Air Quality

The Environmental Performance Index (EPI) ranks Vietnam as one of the 10 worst countries for air quality. Is this assessment correct? And how does Hanoi fare when it comes to the city’s air? Words by Katie Jacobs, photos by Thiep Nguyen


In February of this year Word ran an article on indoor and outdoor air quality in Ho Chi Minh City. Using a ParticleScan Pro, a handheld laser particle counter, the pollution levels were tested at various locations around the city. The ParticleScan Pro measures the number of fine particles in one litre of air. According to the World Health Organization (WHO), this should not exceed 60,000. Results weren’t good. In some parts of the city, outdoor readings were more than five times the safe recommended level. Yet after the rain just in front of Ben Thanh Market, one of the city’s busiest junctions, they were around 55,000. So with a growing population and forever increasing numbers of cars, trucks, buses and motorcycles, how does Hanoi compare to its southern counterpart?

Tho Xuong by the cathedral

On the Street

On a grey July morning we arrived on the banks of Tay Ho, particle scanner in hand. The air was muggy, the sky overcast, and as the scanner buzzed to life, the illuminated numbers on the screen began to climb rapidly, coming to rest at 230,000. The air in this part of Hanoi, reputed to be the cleanest in the city, was nearly four times the recommended limit. Over the next six days, measurements were taken at nine outdoor and five indoor locations around the city. Results fluctuated from the comfortingly low to alarmingly high.

Traffic is not the only danger on the streets of Hanoi; air pollution is posing a serious threat to the health of the city. Although not physically visible like traffic accidents, damage caused by air pollution is nothing to sneeze at. According to WHO, more than two million people die around the world annually as a result of air pollutants, with nearly 7,000 of those deaths in Vietnam. Air pollution affects cities globally, but WHO analysis suggests that people in middle-income countries, such as Vietnam, are most at risk. As the country becomes wealthier, more people ride motorcycles and drive cars. Records show that between 1996 and 2006, the number of motorcycles in Vietnam increased by 400 percent, sending air pollution rates soaring.

Studies by the US-based Centers for Disease Control and Prevention (CDC) have linked poor air quality to a variety of serious and often fatal diseases. Of the complex mix of air pollutants emitted daily from industry, households and transport, it is the fine particulate matter (PM) that is most harmful to human health. The CDC warns that particles less than 10 micrometres, known as PM10, penetrate into the body and settle in the lungs and bronchi. Cancer, heart attacks, asthma, cardiovascular disease and impaired foetal development are just a few of the ailments associated with air pollution. Many of these side effects cannot be cured and require lifetime medical attention. The Vietnamese Labour Health and Environmental Hygiene Institute estimates that the annual health-related costs of air pollution are as high as US$20 million (VND4.2 trillion) in Hanoi alone.

Ho Hoan Kiem

The Results

Back at Tay Ho, the air and our understanding were becoming clearer. As the day wore on, measurements around the city began to fall. Even on the side of busy roads readings hovered around 130,000; dropping to below 100,000 in quiet areas. Given the earlier readings, this was surprising. Then we stopped focusing on the traffic and turned our attention upwards. A breeze had picked up throughout the day and the grey sky of the morning now revealed sunshine. As the weather cleared, so too did the smog and pollution. This pattern was repeated throughout our study with overcast weather resulting in lower air quality. In the next two hours, the particle count ranged from 85,000 in sunshine to 380,000 as the breeze dropped and the sky turned grey. Meteorological analysis by the National Aeronautics and Space Administration (NASA) confirms this phenomenon; cloud cover not only prevents warm air from rising, it also traps pollution close to the earth’s surface. This is exacerbated when there is no air movement to disperse particles. However, even when the sun was shining, only one of our recordings fell within WHO air quality guidelines. Even on a good day, Hanoi’s air quality is poor.

Pho Restaurant

The Indoor Effect

In a bustling alley in the old quarter the scanner settled on 100,000, a relatively clean reading. Next door, a cigarette was lit and the figures began to jump, peaking at 230,000. The cigarette had more than doubled the pollution. If this was the effect of one cigarette outdoors, what would happen indoors in a smoky atmosphere? Seated in a nearby, fan-cooled cafe, figures settled at around 480,000. Over the next half hour this fluctuated greatly. With the ceiling fan on the readings dropped to around 300,000, but when a cigarette was lit they skyrocketed to well over a million. Readings at other restaurants reflected this trend. It became obvious that not only are cigarettes disastrous to air quality, but air movement — from open windows, fans and air conditioners — has a significant effect on clearing the air.

According to the CDC, the health effects of indoor air pollution, usually caused by cooking and cigarettes, are similar to that from outdoor pollution. However, the intensity and frequency of these effects are amplified indoors where pollution becomes trapped in a closed environment. Emissions from polluting cooking sources are declining in Hanoi, but harm caused from the inhalation of secondhand smoke is a serious concern. Hanoi is filled with cigarette smoke, putting non-smokers and particularly children at serious risk of diseases such as pneumonia, bronchitis and lung cancer. The US Environmental Protection Agency cites ventilation as the key to reducing indoor air pollution. Air movement and an adequate supply of outside air, even Hanoi’s polluted air, is essential for diluting indoor air pollutants.


Hanoi vs. Ho Chi Minh City

With data in hand, the verdict on which city has the best air was in. So how does Hanoi compare to its sister metropolis down south? The measurements were only taken during a six-day window — over a longer time period they could be different, meaning there is margin for error. But Hanoi showed itself to be slightly worse. With an average reading of 160,000 compared with the 140,000 recorded in Ho Chi Minh City, Hanoi recorded a lower quality of air. Although the scope is limited, it offers an interesting comparison, in particular to cities like Beijing, which records an average air quality of 1.5 million. If you think Hanoi is bad, try heading to that colossal country further north.

Bayan Cafe

The Readings


There are two accepted methods for reading air quality. The first measures the weight of fine dust, while the second, which we used for this article, measures the approximate number of fine dust particles per litre of air. The comparisons are as follows — the weight measurements are in italics:


0 μg/m3 to 9.9 μg/m3
0 — 30,000

10 μg/m3 to 19.9μg/m3
30,001 — 60,000

20 μg/m3 to 34.9 μg / m3
60,001 — 105,000

35 μg/m3 to 49.9 μg / m3
105,001 — 150,000

50 μg/m3 to 99.9 μg / m3
150,001 — 300, 000

100 μg/m3 and higher
300,001 +


Taking Action

Air pollution affects everyone and unless action is taken to curb emissions, Hanoi’s air quality will only deteriorate further. To follow are actions that individuals can take to help reduce air pollution and protect their health.


— On short trips, reconsider your need to drive a scooter and encourage bike and car sharing to reduce the number of motorcycles on the road

— Choose motorcycles that are clean and fuel efficient. Even better, use bicycles or electric bicycles

— If you’re on a motorcycle remember to turn off the engine if you’re stopped for more than 20 seconds

— Always wear a facemask on the street

— Never smoke indoors, especially around children, who are vulnerable to secondhand smoke

— Keep your house and office well ventilated by turning on fans and opening windows


To lower the effects of indoor air pollution, if you can stretch your budget, buy an air purifier. The Swiss-built IQAir machines can be purchased in Vietnam through their official distributor. Go to for more information.


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