Air quality in Hita

What is the current level of air pollution in Hita?

Hita is a city located in Ōita Prefecture, Japan. It is an agricultural and industrial centre that primarily produces lumber, furniture and pottery. According to a census conducted in 2019, Hita had an estimated population of approximately 65,000 residents.

At the beginning of 2022, Hita was experiencing a period of “Moderate” air quality with a US AQI reading of 57. This United States Air Quality Index number is an internationally used set of metrics supported by the World Health Organisation (WHO) and is used to compare the air quality in different cities throughout the world using comparable standards. It is calculated by using the levels of the six most commonly found pollutants such as nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide and both sizes of particulate matter, which are PM2.5 and PM10. If all six figures are not always available in which case, a level is calculated by using what data there is. In Hita, four of the major pollutants were measured which were; PM2.5 - 15 µg/m³, PM10 - 10 µg/m³, nitrogen dioxide (NO₂) - 5.6 µg/m³ and sulphur dioxide (SO₂) - 0 µg/m³.

This level of PM2.5 is one and a half times above the recommended safe level of 10 µg/m³ as suggested by the World Health Organisation (WHO) as being an acceptable level. Although no amount of air pollution is considered to be safe.

When air pollution is classified as being “Moderate” the given advice would be to remain indoors as much as possible, closing doors and windows to prevent the ingress of more polluted air. Those who are more sensitive to poor quality air should avoid venturing outside until it improves. If this is unavoidable, then a good quality face mask should be worn at all times. All types of outdoor exercise should be avoided until the air quality improves. There is a downloadable app from AirVisual.com which is suitable for all operating systems and gives the latest information regarding air quality in real-time.

Does the level of air pollution vary much throughout the year in Hita?

Air quality can be affected by many things, therefore it can and does change rapidly depending on the local conditions. Looking back at the 2020 figures published by IQAir.com, it can be seen that for the month of July, Hita achieved the target figure of 10 µg/m³ or less as recommended by the WHO. The actual figure was 8.7 µg/m³. During the month of September, the air quality was classified as being “Good” with a reading of 11.8 µg/m³. For the remaining ten months of the year the air quality was classed as being “Moderate” with figures between 12.1 and 35.4 µg/m³. The dirtiest month was January with a reading of 19.9 µg/m³.

Records for air quality were first held in 2019 when a figure of 15.0 µg/m³ was noted. The following year saw a slight decline with a figure of 15.8 µg/m³. This lower figure was almost expected because it would have been affected by the COVID-19 pandemic as many vehicles were no longer in daily use because the offices were closed and the staff encouraged to work from home, in an attempt to halt the spread of the virus. Many factories and non-essential production units were also required to close which removed their emissions from the atmosphere, albeit on a temporary basis. Worldwide, cities reported a much better quality of air due to the general lack of traffic pollution in city centres due to the pandemic.

What is the main source of air pollution in Hita?

Although it has improved dramatically compared to the period of high economic growth, air pollutants such as sulphur oxides and nitrogen oxides are still emitted from factories and thermal power plants.

Since these air pollutants are regulated by the Air Pollution Control Law, each company has a dust collector that separates and removes particulate matter in gas, and smoke exhaust that removes sulphur oxides and elemental oxides in exhaust gas. We are working to reduce the amount by using technologies such as desulphurization and flue gas desulphurisation.

Air pollution in Japan is also caused by the movement by traffic, the increase in the number of cars owned, and the concentration of vehicles in big cities.

The government is tightening automobile emission regulations, but the current situation is that the achievement of environmental standards is unsatisfactory.

Air pollution caused by fuel consumption of thermal power plants, factories, automobiles, etc. in the Asian region where industrial development is advancing is also affecting Japan.

Combustion of fossil fuels releases air pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) into the atmosphere, producing harmful photochemical oxidants. In Japan, these pollutants are decreasing year by year due to source regulations, but it is thought that cross-border air pollution is the main reason why domestic ozone does not decrease at all.

What can be done to improve air quality in Hita?

All efforts are being made based on the "Automobile NOx / PM Law", a special measures law for reducing pollutants emitted from automobiles, but the spread of electric vehicles is particularly attracting attention as a measure against NOx.

Since electric vehicles use the electricity stored in the battery to run on motors, they do not emit any exhaust gas and are characterized by less pollutant content and less carbon dioxide emissions than ordinary vehicles.

Furthermore, if charging with renewable energy such as solar cells becomes common, it will not be necessary to consider emissions from power plants, and NOx and carbon dioxide emissions from automobiles can be reduced to zero.

Refrain from using a car and travel on foot or by bicycle. Try to avoid wasting electricity at home. By practicing energy saving, such as, it is possible to reduce exhaust gas and reduce air pollutant emissions during power generation.

What are the detrimental effects of breathing in polluted air?

Since PM2.5 has a very small particle size, it easily penetrates deep into the lungs and is thought to increase the risk of respiratory and circulatory diseases such as asthma and bronchitis. In particular, people with respiratory and circulatory diseases, the elderly and children are considered to be susceptible, so caution is required.

In patients with asthma or chronic obstructive pulmonary disease, highly polluted air can induce seizures (exacerbations). Lung diseases associated with air pollution increase the risk of heart and blood vessel disease and also increase the risk of lung cancer. Also, people living in areas with heavy traffic are at particular risk.