Air quality in Phetchaburi

How badly polluted is the air in Phetchaburi?

Phetchaburi is a state located in the central western region of Thailand, sitting in the Malay peninsula portion of Southeast Asia. It has the Gulf of Thailand facing it on its eastern coast, as well as Myanmar to the west, with their border divided by Tanaosi mountain range. It is home to one of the largest natural parks in the country, displaying that a good portion of its land mass consists of forested areas and nature reserves.

Whilst this would generally be a good aid in reducing the amount of air pollution in any given area, due to the beneficial effect that large areas of trees and plants have on the environment (as well as vast swathes of land being protected against further development), it still stands to reason that Phetchaburi seems to have some issues with its pollution levels, with its cities displaying some fairly prominent pollution levels, as well as certain months of the year that see drastic rises in their PM2.5 levels.

PM2.5 refers to particulate matter that is 2.5 micrometers or less in diameter, making it roughly 3% the size of a human hair, and due to the nature of its incredibly small size, very detrimental to human health when inhaled. Due to this property, as well as its ability to makes it way down to sizes as small as 0.001 microns across, it is a major component used in the calculation of a city, state or countries quality of air.

With high levels of PM2.5 in the atmosphere, there is a strong chance that the air is also contaminated with other pollutants that make up the overall AQI, or air quality index. These other pollutants include ones such as nitrogen dioxide (NO₂) and ozone (O₃).

Using the main city registered in the state of Phetchaburi as a good indicator to go off, Tha Yang will be used for reference in showing the average air quality in the state. Tha Yang came in with a PM2.5 reading of 24.2 μg/m³ over the course of 2019, a reading that put it into the ‘moderate’ pollution bracket, one that requires a PM2.5 reading of anywhere between 12.1 to 35.4 μg/m³ to be classified as such. This placed Tha Yang in 659^th place out of all cities registered worldwide, as well as 36^th place out of all cities registered in Thailand, coming in considerably ahead of the capital city of Bangkok, which had a PM2.5 reading of 22.8 μg/m³ and came in at 48^th place out of all cities ranked countrywide. This data is indicative that Phetchaburi is subject to some pollutive issues, with certain months of the year presenting a danger to the health of many members of its population.

What are the main causes of pollution in Phetchaburi?

Phetchaburi, like many other cities in Thailand and Southeast Asia, has multiple sources of pollution that come together to form the overall yearly average, with some sources raising the year round ambient readings and other sources causing more acute pollution spikes, seeing certain months of the year climb up considerably in their readings.

Looking at its economy, Phetchaburi has a significant role in salt production in Thailand, being one of its main producers and a large amount of its inhabitants working in this particular industry. Subsequently, when any given area is a large producer of a particular good, there is often the need to export it in large amounts, which requires the use of heavy duty vehicles for delivery. These vehicles often run on diesel fuels, and are sometimes not subject to the same stringent rules and regulations that are seen in other countries around the world. Due to this, there may be many of these larger vehicles running using significantly more aged motors, as well as using not only diesel but also lower quality fuels.

This can result in a significant amount of pollution being produced, with the aforementioned nitrogen dioxide being released in significant amounts, as well as other chemicals contaminants and fine particulate matter. Furthermore, production and packaging facilities can also add to the pollution levels, due to their use of coal and other unclean fuel sources to provide energy. This is not exclusive to just the salt industry however, with many other factories found across Phetchaburi that deal in the production of both electronic goods and industrial items, as well as food products.

So in short, Phetchaburi would see a large amount of its year round ambient pollution levels being pushed up by heavy duty vehicle use (as well as use of personal vehicles such as motorbikes and cars, both of which can also contribute significantly), and that of factory emissions. Another main cause of pollution would be from the burning of crop fields and areas of forest land, a practice known as slash and burn farming.

This practice releases massive amounts of toxic pollution and fine particulate matter into the air, and would be responsible for the more drastic spikes in PM2.5 witnessed in cities such as Tha Yang, although due to its seasonal nature, is thankfully not seen in every month of the year, although the open burning of wood, organic material as well as garbage and refuse still continues to happen in the more rural areas, another source that worsens the overall air quality.

When is pollution at its worst in Phetchaburi?

Observing the data taken in Tha Yang over the course of 2019, it becomes apparent when the air in Phetchaburi would be at its most permeated with haze, smog, smoke and other unwanted contaminants, with some of its PM2.5 readings coming in with significantly dangerous numbers.

This would remain fairly true for other cities in the state, with subtle variations and differences occurring due to smaller details of each individual city, but nevertheless they would all be subject to the same high and low pollution periods.

It is around September when the pollution levels start to take a turn for the worse, with the previous months reading of 7.8 μg/m³ in August rising very suddenly up to 18.2 μg/m³ in September, a reading that is more than double than the prior month. From here on out the pollution readings get even worse, with October coming in at 26.6 μg/m³ and then November and December showing the worst readings of the year, with PM2.5 numbers of 42.7 μg/m³ and 50.3 μg/m³ respectively, putting them into the ‘unhealthy for sensitive groups’ bracket.

This ratings bracket, as the name indicates, has some serious effects on the health of vulnerable portions of the population, with pregnant mothers, young children, the elderly and those with weakened immune systems or preexisting health conditions being the most at risk.

Although there is data missing at the beginning portion of the year, it can still be seen that the pollution levels remain high through to March and April, only showing signs of abating in May. March also came in at the ‘unhealthy for sensitive groups’ rating, which requires a PM2.5 reading of anywhere between 35.5 to 55.4 to be classified as such, with April dropping down to 24.7 μg/m³ and then 18.1 in May. This is indicative that from September or October through to May of the following year, the pollution levels would be at their worst in Tha Yang, and therefore Phetchaburi as a whole.

When is the air quality at its cleanest in Phetchaburi?

Leading on from the previous question, as mentioned the spikes in pollution and PM2.5 start to lower themselves significantly in the months of April through to June. The readings in order are 24.7 μg/m³ in April, followed by 18.1 μg/m³ and then 9.8 μg/m³ in June. This is a large reduction, with June coming in within the World Health Organizations target goal for the best quality of air at 10 μg/m³ or under, with the closest to 0 of course being the most optimal.

So, as the pollution levels drop to within safer and more appreciable numbers, it begins a phase of three months when the air quality is at its best, with June, July and August all coming in with the best readings, with 9.8 μg/m³, 10.1 μg/m³ and 7.8 μg/m³ all being recorded. This made August the cleanest month out of the year for Tha Yang, and by extension the state of Phetchaburi, although of note is that whilst there may be some variations in terms of numbers for other cities in Phetchaburi, this period of the year is when the air quality will be at its best.

What are some of the main pollutants found in the air in Phetchaburi?

As some of the main pollutants such as nitrogen dioxide and sulfur dioxide have already been touched on, there are a great number more that reside in the air during the more polluted months. Many of these would arise from the burning of crop fields, or organic matter as a whole when subject to combustion.

Black carbon, the main component in soot, as well as volatile organic compounds (VOC's) are released in large quantities both from vehicles that run on fossil fuels such as diesel (and so would be emitted from both personal vehicles and heavy duty ones), as well as the use of coal in factories and the more prominent burning of both refuse and organic matter. Black carbon is a particularly dangerous particulate matter, having both climate changing properties as well as carcinogenic ones when inhaled. Some examples of VOC's found in the air in Phetchaburi would be ones such as toluene, xylene, benzene, methylene chloride as well as formaldehyde.

These are all highly detrimental to human health, and are made even easier to respire due to their volatile nature making them gases, even at lower temperatures. Other pollutants emanating from combustion sources would be toxic metals such as lead, mercury and cadmium, alongside plastic fumes containing dioxins, furans and polychlorinated biphenyls.