Johor is a state in peninsular Malaysia, located in the southernmost regions just above Singapore, with Indonesia also bordering very close by. As with many cities in Malaysia, it is subject to varying levels of pollution throughout the year, with some months being more prominent in their PM2.5 readings and others being significantly cleaner.
The capital city of Johor state, Johor Bahru (new Johor) came in with a fairly decent PM2.5 rating over the year of 2019, and due it being the capital as well as the economic hub, its data readings can be used to get a better idea of what the ambient levels of pollution in the state are. PM2.5 refers to fine particulate matter that is 2.5 micrometers or less in diameter, making them approximately 3% the size of a human hair. Due to this extremely small size, PM2.5 has a highly negative effect on human health when inhaled, and as such is a very important component used in calculating the overall air quality of a city, state or country.
Back to Johor Bahru's reading, in 2019 it came in at 16.8 μg/m³, putting it into the lower end of the ‘moderate’ pollution bracket, which requires a reading of anywhere between 12.1 to 35.4 μg/m³ to be classed as such. This places Johor's capital city at 1098th place out of all cities ranked worldwide, in terms of their pollution levels. Whilst there were some months that came in higher than the yearly average, this reading as mentioned is on the lower side of the moderate pollution spectrum, and with a reduction of only a few units, could find its way into a lower rating bracket, the next one down being a ‘good’ level of pollution which requires readings of 10 to 12 μg/m³ to be classed.
Looking at Johor's most polluted city in 2019, Tangkak, it came in with a reading of 18.6 μg/m³, not significantly above that of the capitals, but with some months of elevated pollution levels, as are expected. This is due to the forest and farmland fires making their way over from Indonesia's Sumatran island portion and heavily skewing the results of cities across Malaysia (as well as southern Thailand and Singapore). As such, the state of Johor finds itself with some fair pollution issues, although not overly grievous in nature.
Statewide, there are numerous causes of pollution, with some having more prominence than others and having various effects on the PM2.5 readings throughout the year. One source of pollution that raises the ambient levels of pollution in Johor, as well as all cities worldwide, is emissions from vehicles. The large number of cars, motorbikes, trucks and buses dominating the roads all emit a variety of pollutants, many of which contain chemicals or compounds that can linger in the atmosphere and cause issues of elevated PM2.5 readings.
Besides the pollution levels caused by vehicles, there is also the industrial sector to consider, with factories catering to furniture, food products and other industrial materials or chemicals being present, such as concrete or oil processing plants. These would also contribute to the yearly readings of PM2.5 and PM10 readings (PM10 being particulate matter of 10 micrometers or less, the larger cousin of PM2.5 and somewhat less dangerous due to its larger size). Factories often run on fossil fuels such as coal, which gives off a variety of dangerous chemicals and pollutants, all of which will be discussed in more detail.
In 2019 there was a chemical disaster known as the Sungai Kim Kim incident in Pasir Gudang, which released large amounts of gases such as methyl mercaptan, acrylonitrile and acrolein into the air. whilst this did not have a significant effect on the readings of PM2.5 in the air over the months the incident happened (with several separate incidents occurring), it did however have the effect of making the citizens of Johor pay much more attention to the pollution levels in the state, and take notice of the negative side effects they can have on people, particularly young children, thus taking steps to ensure that pollution levels are lowered in the future.
Of note is that Johor is used as a transit hub to gain entry into Singapore via land. As such the vehicle numbers can be particularly high, with commuters and tourists making their way in and out of Singapore via Johor, along with trucks and lorries carrying their products for export. Many of these would still run on fossil fuels such as diesel, which can release considerably more pollution into the air when compared to its cleaner fuel counterparts.
To recap, the industrial sector, vehicle industry and the infamous Sumatran forest fires blowing over from Indonesia would all be responsible for raising the pollution levels in the state of Johor.
With vehicles being a constant source of pollution, the gases being emitted from them would include ones such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), with nitrogen dioxide being the main culprit in vehicular emissions due to the large amounts released. It is so prominent in vehicle fumes that areas that see high levels of traffic will always see elevated levels of nitrogen dioxide in the air. Because of this, it is somewhat of an efficient way to calculate how much of the air pollution is actually coming from vehicles, as a high reading of nitrogen dioxide will correlate heavily with a high volume of traffic, and vice versa. Although of note is that nitrogen dioxide finds itself being released from several other sources, mainly those that see some sort of combustion taking place.
With both factories and certain vehicles running on fossil fuels, such as diesel in cars and coal for factories, a large amount of dangerous particulate matter would be released from these processes. Materials such as black carbon, volatile organic compounds (VOC’s) and carbon monoxide (CO) would find their way into the atmosphere, with black carbon and VOC’s being formed through the incomplete combustion of organic matter as well as fossil fuels.
The forest fires of Sumatra would also carry in their smoke clouds these last two mentioned materials, along with other pollutants that arise from the burning of plant matter. Chemical compounds such as benzene, toluene and xylene can find themselves in the air, particularly when wood is burnt, as well as polynuclear aromatic hydrocarbons. All of these have disastrous long term health effects when inhaled, as well as materials such as black carbon having climate altering properties due to its ability to absorb solar radiation and release it directly as heat.
Going off of the readings taken over the various cities in Johor, it is clear and also predictable that September is the worst month, due to the smog and haze making its way over from the Sumatran region of Indonesia. The farmers continue to practice a method of ‘slash and burn’ farming, despite it being highly illegal, and strong winds blow these huge clouds of smoke and pollution directly over to Malaysia, as well as affecting southern Thailand and Singapore.
Observing the measurement of PM2.5 levels, the city of Tangkak came in at 42.4 μg/m³ in September 2019, and Segamat district with a reading of 36 μg/m³. These numbers both fall into the ‘unhealthy for sensitive groups’ bracket, which requires a PM2.5 reading of anywhere between 35.5 to 55.4 μg/m³ to be classed as such. This would make the air quality dangerous for those who are susceptible to respiratory illnesses, as well as being a hazard to young children, the elderly and pregnant mothers.
On the other side, the cleanest months seen in Johor are December through to February of the next year, with nearly every city seeing numbers that put them into the ‘good’ ratings bracket (10 to 12 μg/m³) or the coveted World Health Organizations (WHO) target reading of 0 to 10 μg/m³.
Six out of the eight cities ranked in Johor state came in with months that fell into the WHO’s target bracket, showing that whilst there are pollution issues still affecting the state, there are months that see very good qualities of air, with the monsoon season being mostly responsible due to the highly cleansing effect that rain has on air quality, removing large amounts of particulate matter and other built-up pollutants.
With certain cities coming in with readings as high as 42.4 μg/m³ and 36 μg/m³, there would be elevated risks for adverse health symptoms appearing. These would include ailments such as chest infections, aggravated asthma, as well as higher chances of developing respiratory diseases such as bronchitis and emphysema.
Due to the incredibly small size of PM2.5, any pollutant that finds itself in this size bracket can penetrate deep into the lung tissue, where it can raise incidences of lung cancer, reduce overall lung function, and in some cases actually cross over into the circulatory system via the alveoli in the lungs. Once it is in the blood stream, it can cause a myriad of problems such as damage to the blood vessels, arrythmias and increased chances of heart attacks occurring. As such, during these worse months of pollution, preventative measures such as avoiding outdoor activities or the wearing of high-quality particle filtering masks would go a long way in reducing the negative health effects of pollution exposure.