Bad in the Dry Season, but not even Great in the Rains: Yangon Air Quality over the Year

Air pollution from small particulate matter leads to serious health risks. A review of one year of air quality data collected by hbs Yangon shows that air quality in Myanmar’s commercial capital is hardly ever “good”, and it is especially bad in the winter months and until May.

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Air pollution from small particulate matter leads to serious health risks, worsening pre-existing respiratory conditions, particularly asthma, and increasing the risk for many other diseases. In Yangon especially, public worry about air pollution has been growing in recent years. Anyone living in Yangon must have noticed haze and smoke, and much-reduced visibility, primarily in the morning of the winter months.

Various institutions in Yangon (government as well as research institutions) reportedly have been collecting air quality data for Yangon over some years. However, this data has not been published. Publicly available reporting on air quality began only by late 2018, when various actors – including the Yangon office of the Heinrich Böll Stiftung (hbs) – started to operate their own air quality monitoring devices and published the data in real-time through their websites and dedicated smartphone apps (for details see below).

One Year of Air Quality and Air Pollution

Air quality is measured by the “air quality index” (AQI) constructed from measurements of particulate matter smaller than 2.5 micrometers (“pm 2.5”). It is grouped into a scale and color scheme from “good” through “unhealthy” to “hazardous” based on internationally accepted and standardized public health criteria.

Air Quality Index and Color Scale

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The data collected by hbs since January 2019 is shown in two graphs here, depicting daily and monthly averages (with a few interruptions as a result of technical problems).

Yangon AQI: Daily Averages

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The data shows that Yangon air quality rarely ever qualifies as “good” (AQI 50 or below) – except directly after downpours in the rainy season. Throughout 2019, Yangon experienced only 36 days where the air quality qualified as “good” – most of these where in the rainy season between June and mid-September, plus a few days in November.

Judging from this, in terms of air quality, the most favorable months for outdoor sports in Yangon would be June, July and August – if not for the prevailing heat and humidity at that time of the year.

Yangon AQI: Monthly Averages

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Technically, for about half a year, Yangon air quality fell into the “moderate” category (AQI between 51 and 100) – but with a clear decline from the last week of September onwards. “Moderate” air quality, from a public health perspective, does not mean a particular risk for healthy adults. However, it may have negative impacts on children and people with particular sensitivity (e.g., asthma) especially when exercising outside.

Also, the annual average AQI for Yangon is at about 90 and thus still “moderate” – but only just so. And like every average, it hides a considerable variation.

Unhealthy Air Conditions in the Cold and Hot Seasons

During the entire first five months’ period of the year – from January to May 2019, and again since January 2020 – air quality has to be categorized as “unhealthy for sensitive groups” (with a monthly average AQI exceeding 100). This was the time of visible haze and smoke to be smelled regularly – a period of clear negative health impacts for parts of the population.

And it got worse: During the first four months of 2019, we measured 13 days were the daily AQI averages reached a level beyond 150 – a level classified as “unhealthy” for everybody. It is in those days that Yangon’s air is often worse than the famously polluted air of Bangkok, when people in Yangon publicly worry, and when air purifiers are sold out in the city.

Measurements taken during the first few weeks of the new year 2020 indicate that now, the problem is at least as bad as it was in 2019. It may become worse if the trend currently visible for February continues – and by May we will know how bad the season turns out to be.

Changes during the Day

Air quality in Yangon does not only change over the course of the year, but it also varies considerably during the day – every day. Two graphs shown below depict air quality during typical days of the month (created by calculating an average over the respective month), for February at the height of the cold season pollution, and for June, as a rainy season example.

AQI during the Day: Dry Season vs. Rainy Season

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A basic pattern is easily recognizable, and it can be seen virtually every day: Pollution is usually at its lowest during noon-time and in the early afternoon; it increases afterward and during the night, peaking in the early morning hours, before decreasing again until noon. This pattern is most clearly visible in the winter but also remains recognizable during the rainy season, though on a lower level.

This, of course, is bad news for everyone who intends to do outdoor exercises in the cooler morning hours – in fact, from an air pollution perspective, this is the worst time of the day – every day.

Where does this pattern come from? The accumulation of pollutants overnight and their peaks in the early morning hours is most likely due to the fact that there is little vertical circulation of air in the city overnight. But once the sun comes out and warms the ground, the warmed air above it rises, thus dissolving the accumulated pollutants. The cycle begins again in the afternoon, as dusk begins and sunshine levels are lower.

Where does Yangon Air Pollution come from?

The fall of pollution levels, following their peaks in the morning, start later during the cold season than in the rainy season. This indicates that the daily cycle is linked to daylight and sunshine patterns. It also means that the impact of human activity (morning cooking and traffic) on the variation over the day is likely to be rather limited.

The graph for June, depicted above, also shows that a noticeable basic air pollution level is present nearly all day even during the rainy season. This AQI of around 60 (or perhaps somewhat more, as the annual AQI average amounts to 90) could be referred to as the “baseload” air pollution in Yangon. It is the result of a combination of factors common in urban life: emissions from traffic, industry, construction etc.

On top of that “baseload”, and seriously so, comes extra pollution during the dry season, in the cold and hot periods. Agricultural practices such as the burning of fields – common all over Southeast Asia – as well as waste- and plant-residue-burning in the city (both primarily dry season phenomena) are the most likely candidates for the dry season “extra load”.

What is to be done?

Yangon air pollution has reached levels of health concern – especially in the dry season which makes for the larger part of the year, and most markedly in the cold months. What can be done about it?

On an individual level, air purifiers for inside use and (to some extent) face masks for use outside will reduce exposure and thus limit the resulting health risks. But this is only a partial solution for those who can afford such devices and are not forced to regularly do heavy work outside.

Authorities in Yangon clearly could address some of the “baseload” pollution: by encouraging the use of public transport and bicycles, rather than expanding motorized traffic; by forcing heavily polluting industries (e.g. those that use coal-fired boilers for process heat) to install better filters or move to other energy sources.

In order to address dry season pollution, the city of Yangon should not just prohibit the widespread burning of waste and plant residue; it actually needs to enforce such prohibitions. On a larger scale, agricultural practices – especially the regular burning of fields – need to be addressed as one of the major causes of air pollution in the entire season.

Finally, more research is needed. Air quality monitoring devices should be put up outside of Yangon. They will document the extent of air quality issues throughout the country, but they will also be useful to identify the role of Yangon-specific factors (the “baseload” pollution mentioned above). Deeper scientific studies looking at particular sources of pollution and their role in the overall “pollution mix” could help to bring about focused policy interventions.


Further Information

hbs Air Quality Monitor - Technical Aspects: hbs Yangon operates an Air Quality Monitor made by Airveda. The device is fixed outside our office at the Kamaryut/Hlaing boundary (off Kan Street). Based on measurements taken every minute, the device delivers value averaged over the last 30 minutes. Real-time monitoring data are made available online at the hbs Yangon website and on the worldwide map on the Airveda website, (also available as an Android App). Due to technical problems, the usable data start only from January 15, 2019, and 6 and 11 days of data are missing in October and November, respectively.

The monitor used is a consumer quality device. To our knowledge, the only monitor with “research quality” credentials in Myanmar producing public data is the one that is operated since May 2019 by the U.S. Embassy in Yangon 2019, see below. However, the data provided by hbs’ device, when compared to other ones available, are comparable and consistent enough to clearly show the main problems and trends. (hbs is happy to make the entire dataset available on request – if interested, please send an email to info@mm.boell.org.)

Other publicly-available data sources: A group of non-governmental actors and public science enthusiasts in Yangon including a group of students of Connect University around Kirt Page have set up a number of “Purple Air” devices in different parts of Yangon. Their data are available online.

The U.S. Embassy in Yangon operates a monitor since May 2019.