Qualité de l’air à Sheffield

How bad is the air quality in Sheffield?

Sheffield is a city in the mid region of the United Kingdom, being a metropolitan borough of South Yorkshire. It has a long history of industry, playing a large role in the industrial revolution of the late 1700’s through to the mid 1800’s. Historically this means that Sheffield would have seen some varying and somewhat elevated levels of pollution due to the massive amounts of coals and other fossil fuels used during that era. This is something that is still seen today, with pollution levels being unusually high for a city in the United Kingdom, especially one that is known for being surrounded so heavily by trees and forest land, although the reasons and causes for pollution levels have of course changed with the passage of time.

To observe the readings of pollution levels taken over 2019, Sheffield came in with a yearly average of 12.7 µg/m³ in regards to its PM2.5 in the air. This PM2.5 refers to tiny particulate matter approximately 3% of the size of a human hair, or 2.5 micrometers or less in diameter.

Back to the yearly average, this reading of 12.7 µg/m³ is as mentioned, fairly elevated for the United Kingdom, putting in 5^th place out of all 130 cities ranked in the U.K in 2019. It would also be classified in the ‘moderately’ polluted bracket, which requires a PM2.5 reading of anywhere between 12.1 and 35.4 µg/m³ to be labelled as such. Of note is that only 14 cities in the U.K achieved this ranking in 2019, making the quality of air in Sheffield less than desirable to breathe, although there were a few months of respite from the higher levels of pollution, which will be discussed in short. It also ranked in 1597^th place out of the most polluted cities in the world, showing that whilst by England's standards it is not faring too well, there are many more polluted cities around the world coming in way ahead of it.

What are the main causes of pollution in Sheffield?

With higher numbers than the rest of the country, Sheffield would see a variety of pollutants and fine particle matters permeating the air. These would come from several sources, with two main offenders topping the list. These are wood based domestic burners, which can also run off of coal (with far more pollutants released into the atmosphere from the burning of coal over wood, although wood itself can release more contaminants into the atmosphere than many people realize). The other offending source would be vehicle fumes and emissions, with many areas of high traffic seeing larger concentrations of nitrogen dioxide (NO₂) building up, with areas of low elevation or surrounded by valleys or buildings being particularly susceptible, due to these ‘pollution sinks’ causing smoke and other fine particles to build up and find difficulty in being dispersed due to lack of winds at ground level. So, to summarize, the two biggest causes of pollution in Sheffield are the burning of wood or coal stoves and fireplaces, and the other being vehicular pollution.

What are some other pollutants found in the air around Sheffield?

Besides the aforementioned nitrogen dioxide building up in the air around areas of high traffic (as well as being emitted from burnt organic material), numerous other pollutants are released from these processes. These would include ones such as black carbon and volatile organic compounds (VOC’s), both of which are released from the burning of organic matter as well as fossil fuels, and usually under conditions where the combustion process is incomplete, such as one would find in a car engine or fireplace. Black carbon is a major component of soot, and has disastrous effects on human health when inhaled, due to its extremely small size as well as chemical structure.

Other pollutants released from wood burning stoves include sulfur dioxide (SO₂), which aside from being a harmful gas to inhale, is also the main contributor to acid rain. Carbon monoxide (CO) also finds itself being released, which aside from being an atmospheric pollutant, can oftentimes cause fatalities when it builds up in domestic areas, due to it being odorless and colorless thus making it known as a ‘silent killer’, although this is more common in malfunctioning gas burners than wood-based stoves. Others include dioxins and furans, a family of toxic materials that have carcinogenic properties as well as being highly susceptible to undergoing chemical bonding with other pollutants, thus creating more dangerous forms of PM2.5, all of which are highly undesirable for a population to be respiring.

When are the pollution levels in Sheffield at their worst?

Observing that data taken over 2019, Sheffield showed particularly elevated levels of pollution during the months of February, April and November, which came in with PM2.5 readings of 21.6 µg/m³, 23.8 µg/m³ and 15.6 µg/m³ respectively, making the month of April the most polluted of the entire year, with a reading that is nearly double that of the yearly average of 12.7 µg/m³.

Five months out of the year came in with a moderate rating (January, February, April, May and November) whilst March and December came in with ‘good’ ratings (PM2.5 readings of anywhere between 10 to 12 µg/m³). The rest of the year all came in with readings that were within the World Health organizations target goal of 0 to 10 µg/m³ of particulate matter in the air, with July being the cleanest at 8.3 µg/m³. This indicated that the months at the beginning and end of the year are worse in terms of levels of pollution, whilst the middle months (June to October) all showed the better air quality readings.

Are the pollution levels in Sheffield improving?

Going off readings of PM2.5 taken in years prior, it shows that Sheffield had a yearly average reading of 9.6 µg/m³ in 2017, putting it into the WHO’s target goal for year-round clean air. This was followed in 2018 by a prominent change of 12.8 µg/m³ as an average, bringing its rating up back into the moderate category. Following on to 2019, a very slightly improved (by a margin of 0.1 µg/m³) 12.7 µg/m³ was recorded, showing that since the year of 2017, the quality of air has decreased, indicating that there may be higher instances of smoke, haze and other forms of pollution tainting the air and skewing the readings. Preventative measures such as the reduction of wood burning stoves and prohibiting coal burning may go a long way in helping Sheffield to once again see yearly averages that fall into the WHO’s target goal for a cleaner quality of air, and move it out of its 5^th place position of most polluted cities in the United Kingdom.