Air quality and haze in Semarang

What are the pollution levels in Semarang?

The city of Semarang is located in central Java, being the capital as well as the largest city in the province. It has a population of some 1.5 million people living there (as of 2010), and as such suffers from increased levels of pollution due to human activity.

With a large population often comes a large number of cars and other personal vehicles such as motorbikes, along with factories and industries to support a growing city. In recent times, pollution levels in Semarang have come in with a fairly wide variety of readings, with highs of 44.6 μg/m³ being recorded in late November of 2020, and lows of 13.6 μg/m³ being recorded in early December, showing some differences in pollution levels that fluctuate on a daily basis.

This high reading of 44.6 μg/m³ would put Semarang (on that particular day) into the ‘unhealthy for sensitive groups’ rating. As the name implies, portions of the population with a predisposition towards being affected by chemicals would be at risk due to the pollution levels, with groups such as the young, elderly, pregnant mothers and immunocompromised all being at increased risk. The lower readings do show respite in the forms of days that fall within the World Health Organizations (WHO) target goal of 0 to 10 μg/m³ of PM2.5, but these are lesser in number and as such the average tends towards the higher end of the spectrum, making pollution in Semarang a topic that needs addressing.

What are the causes of air pollution in Semarang?

When observing the causes behind pollution in much of Indonesia, and in particular Semarang, the majority of ground-based pollution tends to find itself emanating from vehicular sources, as well as from industrial ones such as factories or other production facilities (more often than not powered by fossil fuel sources such as coal and gas).

During rush hour times, pollution levels can rapidly rise to unhealthy levels, and due to the topography of Semarang's urban landscape, may have a hard time dispersing, particularly in months that see less amounts of rain or wind, both of which are vital natural elements in the reduction of pollution. Cars, motorbikes and lorries can all give out large amounts of smoke and haze, with secondary pollutants such as nitrogen dioxide (NO₂) dominating the emissions.

Secondary pollutants are ones that arise from chemical reactions taking place in the atmosphere between primary pollutants, which in turn find themselves (the primary pollutants) coming directly from a source such as a fire or combustion of fuel. These primary pollutants make their way into the atmosphere in the form of gases or fine particulate matter (PM2.5 or PM10) and bond which each other chemically, forming more dangerous compounds such as sulfur dioxide (SO₂) and ozone (O₃).

Of importance is the fact that certain pollutants such as nitrogen dioxide may be counted as both primary and secondary pollutants, due to its ability to be released directly from a combustion source such as industrial machinery or a car engine, or form later on in the atmosphere as a secondary pollutant from the chemical reactions taking place between the nitrogen oxides (NOx). To close, the main pollution sources are vehicles as well as factory-based emissions, with vehicles being the dominating factor in pollution in Semarang.

What are some health risks associated with polluted air in Semarang?

When people are exposed over both long and short periods of time to PM2.5, PM10 along with other dangerous gases as mentioned before, many symptoms can present themselves. In the short term, instances of irritation to the skin, eyes, nose and airways may become apparent, as well as risks of chest infections and overall reduction in lung function, leading to higher rates of mortality amongst adults as well as having negative consequences on the growth of young children.

Exposure to materials such as burnt plastic fumes (as would be present in any factory or industrial area that uses plastic as a material, whether it be recycling or production) can cause health effects such as skin lesions, with pollutants such as dioxins playing a major role in this. Other symptoms include a change in liver function and fat metabolism, leading to higher instances of weakness and fatigue, along with a weakened immune system and possible damage to the nervous system.

What can Semarang do to reduce its pollution levels?

The city of Semarang can take many different steps to see a reduction in its pollution levels, with initiatives such as reducing the number of cars on the road, changing regulations on the quality of fuel as well as placing restrictions on how much pollutants a factory or industrial area can release. These would all go a long way in helping to bring down the elevated numbers of PM2.5.

An introduction of car free zones or days has been proven to put a sizeable dent in nitrogen dioxide and sulfur dioxide emissions, as well as reducing the amount of ozone and carbon monoxide in the air. With tighter restrictions on vehicle fuels being put into place, such as the phasing out of leaded fuels in 2006, new steps could be made to reduce the amount of fossil fuels being used, with a restriction on diesel fuel being a great start.

Factories can also be kept in check with their pollution emission levels by imposing fines on any that exceed a certain level of pollutive output, by monitoring the air in these industrial areas and fining factories that break the limits of what is considered a safe level of pollution. A collection of these steps would see drastic reductions in levels of both PM2.5 and PM10 and other hazardous materials in the air.

What other pollutants can be found in the air in Semarang?

Besides the huge amount of pollutants previously mentioned, there would be other ones finding their way into the atmosphere, and although they are less prominent that the main chemicals such as nitrogen dioxide, they still have a number of negative effects on the health of Semarang's citizens.

They would include black carbon and volatile organic compounds (VOC’s), both of which come from the combustion of fossil fuels and organic material. Others include benzene, formaldehyde, mercury and lead, as well as other plastic fumed based chemicals such as polynuclear aromatic hydrocarbons. Silica dust from construction sites can also be extremely harmful if not properly maintained, and as such all three of these offending sources, vehicles, factories and construction sites (as well as open burning sources) should all have close tabs on them if cities such as Semarang are to be successful in the ongoing war against pollution.