020 semi-climatic period” sheds light on the severity of the problem in the Vietnamese capital. This study was published in the magazine Atmospheric Environment in 2020, and provides detailed analysis of the sources and behavior of winter pollution in Hanoi over a 15-year period.

One of the key findings of the study is that 40% of PM2.5 dust in Hanoi during the winter months is from local sources. This is a significant proportion of the total pollution in the city, and highlights the need for action to reduce local sources of pollution. The study also found that the remaining 60% of PM2.5 dust in Hanoi during the winter months comes from outside the city, including from neighboring provinces and other countries.

The study also analyzed the behavior of pollution in Hanoi during the winter months. It found that there is a strong correlation between temperature and pollution levels. When the temperature drops, pollution levels in Hanoi tend to increase. This is due to a combination of factors, including increased use of heating and cooking appliances, as well as the tendency for pollution to become trapped in the city during cold weather.

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In addition to temperature, the study also looked at other factors that contribute to pollution levels in Hanoi. These include traffic, industrial activity, and agricultural burning. The study found that traffic is a significant source of pollution in the city, particularly during rush hour when the volume of vehicles on the road is highest. Industrial activity and agricultural burning were also found to contribute to pollution levels, although to a lesser extent than traffic.

The study concludes that reducing local sources of pollution is key to improving air quality in Hanoi during the winter months. This could include measures such as promoting the use of public transportation, encouraging the use of clean energy sources for heating and cooking, and enforcing regulations to reduce industrial and agricultural pollution. The study also highlights the importance of regional cooperation to address the issue of cross-border pollution, which contributes to a significant portion of the pollution in Hanoi during the winter months.

Previously, Phung Ngoc Bao Anh and colleagues published “Document details – Key factors explaining severe air pollution episodes in Hanoi during 2019 winter season” on Atmospheric Pollution Research, which explores the main factors impacting winter air pollution in the northeast monsoon conditions. Not only was he able to measure the atmospheric boundary layer during foggy days and cloudy days, but he also found that the atmospheric boundary layer is one of the main factors controlling air quality in Hanoi.

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