Qualité de l’air à London

Is London a city with good air quality?

London is a city located in Ontario, in the southwestern region of the province. It finds itself situated along the Quebec City-Windsor corridor, a name given to the heavily industrialized and densely populated region of Canada that lies between the two aforementioned areas. The city is well known for its higher education centers as well as healthcare, also being a hub for many festivals focused on music and the arts. These are factors that draw in many tourists, both local and internationally, and with an international airport and many well connected routes between other major cities in Canada, London would subsequently see elevations in its pollution levels. Of note is that even cities that see a large amount of human or industrial activity in Canada still manage to maintain a very good quality of air, and as such Canada remains as one of the cleanest countries ranked in the world.

In 2019, London came in with a PM2.5 reading of 6.4 μg/m³, a very respectable reading of air quality despite the activity taking place within the city (as well as having a sizeable population of 383 thousand inhabitants). This reading of 6.4 μg/m³ placed it within the World Health Organizations (WHO's) target goal for the best air quality at 10 μg/m³ or less, with the closer to 0 being of course the most optimal. As well as being placed into the best air quality bracket, it also came in at 4013^th place out of all cities ranked worldwide, as well as 90^th place out of all cities ranked in Canada. This shows that on the world circuit it has a very good quality of air, amongst some of the best in the world, but within Canada it could certainly stand to improve its air quality levels further and achieve even more respectable qualities of air.

What are some of the main causes of pollution in London?

London would be subject to the same causes of pollution that many cities across Canada see. These include ones such as the use or over reliance on vehicles, something which is pervasive throughout nearly every city around the world, being one of the leading causes of lower air quality as well as many other unwanted pollutive events such as smog buildup or haze clouds. Many cars on the road would drive up the chemical pollutant count as well as the amount of fine particulate matter (PM2.5 or PM10) in the air, and heavier vehicles such as trucks, lorries, buses and even snow ploughs would contribute more so, due to them often running on diesel fuels, as well as their great size and weight assisting them in putting out far more pollution.

Other causes of pollution in London include emissions from power plants, factories and other similar industrial areas, many of which still utilize fossil fuels such as coal for their power, which can be driven up during the colder months due to increased demand for energy to heat both homes and businesses. Other minor factors would be rubber particle buildup caused by the wearing down of tires on roads, as well as the burning of wood and other materials often done during colder periods.

When is the air quality at its worst in London?

Observing the data taken over the course of 2019, London displayed its higher levels of PM2.5 during the associated winter months, as is a common sight worldwide. Due to the large drops in temperature, people will typically resort to using larger amounts of energy to heat their homes and businesses, as previously mentioned. Some people will still practice older heating methods such as using charcoal or wood in their fireplaces or stoves to provide heat, which in of itself is not too impactful, but when done by thousands of people can have a disastrous effect on the environment.

November onwards was when the pollution levels started to take a turn for the worst, with October coming in with a still clean reading of 5 μg/m³, which was then followed by a jump up to 7.9 μg/m³ in October, and then further up to 8.6 μg/m³ in December.

The early months of the year also showed mild elevations, with readings of 6.8 μg/m³ in January and 7.2 μg/m³ taken in March. In closing, the months of November through to March of the following year were when London saw its highest levels of pollution, with December being the most polluted month with its reading of 8.6 μg/m³.

When is air quality at its cleanest in London?

In following from the previous question, the months that came in with the best readings of PM2.5 over the course of 2019 were taken between August and October, which all came in with readings of 5 μg/m³, 5.8 μg/m³ and 5 μg/m³ respectively. This displayed that both August and October were the cleanest months of the year, with matching readings of 5 μg/m³ both on record, indicating that the air would be the freest from smoke, haze and other contaminating materials during these time periods.

What are some of the main types of pollutants found in the air in London?

Due to a large majority of its pollution coming from sources such as vehicles, as well as other combustion sources such as power plants, factories and the burning of firewood and other materials, the pollutants would subsequently be closely related to these elements. Chemical compounds such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) would be found in areas that see a high level of traffic, both of which can contribute to incidences of acid rain, as well as having the ability to cause irritation and inflammation to the lining of the lungs and respiratory tract, as well as triggering off preexisting health conditions such as asthma.

Other pollutants would be ones such as carbon monoxide (CO) and ozone (O₃), otherwise known as smog and typically forming as a secondary pollutant during the hotter months of the year. When the various oxides of nitrogen (NOx) are released from sources such as cars, when they are subject to concentrated amounts of solar radiation from sunlight, they can convert into ozone. Whilst this is a vital chemical compound in the upper atmosphere, when found on ground level it can cause severe adverse health effects when over exposure occurs.