Qualité de l’air à Da Lat

How polluted is the air in Da Lat?

Da Lat is a city in the south east region of Vietnam, with a notable trait of having a high altitude, being some 1500 meters above sea level. Due to this geographical trait, Da Lat is subject to having a wide variety of weather conditions, being far more temperate than many other cities located around Vietnam. Well known for its natural beauty and being a popular tourist destination, Da Lat is also a city that has a very good quality of air, with US AQI readings taken in late 2020 coming in consistently with good ratings, as well as the concentration of PM2.5 in the air being recorded with levels as low as 4.1 µg/m³, up to a maximum of 8.1 µg/m³, both of which are well within the World Health Organizations (WHO’s) target goal of 0 to 10 µg/m³ in regards to fine particulate matter found in the air. This makes Da Lat a very clean city, with large amounts of trees and forested areas surrounding it as well as its high position above sea level all contributing to its cleaner quality of air.

There are however a few issues that are known to cause elevated levels of pollution in Da Lat, such as the high volume of tourism, both local and domestic, as well as the agricultural industry. Da Lat’s economy is mainly driven by the production and growth of vegetables and other similar produce that can only be grown in temperate climates, giving the city a unique agricultural standing amongst the whole of the country. With a high output of such produce, there will naturally be an elevated level of pollution produced from this sector, with an increase in demand meaning and increase in farms and factories to cater to the growth and packaging or containment of these goods. Traditionally in times past, farming did not have any adverse effect on pollution levels, unless of course slash and burn farming methods are used, whereby crop stubble and forested areas are set ablaze in order to create more room for plantation, as well as returning nutrients to the soil. However, to return the topic of farming, as mentioned that on a small and traditional scale there are little environmental effects, however once the produce reaches a country wide and international demand, the size of the agricultural industry can grow to the point that it has adverse effects on the environment, with the removal of large areas of forest and introduction of more production plants and factories all causing heightened readings of pollution in the air.

As well as the pollution caused by the tourism industry (with a notable decline in 2020 due to the COVID-19 outbreak), Da Lat is known to suffer from large accumulations of garbage and waste left strewn around its city limits, both from the irresponsible disposal of waste coming mainly from tourists. These large sites of garbage and refuse have in the past caught on fire and released high amounts of smoke and haze into the atmosphere, contributing to the pollution levels. However, these are not events that happen consistently, and as it stands, Da Lat has air quality of a considerably good standard year-round.

What are the main causes of pollution in Da Lat?

As mentioned previously, the main causes of pollution in Da Lat are the agricultural and tourist industries, with the tourist industry bringing with it a higher number of transit vehicles. As such, during peak seasons of tourist activity, there will be elevated levels of primary and secondary pollutants found in the air, particularly ones such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂), with nitrogen dioxide being one of particular importance, due to its high emission from cars, buses and trucks. Levels of nitrogen dioxide in the air can be used to directly correlate how much traffic or vehicular activity is taking place in any given region, as it has been consistently shown that where there are high levels of nitrogen dioxide present, there will be a high volume of vehicles passing through that area, and vice versa.

With an increase in the aforementioned international demand for Da Lats agricultural produce, it is a natural evolution that there will be ever more vehicles (particularly trucks, which in these regions often run on diesel based fuels which in turn contribute more to pollution levels in the air) ferrying the produce out of the city and to neighboring locations where it is prepared and made ready for international distribution. To compound this, larger areas of forest and greenery will be cleared to make room for more farmland, putting a dent into Da Lats natural defense against the accumulation of pollution and a reduction in air quality.

Another main cause that has direct links with vehicle usage similar to the transportation of goods, is the transportation of people who are there for touristic reasons. This in turn leads to a further build up of PM2.5 to be found in the air, and in particular chemical compounds such as the aforementioned nitrogen dioxide. On a closing note, the garbage can indirectly contribute to the level of air pollution, with many recorded instances of these heaps catching fire, which would undoubtedly lead to huge increases in levels of smoke and haze, although due to Da Lats natural defenses such as high elevation and cool temperature, these clouds of smoke resulting from the occasional fires would not linger in the atmosphere for too long, as cities with low elevation often suffer from.

What is being done about the air quality in Da Lat?

In the few years preceding 2020, it has become apparent that the refuse heaps and garbage found littering the city have become of increasing concern to its citizens. As such, many initiatives such as the education of tourists on proper environmental behaviors is being implemented, due to many areas of natural beauty being spoiled by the huge heaps of garbage, which during dry season presents an ever-increased risks of catching fire and having disastrous effects on those breathing the polluted air. It is also of note that there is a current lack of efficient garbage collection systems, as well as there being a lack of simple garbage reduction facilities such as basic waste disposal bins. With initiatives to increase the efficiency of refuse collection as well as cracking down on offenders, Da Lat can go a long way in terms of reducing the risk of garbage fires and improving the quality of its air.

What are the health effects of breathing polluted air in Da Lat?

As mentioned before, Da Lat has an extremely good quality of air, and as such its citizens would not suffer any particularly negative effects. However, when the fires do occur, health effects of inhaling such pollution would include irritation to the eyes, nose, throat and skin, as well as increased risks of triggering conditions such as asthma and bronchitis. Prolonged breathing of smoke and haze in the air can cause even more negative symptoms to arise, such as decreased lung function, lower life expectancy as well as an increase in ailments such as lung cancer and heart diseases. As mentioned previously, this would only be of concern during the short-lived periods of garbage fires that occasionally occur throughout the year.

How does the quality of air in Da Lat compare to other cities in Vietnam?

When compared to a major city in Vietnam such as Hanoi, one can observe significant differences in the quality of air. Hanoi came in the a PM2.5 average yearly reading of 46.9 µg/m³ over 2019, putting it in the unhealthy for sensitive groups bracket, with some months even going straight into the ‘unhealthy’ category, which requires a pm2.5 reading between 55.5 to 150.4 µg/m³ to achieve. When the data in 2020 is observed, it can be seen that late in the year Hanoi is still giving PM2.5 readings of up to 65 µg/m³, putting it once again into the unhealthy bracket. Da Lat in comparison is coming in with PM2.5 readings of around 6.1 µg/m³, showing that the air in Da Lat is cleaner by a significant amount, and has similar stories when compared to a number of other cities around Vietnam. To close, Da Lat has air quality that is of an extremely good standard.