Qualité de l’air à Leganes

What is the current level of air pollution in Leganés?

Leganés is a city in the Community of Madrid, Spain. Considered part of the Madrid metropolitan area, it is located about 11 kilometres southwest of the city centre. According to a survey conducted in2018, Leganés had an estimated population of approximately 188,500 inhabitants. This ranked it as the fifth most populous municipality.

Towards the end of 2021, Leganés was going through a period of “Moderate” air quality with a US AQI reading of 61. This reading is often used as a reference point when comparing air quality in other cities around the world. Data is collected with regards to the six most prolific air pollutants commonly found and this figure is calculated from there. If information is not available for all six, then a figure can be deduced using the information that is available. For Leganés, there were four pollutants measured which were; PM2.5 - 17 µg/m³, PM10 - 25 µg/m³, ozone (O₃) - 25 µg/m³ and nitrogen dioxide (NO₂) - 47 µg/m³.

The level of PM2.5 can be seen to be just over one and a half times higher than the suggested level of 10 µg/m³. This level has been determined by the World Health Organisation (WHO) as being an acceptable level of air pollution, although no level is to be considered as being safe.

When the air quality is classified as being “Moderate”, the given advice would be to remain indoors as much as possible and close all doors and windows to prevent more polluted air from getting inside. Those who are more sensitive to poor air quality should avoid going outside until the air quality improves. If this is unavoidable, then a good quality mask should be worn at all times. All groups are dissuaded from partaking in vigorous outdoor exercise. There is a downloadable app from AirVisual which is available for most operating systems which informs the user of real-time air quality which can be useful information to help decide what to do.

Does the air quality vary throughout the year in Leganés?

Looking back at the figures published by IQAir.com for 2020, the months of the year were very disjointed. January and February, July and November all returned figures from the “Moderate” category between 12.1 and 35.4 µg/m³. The months of June, August, September and December all offered “Good” readings between 10 and 12 µg/m³. The remaining months of March, April and May, together with October all achieved less than the target figure of 10 µg/m³ as recommended by the WHO.

Records for air quality were first kept in 2019 when the air quality was recorded as being “Good” with a figure of 12 µg/m³. A slight deterioration was seen in 2020 when that figure was 13 µg/m³ which pushed it into the “Moderate” bracket. However, the figures for 2020 were not always what they seem because of the COVID-19 pandemic. Many cities throughout the world reported much cleaner air in their centres because of the lack of vehicles using the roads on a daily basis. There were also some factories and small production units which were temporarily closed so their emissions were halted.

Where does the air pollution come from in Leganés?

Road traffic is the cause that leads the ranking of pollutant sources in the city of Leganés. The residential, commercial and institutional sector, which refers mainly to non-industrial air conditioning systems, which represent 18.1 per cent of nitrogen oxide emissions. Finally, the industrial sector comes next without reaching 7 per cent of emissions.

Recently, the measurement stations in Leganés and other nearby points have collected high values of PM10 and PM2.5 particles and nitrogen dioxide, but not so high as to activate the municipal protocol. The technical services of the Sustainability Delegation report that the cold temperature situation with thermal inversion is responsible for the PM10 and PM2.5 particles having reached high values. Meteorological stability does not allow the dispersion of pollutants, which is why their concentrations are increasing as a result of road traffic, amongst other causes.

Can anything be done to improve air quality in Leganés?

With the aim of improving pollution levels and therefore the quality of the air breathed, the City Council is developing Plan A, which includes 21 measures related to traffic, but also others related to other sectors, such as the elimination of coal.

In 2018, 18 diesel boilers were eliminated from municipal buildings and facilities, which meant eliminating 67 per cent of current diesel consumption. In 2019, diesel boilers were mainly history in the city environs.

Methane is a very powerful climate pollutant, as well as an atmospheric pollutant associated with agricultural activities, closely intertwined with livestock production and meat consumption. Particulate matter is another pollutant that affects both climate change and air quality. Depending on its composition, it can have a cooling or warming effect on the local and global climate. For example, black carbon, which is one of the components of fine particulate matter and the result of incomplete combustion of fuels, absorbs solar and infrared radiation in the atmosphere and therefore causes a warming effect.

What are the effects of air pollution on health?

Outdoor ambient air pollution is a broader term used to describe air pollution in outdoor environments. Poor outdoor ambient air quality occurs when pollutants reach concentrations high enough to negatively affect human health and / or the environment. Outdoor urban air pollution is a more specific term that refers to outdoor ambient air pollution in urban areas, usually in or around cities.

Exposure to high levels of air pollution can cause a variety of adverse health outcomes. Air pollution can increase the risk of respiratory infections, heart disease, stroke, and lung cancer. Both short-term and long-term exposure to air pollutants has been associated with adverse health impacts. The most severe impacts affect people who are already sick. Children, the elderly and the poor are most susceptible. The most harmful pollutants for health, closely associated with excessive premature mortality, are fine PM2.5 particles that penetrate deep into the lung ducts.

Particulate matter (PM) is the term for particles that are suspended in the air, such as dust, soot, smoke and aerosol. Large amounts of particulate matter are typically emitted from sources such as diesel vehicles, burning waste and crops and coal-fired power plants.

Particles less than 10 microns in diameter (PM10) present a health problem because they can be inhaled and accumulate in the respiratory system. Particles less than 2.5 microns in diameter (PM2.5) are called "fine" particles and pose greater health risks. Due to its small size, fine particles can lodge deep in the lungs.