瑞士的空气质量

Is Switzerland a country with good air quality?

Switzerland, or the Swiss confederation as it is otherwise known, is a country located in the central region of Europe, with intersections in both western and south Europe. It is a landlocked country, with many geographical features such as mountain ranges and plateaus, features which can occasionally lend themselves to the accumulation of pollution in a city or country, due to a lack of wind on the ground level leading to clouds of smoke or fine particulate matters building up without prevailing winds to aid in dispersing them.

It shares borders with many other big European countries such as Italy, France, Germany and Austria, and is considered itself as a leading developed nation, being home to many international organizations as well as the birthplace of the Red Cross. Nowadays it is home to many multinational corporations, and in cities such as Zurich there are over 150 thousand companies alone, making it one of the foremost important economic zones in the world.

Subsequently, with such a large and powerful economy, with exports and trade also being a prominent part of it, there would be an associated elevation in pollution levels, with a steadily growing population coupled with an influx of workers leading to higher use of vehicles, and other anthropogenic activities pushing the scope of pollution readings.

Looking at the data taken over the course of 2019, Switzerland came in with a yearly PM2.5 reading of 10.89 μg/m³, putting it into the ‘good’ ratings category, which requires a PM2.5 reading of anywhere between 10 to 12 μg/m³, indicating that it was only 0.89 units away from being moved into the World Health Organizations (WHO's) target goal of 10 μg/m³ or less, for the best quality of air.

Whilst this is a respectable rating indeed, it stands to reason that many cities within Switzerland have less than optimal air pollution readings, with certain cities such as Rotkreuz and Liestal coming in with higher readings of 16.3 μg/m³ and 14.7 μg/m³ respectively. These were however balanced out in its yearly average by the large amount of cities with extremely good air quality, thus creating a good equilibrium but still with space for improvement.

PM2.5 refers to particulate matter that is 2.5 micrometers or less in diameter, making it roughly 3% the size of a human hair, and as such it is particularly dangerous when respired, going down to sizes as small as 0.001 microns across. Due to its extremely small size and health risk potential, it is used as a major component when calculating the overall levels of air quality (alongside other pollutants such as PM10, nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) being used to gauge the overall AQI, or air quality index).

Switzerland’s PM2.5 reading of 10.89 μg/m³ placed it in 76^th place out of all countries ranked worldwide, coming in just behind other countries such as the Netherlands, Germany and Japan. So overall as mentioned, it has a good quality of air in many of its cities, but with further improvements it will see even more optimal standards of air quality in the future, thus improving its ranking.

What are some of the causes of air pollution in Switzerland?

It is acknowledged that the overall level of air quality has improved in Switzerland since the eighties, with more stringent measures and reductions in large scale polluting offenders having been implemented significantly. However, there are still many causes of air pollution that come together to cause the elevated readings sometimes seen in many cities across the country, with related meteorological factors also playing a part in it (with seasons such as winter leading to an increase in energy consumption, as well as wood burning due to the cold weather, and as a result power plants ramping up their energy expenditure, although it must be mentioned that Switzerland is one of the leading pioneers in reducing pollution from sources such as these, turning their attention to sustainable energy, up to and including the contentious use of nuclear energy at a certain time).

Due to these weather related factors, there are certain times of the year that see significant elevations in their pollution levels, observable in the PM2.5 readings across nearly every city registered in the country.

Moving on, one of the more pertinent sources of pollution is from vehicle emissions, a source that finds itself being a constant issue worldwide, being fairly consistent as a leading cause of air contamination in many countries and cities alike. In 2020, due to the mass lockdowns imposed by the covid-19 outbreak, many cities saw massive drops in their pollution levels, with even certain geographical features such as distant mountains becoming visible for the first time in over twenty years, a phenomenon that was observed in cities throughout India.

In Switzerland, it has been measured that huge amounts of fine particulate matter such as microscopic particles of rubber have been accumulating over the years, borne from the use of vehicle tires, particularly in heavy duty ones such as trucks and lorries, in buildups weighing up to an estimated measurement of around 200 thousand tons of dispersed micro particles of rubber, in the last twenty years alone.

Besides causing the buildup of PM10 and other fine particulate matter, cars are responsible for putting out large amounts of dangerous chemical compounds such as nitrogen dioxide and sulfur dioxide, with nitrogen dioxide being the most prominent in its release in vehicles, often found in large quantities over areas that see high volumes of traffic. The measurement of nitrogen dioxide in certain areas is a telling sign of how much pollution is being caused by vehicles alone, with large quantities of nitrogen dioxide of correlating directly with high amounts of car and other vehicle usage.

As such, Swiss citizens who are exposed to such pollution levels on a daily basis (such as those that live near busy roads or have to undertake daily commutes through high traffic zones) may be at greater risk, particularly if they belong to a vulnerable demographic, such as the young, elderly, or those with compromised immune systems or preexisting medical conditions.

So, whilst it is a country that is leading the way in reducing its pollution levels through a large number of initiatives, it still stands that much of its pollution comes from vehicle usage, despite stringent vehicle emission regulations. As well as this, there is also air contamination from other sources such as factories, industrial areas and even construction sites. Switzerland has placed many emission caps on these areas, but even so they will continue to contribute to the year round ambient pollution readings, with even small scale use of burning wood or charcoal in rural or traditional homes for heating or cooking also contributing to pollution levels and particulate matter in the air.

When is air pollution in Switzerland at its worst?

Observing the data taken over the course of 2019 as a good indicator of Switzerland's overall pollution levels, it is visible that there is a distinct pattern over the different cities registered in Switzerland as to when the PM2.5 levels are higher and when they start to recede. Using the city of Lucerne as a good mid-range example (not overtly polluted but not one of the cleanest cities either), it can be seen that the air quality levels start to decline in November, towards the end of the year, when the winter months begin to take hold and temperatures start to plummet.

To give an example of the numbers observed, Lucerne had a PM2.5 reading of 8.9 μg/m³ in October, which rose suddenly to 13.2 μg/m³ in November, also coming in with the same reading of 13.2 μg/m³ in December. Pollution levels stayed elevated at the beginning of the year, demonstrating that the rising pollution numbers at years end carry over to the following year. The months of January, February and April all had PM2.5 readings of 14.8 μg/m³, 17.2 μg/m³ and 16.4 μg/m³ respectively, making February the most polluted month in 2019 for Lucerne, as well as highlighting that the months of November through to April of the following year are when pollution levels are at their highest.

To further demonstrate the high readings on record during these months, other cities that came in with high PM2.5 numbers during this time period were ones such as Dubendorf, with a reading of 19.1 μg/m³ in November. Ecublens, a city in the south western region of Switzerland, came in with a reading of 23 μg/m³ in February, another highly elevated reading during the aforementioned high pollution period. In finishing, the month of February also saw some equally high readings in the cities of Liestal and Rotkreuz, with readings of 26.3 μg/m³ and 31 μg/m³ respectively.

This made February in Rotkreuz come in with the highest PM2.5 number throughout the entire year, a significant reading that is only a few units away from moving up a notch into the ‘unhealthy for sensitive groups’ bracket, a rating that requires a PM2.5 reading of anywhere between 35.5 to 55.4 μg/m³ to be classified as such, and as the name implies, is of great detriment to any vulnerable portions of the population.

To reevaluate, the months of November through to April of the following year are subject to the worst pollution levels, and for those looking to reduce their exposure, the use of air quality maps available on the IQAir website, as well as the AirVisual app may be of considerable help for those who want to stay up to date on hourly pollution readings, and utilize preventative measures, such as the wearing of fine particle filtering masks or the avoidance of outdoor activities or exercise when readings are particularly high.

Has the air quality in Switzerland improved over the last few years?

Looking at the data taken over the last few years, it can be seen that an improvement was indeed made between 2018 and 2019. In 2018, Switzerland came in with a PM2.5 reading of 11.63 μg/m³, and whilst this is not a number that is of any great excess when compared to the reading of 10.89 μg/m³ taken in 2019, it still nevertheless represents a step in the right direction, and if Switzerland's history of consistently restoring its air quality since the 1980’s is anything to go by, the country may see gradual increases in its air quality rating in the following years.

This is a feat which is certainly possible due to the continued implementation of pollution reducing measures, as well as personal responsibility amongst individual citizens taking part. The readings following 2020’s yearly average will be the true indicator as to whether Switzerland's air quality has made continued progress, or is just showing fluctuations between similar low pollution readings, as is sometimes seen in countries throughout the world.

When is the air quality at its best in Switzerland?

Carrying on from the previous question regarding when the pollution levels are at their worst in Switzerland, in contrast, the recorded numbers also show the periods of time across all cities as to when the air quality is at its best, free from the smoke, haze, smog and any other air contaminants that may be permeating the atmosphere during the more polluted months.

Once again using the City of Lucerne as an example, as well as Bern, as mentioned before the air quality starts to deteriorate rapidly around November, when the winter months start to take hold, continuing on until April of the next year. Apart from a pollution reading abnormality present in the month of March (where in nearly all cities recorded, it shows a rapid drop from the month prior, before jumping up again in April, making it slightly anomalous in nature), it is during May when the pollution levels start to take a turn for the better.

For contrast, in both Lucerne and Bern, they showed PM2.5 readings of 16.4 μg/m³ and 13.8 μg/m³ in the month of April respectively. In the following month of May, they both dropped to 7.6 μg/m³ and 8.5 μg/m³, unanimously displaying that this month is when the pollution levels start to abate (with many similar occurrences taking place across the whole country).

So, from there on out, the pollution levels stay within the WHO's target rating of 10 μg/m³ or less. This continues until the eventual air quality decline in November, with 13 out of 20 cities on record in Switzerland coming in with consistent WHO target readings between the months of May to October. The cleanest city countrywide in 2019 was Kussnacht, which came in with a yearly average of 6.3 μg/m³, and had the cleanest month on record out of every city, with a very respectable reading of 3.4 μg/m³ taken in October.