Qualité de l’air à Weinan

What is the state of the air pollution in Weinan?

Weinan is a prefecture-level city in the east-central Shaanxi province of China. It is situated along the lower section of the Wei River where it joins the Yellow River. The city is almost divided into two distinct areas, the urban areas lie mainly south of the river whilst the metropolitan area is on the north bank. It is around 60 kilometres east of the provincial capital of Xi’an. According to the 2010 census, Weinan had a population of 5.5 million of which 660,000 lived in the southern urban district. After the passing of eleven years, it is expected that this figure is considerably higher now.

At the start of the second quarter of 2021, Weinan was experiencing a period of “Unhealthy” air with a US AQI reading of 152. This classification level is in accordance with recommendations by the World Health Organisation (WHO). The classification is based on the measurements of six most commonly found pollutants and then used as a benchmark when comparing other cities and/or areas. The recorded levels of these six main pollutants were as follows: PM2.5 - 57.5 µg/m³, PM10 - 88 µg/m³, ozone (O₃) - 75 µg/m³, nitrogen dioxide (NO₂) - 21.5 µg/m³, sulphur dioxide (SO₂) - 7 µg/m³ and carbon monoxide (CO) - 846 µg/m³. For relatively high levels such as these, the advice would be to stay indoors and close doors and windows to prevent the ingress of more dirty air. Even healthy people are advised against exercising outdoors until the air quality improves. If venturing outside is inevitable, then a good quality mask should be worn at all times. When indoors, consider using an air purifier if one is available.

Does the level of air pollution vary in Weinan throughout the year?

Looking back at the figures for 2020 which have just been released by the Swiss company IQAir.com. The levels of pollution can be seen to be equally split according to the seasons. The best quality air was found in the warmer summer months of May through to the end of August. It was classified as being of “Moderate “quality with figures between 12.1 and 35.4 µg/m³. During the spring and autumn seasons, the quality slipped into the next category which is “Unhealthy for sensitive groups”. During March and April, the readings were 44.2 and 37.6 µg/m³ respectively and 37.1 and 48.8 µg/m³ for the autumn months of September and October. The last third of the year is winter from the start of November until the end of February. This time of the year is the coldest when homes and businesses need to be heated which pushes the air quality down to “Unhealthy” levels with figures between 55.5 and 150.4 µg/m³.

Historically, records were first kept in 2017 when the annual average reading was 68.8 µg/m³. And a slight improvement can be seen year on year since then. The following year of 2018 returned a figure of 58.2 µg/m³, followed by 55.6 µg/m³ in 2019. The average figure for 2020 was 52.5 µg/m³ but it might be artificially low because of the restrictions put in place due to the COVID-19 pandemic. Personal travel by private vehicle was prohibited and certain industrial practice had to cease for several months at a time. This resulted in the reduction of the emission of pollutants and thus the improvement of the air quality in many cities in China.

Where does all this dirty air come from in Weinan?

The winter can take the harshest toll on human health in Weinan when coal-burning is at its height. Burning coal releases nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and particulate matter (PM10 or PM2.5)—all of which are dangerous in high doses. Sulphur dioxide not only damages crops and other flora, but can impair breathing and aggravate existing heart disease.

Results showed that the main six sources of PM2.5 were coal-fired (38.48 per cent), secondary (19.19 per cent), biomass burning (15.04 per cent), industry (9.28 per cent), traffic (5.02 per cent) and dust (5.00 per cent).

The major cause of the atmospheric heavy haze is unfavourable meteorological conditions such as high humidity and low wind speed, as well as coal-fired pollution and secondary pollution caused by heating and industrial production.

What can be done to reduce the air pollution in Weinan?

With the continuous development of reform and opening up, Weinan City has achieved remarkable results in economic development, but the atmospheric environment has declined because of it. Sulphur dioxide is one of the main pollutants with a wide distribution and greater impact in the atmosphere, and it is often used as the main indicator to measure the degree of atmospheric pollution. Sulphur dioxide mainly comes from factories and enterprises that use coal or petroleum as fuel, such as thermal power plants, steel plants, non-ferrous metal smelters, and petrochemical plants.

Weinan City has intensified its efforts to create sanitation, become a provincial model city, and establish more urban greening. In addition, the adjustment of the urban energy structure in Weinan, the normal operation of desulphurisation facilities in coal-fired power plants, the continuous expansion of urban coal-to-gas conversion areas, the transformation of urban coal-fired boilers, and the use of clean fuels have all significantly reduced the concentration of sulphur dioxide in the urban area. The quality of the air environment in Weinan City is starting to improve.

How does polluted air affect human health?

Breathing polluted air not only causes irritation in the throat but also can cause serious diseases because greenhouse gases and airborne particles can damage the human lungs and cause diseases such as asthma. Children and adults are not immune. In addition, air pollution can cause damage to various organs of the human body.

Diseases caused by pollution are different for every person in every community. Children often have more health problems than adults because they are smaller and still developing. Some problems affect women more than men. Inside and outside the factory, health problems caused by chemicals depend on the type of chemicals, the way they are in contact with them, and the frequency and time of contact.

Outdoor air pollution is one of the most serious killers in the world, and it will shorten the lifespan of people. It is estimated that air pollution causes about 3 million people to die prematurely each year.