Air quality in Johor

Air quality index (AQI) and PM2.5 air pollution in Johor

Last update at (local time)


Real-time Johor
Most polluted city ranking

#cityUS AQI
1 Pasir Gudang


2 Tangkak


3 Johor Bahru


4 Segamat District


5 Kluang


6 Parit Sulong


7 Pengerang


8 Bandar Penawar


(local time)


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Department of Environment of Malaysia


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Real-time Johor
Cleanest city ranking

#cityUS AQI
1 Bandar Penawar


2 Pengerang


3 Parit Sulong


4 Kluang


5 Segamat District


6 Johor Bahru


7 Tangkak


8 Pasir Gudang


(local time)


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How bad are the pollution levels in Johor?

Johor is astate in peninsular Malaysia, located in the southernmost regions just aboveSingapore, with Indonesia also bordering very close by. As with many cities inMalaysia, it is subject to varying levels of pollution throughout the year,with some months being more prominent in their PM2.5 readings and others beingsignificantly cleaner.

The capitalcity of Johor state, Johor Bahru (new Johor) came in with a fairly decent PM2.5rating over the year of 2019, and due it being the capital as well as theeconomic hub, its data readings can be used to get a better idea of what theambient levels of pollution in the state are. PM2.5 refers to fine particulatematter that is 2.5 micrometers or less in diameter, making them approximately3% the size of a human hair. Due to this extremely small size, PM2.5 has ahighly negative effect on human health when inhaled, and as such is a veryimportant component used in calculating the overall air quality of a city, stateor country.

Back to JohorBahru's reading, in 2019 it came in at 16.8 μg/m³, putting it into the lowerend of the ‘moderate’ pollution bracket, which requires a reading of anywherebetween 12.1 to 35.4 μg/m³ to be classed as such. This places Johor's capitalcity at 1098th place out of all cities ranked worldwide, in terms oftheir pollution levels. Whilst there were some months that came in higher thanthe yearly average, this reading as mentioned is on the lower side of themoderate pollution spectrum, and with a reduction of only a few units, couldfind 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 atJohor'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 elevatedpollution levels, as are expected. This is due to the forest and farmland firesmaking their way over from Indonesia's Sumatran island portion and heavilyskewing the results of cities across Malaysia (as well as southern Thailand andSingapore). As such, the state of Johor finds itself with some fair pollutionissues, although not overly grievous in nature.

What are the main causes of pollution in Johor?

Statewide,there are numerous causes of pollution, with some having more prominence thanothers 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 numberof cars, motorbikes, trucks and buses dominating the roads all emit a varietyof pollutants, many of which contain chemicals or compounds that can linger inthe atmosphere and cause issues of elevated PM2.5 readings.

Besides thepollution levels caused by vehicles, there is also the industrial sector toconsider, with factories catering to furniture, food products and otherindustrial materials or chemicals being present, such as concrete or oilprocessing plants. These would also contribute to the yearly readings of PM2.5and PM10 readings (PM10 being particulate matter of 10 micrometers or less, thelarger 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 ofdangerous chemicals and pollutants, all of which will be discussed in moredetail.

In 2019 therewas a chemical disaster known as the Sungai Kim Kim incident in Pasir Gudang,which released large amounts of gases such as methyl mercaptan, acrylonitrileand acrolein into the air. whilst this did not have a significant effect on thereadings of PM2.5 in the air over the months the incident happened (withseveral separate incidents occurring), it did however have the effect of makingthe citizens of Johor pay much more attention to the pollution levels in thestate, and take notice of the negative side effects they can have on people,particularly young children, thus taking steps to ensure that pollution levelsare lowered in the future.

Of note isthat Johor is used as a transit hub to gain entry into Singapore via land. Assuch the vehicle numbers can be particularly high, with commuters and touristsmaking their way in and out of Singapore via Johor, along with trucks andlorries carrying their products for export. Many of these would still run onfossil fuels such as diesel, which can release considerably more pollution intothe air when compared to its cleaner fuel counterparts.

To recap, theindustrial sector, vehicle industry and the infamous Sumatran forest firesblowing over from Indonesia would all be responsible for raising the pollutionlevels in the state of Johor.

What are the main pollutants found in the air in Johor?

With vehiclesbeing a constant source of pollution, the gases being emitted from them wouldinclude ones such as nitrogen dioxide (NO2) and sulfur dioxide (SO­2),with nitrogen dioxide being the main culprit in vehicular emissions due to thelarge amounts released. It is so prominent in vehicle fumes that areas that seehigh levels of traffic will always see elevated levels of nitrogen dioxide inthe air. Because of this, it is somewhat of an efficient way to calculate howmuch of the air pollution is actually coming from vehicles, as a high readingof nitrogen dioxide will correlate heavily with a high volume of traffic, andvice versa. Although of note is that nitrogen dioxide finds itself beingreleased from several other sources, mainly those that see some sort ofcombustion taking place.

With bothfactories and certain vehicles running on fossil fuels, such as diesel in carsand coal for factories, a large amount of dangerous particulate matter would bereleased from these processes. Materials such as black carbon, volatile organiccompounds (VOC’s) and carbon monoxide (CO) would find their way into theatmosphere, with black carbon and VOC’s being formed through the incompletecombustion of organic matter as well as fossil fuels.

The forestfires of Sumatra would also carry in their smoke clouds these last twomentioned materials, along with other pollutants that arise from the burning ofplant matter. Chemical compounds such as benzene, toluene and xylene can findthemselves in the air, particularly when wood is burnt, as well as polynucleararomatic hydrocarbons. All of these have disastrous long term health effectswhen inhaled, as well as materials such as black carbon having climate alteringproperties due to its ability to absorb solar radiation and release it directlyas heat.

When is the air at its most polluted in Johor?

Going off ofthe readings taken over the various cities in Johor, it is clear and alsopredictable that September is the worst month, due to the smog and haze makingits way over from the Sumatran region of Indonesia. The farmers continue topractice 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 toMalaysia, as well as affecting southern Thailand and Singapore.

Observing themeasurement of PM2.5 levels, the city of Tangkak came in at 42.4 μg/m³ inSeptember 2019, and Segamat district with a reading of 36 μg/m³. These numbersboth fall into the ‘unhealthy for sensitive groups’ bracket, which requires aPM2.5 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 torespiratory illnesses, as well as being a hazard to young children, the elderlyand pregnant mothers.

On the otherside, the cleanest months seen in Johor are December through to February of thenext 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 ofthe eight cities ranked in Johor state came in with months that fell into theWHO’s target bracket, showing that whilst there are pollution issues stillaffecting the state, there are months that see very good qualities of air, withthe monsoon season being mostly responsible due to the highly cleansing effectthat rain has on air quality, removing large amounts of particulate matter andother built-up pollutants.

What are some health problems associated with pollution in Johor?

With certaincities coming in with readings as high as 42.4 μg/m³ and 36 μg/m³, there wouldbe elevated risks for adverse health symptoms appearing. These would includeailments such as chest infections, aggravated asthma, as well as higher chancesof developing respiratory diseases such as bronchitis and emphysema.

Due to theincredibly small size of PM2.5, any pollutant that finds itself in this sizebracket can penetrate deep into the lung tissue, where it can raise incidencesof lung cancer, reduce overall lung function, and in some cases actually crossover into the circulatory system via the alveoli in the lungs. Once it is inthe blood stream, it can cause a myriad of problems such as damage to the bloodvessels, arrythmias and increased chances of heart attacks occurring. As such,during these worse months of pollution, preventative measures such as avoidingoutdoor activities or the wearing of high-quality particle filtering masks would go a long way inreducing the negative health effects of pollution exposure.

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