Qualité de l’air à St. John's

Does St. Johns have clean air?

St. Johns is a city located within the Canadian province of Newfoundland and Labrador, being both the capital city as well as the largest in the province, home to over 108 thousand people as of a census taken in 2016. It is a city that sees some very respectable levels of air quality, with Canada already being a country that ranks amongst the highest in the world in terms of air cleanliness. Despite this however, it is not without its pollutive issues, and whilst it maintains a very good level of PM2.5 on record, there are still some factors that contribute to worsened air quality, particularly in certain areas, or pollutive hotspots as they are known.

In 2019, St. Johns was recorded as having a PM2.5 reading of 5.1 μg/m³ as its yearly average, a very good reading that would place the city into the World Health Organizations (WHO's) target bracket for the best quality of air, at 10 μg/m³ or less, with the closer to 0 of course being the most optimal and ultimate end goal. Whilst there were certain months when the PM2.5 count climbed slightly higher due to several factors, St. Johns still displayed a very good level of air quality, with its reading of 5.1 μg/m³ placing it in 4422^nd place out of all cities ranked worldwide, as well as 134^th place out of all cities ranked in Canada.

Does St. Johns have any pollution problems?

As mentioned previously, whilst St. Johns maintains a very good quality of air year round, never breaking out of the WHO's target goal of 10 μg/m³ or less, it still stands to reason that there are several factors that are causing the PM2.5 count to be slightly higher than it possibly could be, with large amounts of anthropogenic activity, coupled with industrial factors coming together to raise the pollution level. PM2.5 refers to particulate matter that is 2.5 micrometers of less in diameter (sometimes going down to sizes as small as 0.001 microns or beyond), and due to its incredibly small size, is of extreme detriment to human health when inhaled, and thus is used as one of the major components in calculating the overall air quality of any given location.

Pollution sources found in St. Johns would include ones such as cars, trucks and lorries, all of which would be found in high numbers on the road at any given time. Vehicular exhaust fumes are one of the worlds leading causes of pollution issues, and as the population number rises, so too does vehicle ownership. On top of this, heavy duty vehicles such as the aforementioned trucks and lorries tend to put out much larger amounts of fumes and dangerous particulate matter, more so than a singular vehicle of a smaller size would.

Additionally, they often run on diesel fuel, which can have a more polluting effect when combusted. Tons of microscopic rubber particles are also left behind when tires are worn down, which can affect both human health when respired, as well as wildlife. Other pollution sources would also include the burning of firewood or charcoal during the colder months, as well as coal burnt by factories or power plants, to supply energy to the general population.

When is the air at its most polluted in St. Johns?

Observing the data taken over the course of 2019 as an indicator of when the pollution levels were subject to a heightened change, it can be seen that there was indeed a period of time when the PM2.5 readings were elevated, albeit for quite a brief period of time. These months also coincided with the winter period, as is quite often the case in many cities across the world, due to the increased energy demand for heating in homes and businesses, as well as larger amounts of wood and other organic material being burnt.

November came in with a very clean reading of 4.3 μg/m³, which was then followed by an elevation up to 5.8 μg/m³ in December. These heightened readings then continued on into the early months of the year (with winter running generally from December to March). February presented with a reading of 5.2 μg/m³, then 6.3 μg/m³ in March, followed by 5.8 μg/m³ in April before the PM2.5 readings started to drop again. This shows that the period of time between December through to April was when the air was slightly more polluted in St. Johns, with March being the most polluted month of 2019 with its reading of 6.3 μg/m³.

When is the air quality at its cleanest in St. Johns?

In following from the previous question, after the period of heightened pollution levels came to a close, a period where the PM2.5 count was even lower and more appreciable took place. After April presented with its reading of 5.8 μg/m³, a sudden drop then took place in the following month, with May coming in at 4.2 μg/m³. This period of cleaner air quality (save for an abnormally high reading in July) ran from the months of May through to November, with September being the cleanest month of the entire year with a very respectable reading of 3.1 μg/m³ having been recorded.

What are the main types of pollution found in St. Johns?

As mentioned, whilst the air quality in St. Johns is exceptionally clean, with only a few periods of time showing slightly higher readings, it still stands to reason that the polluting sources would leave a certain amount of pollutants in both the ground level air and atmosphere. A majority of these would be related to combustion sources, with factories, power plants and car engines (as well as even fireplaces) all contributing to these pollutants.

Some of the main ones would include chemical compounds such as nitrogen dioxide (NO²) and sulfur dioxide (SO₂), as well as carbon monoxide (CO), the various oxides of nitrogen (NOx), and ozone (O³), or as it is known in more common terminology when it accumulates enough, smog. Nitrogen dioxide would be the chief offender in its release from vehicles, which along with sulfur dioxide, can contribute to instances of acid rain, as well as causing inflammation and irritation to the lining of the lungs and respiratory tract of anyone who breathes it.

The aforementioned oxides of nitrogen can also contribute to the creation of ozone, with exposure to sunlight and solar radiation causing them to convert into ozone and thus clouds of smog if the amount is large enough. Whilst it is a vital part of the upper atmosphere, on the ground level it is an extremely harmful pollutant that can cause a myriad of unpleasant and dangerous health effects.