川崎市的空气质量

Does Kawasaki have good air quality?

Kawasaki is a city in Japan, located in the Kanagawa prefecture, being counted as one of the bigger cities in the great Tokyo area. It is a large and densely populated city, being the 8^th most populous out of the whole of Japan. Kawasaki has an estimated population of some 1.5 million or more inhabits, with over 700 thousand households present. These facts would certainly present the city with some pollution issues, as high population density coupled with development and infrastructure often leads to several sources of pollution being present.

In 2019, Kawasaki came in with PM2.5 readings of 11.3 μg/m³, placing it into the ‘good’ ratings bracket, which requires a PM2.5 reading of anywhere between 10 to 12 μg/m³ to be classed as such. This bracket requires a very fine margin of entry, and indicates a respectable quality of air, although with room for improvement. Any PM2.5 reading over the World Health Organizations (WHO) target goal of 0 to 10 μg/m³ can have adverse effects on the health of those who respire polluted air, with incidences of these adverse effects going up in correlation with higher readings.

Kawasaki’s yearly average of 11.3 μg/m³ was enough to put it into 2068^th place out of all cities ranked worldwide, as well as 267^th place out of all cities ranked in Japan. As touched on before, this is a good quality of air, as its rating would infer, however there are months when pollution levels rise significantly, and as such, there would be plenty of room for improvement for the quality of air in Kawasaki.

What are the main causes of pollution in Kawasaki?

Having been a major powerhouse in the movement of driving Japan's massive economic growth during the 60’s and 70’s, Kawasaki subsequently had large amounts of industrial areas, power plants and factories scattered around the city’s limits. Whilst their pollutive output is not as high as it may once have been, and with far tighter and more stringent regulations on what chemicals factories are allowed to pump out, it still stands to reason that with a large amount of its economy based on the production and exportation of goods, large amounts of pollution would also arise from this singular source.

Other causes of pollution would be further anthropogenic (human caused) ones, and with the aforementioned large and condensed population, there would be the inevitable high usage of personal vehicles, with fumes from cars and motorbikes helping to drive up the year round ambient pollution levels, as well as industrial heavy duty vehicles such as lorries, buses and trucks also contributing, carrying goods in and out of the city as well as ferrying people and other products around within the city itself.

These heavy duty vehicles often run on diesel fuels, and although Japan is several steps ahead of many countries in the region in regards to rules and regulations, the continued use of diesel fuel inevitably ends up being a factor that contributes to both noxious chemical compounds as well as dangerous particulate matter being in the air. These would be the two leading factors in air pollution in Kawasaki, vehicular and industrial emissions.

When is pollution at its worst in Kawasaki?

Observing the data taken over 2019 (with this year being the most optimal in recent times due to the covid-19 outbreak skewing pollution readings due to mass lockdowns), the months that came in with the highest PM2.5 readings were spread out through the beginning portion of the year, not having a particularly strong pattern to them, but nevertheless being relegated to the first three quarters of the year, with fluctuating PM2.5 levels going between ‘good’ rating readings up to ‘moderate’ readings, which requires a PM2.5 number of anywhere between 12.1 to 35.4 μg/m³ to be classed as such.

The months that came in with the highest levels of pollution were February, March, May and August, with readings of 16 μg/m³, 13.4 μg/m³, 12.4 μg/m³ and 12.8 μg/m³ respectively. This indicates that February was by far the most polluted month out of the year, with PM2.5 readings close to double that of the cleanest readings. Whilst these numbers are not excessive by any means, they could still present some health risks to vulnerable portions of the population, with demographics such as the young, elderly, the immunocompromised or those with preexisting health conditions being the most at risk, along with pregnant mothers also being highly vulnerable.

When is the air quality at its cleanest in Kawasaki?

In contrast to the previous question, the months that came in with the cleanest qualities of air occurred towards the end of the year, with only two months out of the entire year falling into the WHO's target goal of 10 μg/m³ or less, representing the best quality of air, with closer to 0 of course being the most optimal.

After another spike in pollution in August of 12.8 μg/m³, the level fell to 10.3 μg/m³ in September, before reaching the two cleanest months of October and November. They both had PM2.5 readings of 9 μg/m³ and 8.9 μg/m³ respectively, making October the cleanest month of the year, and as mentioned the PM2.5 readings were nearly half of what was recorded in the most polluted month of February. In the months of October and November, the air would be significantly freer from smog, haze, fumes and other contaminants that spoil the quality of air and cause adverse effects amongst those breathing it.

What type of pollutants would be found in the air in Kawasaki?

With much of its pollution coming from combustive sources such as factories, industrial areas as well as vehicle emissions, the subsequent pollution and particulate matter would follow accordingly. In areas that see high volumes of cars, particularly in the city center or along major motorways, chemical compounds such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) would be found in abundance, with nitrogen dioxide being the most prominent of the two in terms of its release from vehicles.

Other pollutants released from industrial areas would be all manner of metals, many of which are toxic and can enter into the air in fine particles, or into the food chain and even bodies of water. These would be iron particles, along with more dangerous metals such as mercury, cadmium, lead and chromium.

Lastly, pollutants such as black carbon and volatile organic compounds would be found, both finding their creation in the combustion of fossil fuels as well as organic matter, and thus would be found coming both from factories as well as vehicles that run on diesel. Some examples of VOC's would be highly dangerous chemicals such as benzene, toluene, xylene and formaldehyde.