Qualité de l’air à Kobe

What is the air quality like in Kobe?

Kobe is a city in Japan, being the capital city of the Hyogo prefecture. It is the 7^th largest city in Japan, with some 1.5 million or more inhabitants living within the city’s limits, and over 2.4 million in the metropolitan areas. Kobe was one of the first cities to open its doors to trade with the west after Japan's long period of seclusion, becoming well known as a metropolitan port city, with much of its industry centered around the shipping of goods and international trade, as well as local industries revolving around the production of metals, food products (such as the famous Kobe beef) and electronics.

With all of these activities and large movements of people, there are subsequent rises in pollution levels, as is inevitable in all cities round the world. In 2019 Kobe came in with a PM2.5 reading of 11.4 μg/m³.

This reading placed Kobe into the ‘good’ ratings bracket of air quality, which requires a PM2.5 reading of anywhere between 10 to 12 μg/m³ to be classed as such, a fine margin of entry and only 1.4 units away from being moved down into the World Health Organizations (WHO's) target goal of 10 μg/m³ or less for the best possible quality of air, with the closer to 0 being the most optimal for clean air.

As well as being in the good ratings category for its yearly average, Kobe's reading of 11.4 μg/m³ put it in 256^th place out of all cities ranked in Japan over 2019, as well as 2031^st place out of all cities ranked in the world. This is a respectable reading and placing, showing that Kobe has a good quality of air, however at the same time there are a few pollutive issues manifest in the city, with certain months having higher readings that could be damaging to the health of certain individuals.

What are the main causes of pollution in Kobe?

With a high volume of people moving around the city, as well as in and out for cross country commutes, subsequently there would be a large amount of pollution coming from the source of vehicles. Although Kobe and many cities throughout Japan have a significant amount of public transport infrastructure and money invested into them, cars and motorbikes and any form of private transport still remains prevalent, causing pollution levels to be far higher year round than they should be.

Other vehicles that contribute would be ones such as ships, prominent in port cities and often containing higher levels of chemicals such as sulfur in their fuel which can cause more sulfur oxides to be released as a result. Heavy duty vehicles are also an issue, with trucks, lorries and buses still in use, sometimes running on diesel fuels that can put out large amounts of pollution associated with the combustion of fossil fuels.

Other prominent sources of pollution in Kobe would be emissions from factories, with vast amounts of production plants and industrial areas being available across the city limits, often running on coal as well as utilizing diesel for the powering of their heavy machinery, not to count the industrial effluence that is released as a byproduct from whatever item is being produced (for example plastic product factories inevitably release some form of plastic fumes into the atmosphere).

When is pollution in Kobe at its worst?

Observing the data taken over the course of 2019, Kobe showed some very significant patterns in its pollution levels, with distinct changes in pollution between the different months of the year. It appears that the beginning portion of the year through to August are when the pollution levels were slightly higher, with the very beginning of the year being the absolute worst.

For some context and numbers, the months of February, March and May all came in with the worst readings of PM2.5, all sitting in the ‘moderate’ ratings bracket, which requires a reading of anywhere between 12.1 to 35.4 μg/m³ to be classed as such. The surrounding months were all in the good bracket, and therefore not of the greatest concern.

The aforementioned worst months of the year all came in with PM2.5 readings of 17.3 μg/m³ in February, 13.5 μg/m³ in March and 14 μg/m³ in May. This displays that the most polluted time of the year was within the first 5 months, with February being the most polluted out of the entire year.

When is Kobe’s air quality at its cleanest?

In contrast to the previous question and answer, the months that came in with the cleanest readings of PM2.5 in 2019 came at the end of the year, whilst the most polluted came at the beginning. Pollution levels remained somewhat stable up until August, which came in with a reading of 11.4 μg/m³.

From here on out, for the next three months the pollution levels dropped significantly, with September through to November all having the cleanest readings of air quality. In terms of numbers, September came in at 9 μg/m³, October at 8.2 μg/m³ and November at 9 μg/m³ once again.

After this clean spell the PM2.5 readings went back up into the ‘good ratings category of 10 μg/m³ or above. With the numbers on record, October was the cleanest month of the year for Kobe, falling within the WHO's target goal with both September and November doing the same.

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

With a large amount of its pollution emanating from vehicular sources, as well as industrial fumes, Kobe’s polluted air would contain a certain amount of harmful chemical compounds and fine particulate matters.

Some of these would include, as seen mostly released from vehicles, oxides of nitrogen and sulfur, most prominently nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). Nitrogen dioxide would be the most widespread pollutant, often correlating directly with high levels of traffic, with large concentrations of it on ground level and in the atmosphere over areas that see many cars and other vehicles.

Other pollutants would include carbon monoxide (CO), volatile organic compounds (VOC's) such as benzene, toluene and formaldehyde, as well as black carbon and polynuclear aromatic hydrocarbons, all of which are highly detrimental to human health and extremely easy to respire, in particular the VOC's due to them being gaseous at much lower temperatures due to their volatile compositions.