|星期六, 1月 16|
对敏感人群不健康 137 美国 AQI
|星期日, 1月 17|
对敏感人群不健康 110 美国 AQI
|星期一, 1月 18|
对敏感人群不健康 125 美国 AQI
对敏感人群不健康 141 美国 AQI
|星期三, 1月 20|
中等 58 美国 AQI
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中等 67 美国 AQI
|星期五, 1月 22|
对敏感人群不健康 124 美国 AQI
|星期六, 1月 23|
不健康 198 美国 AQI
|星期日, 1月 24|
不健康 198 美国 AQI
Dubai is a city located in the United Arab Emirates, being the most populous city in the country and a major financial hub that is focused around exports and trade, tourism, real estate and other similar services, as well as its reserves of natural resources such as oil. This is something that has in more recent times been recognized as an unsustainable industry, despite its helping hand in the country (and Dubai’s) economic and population boom that occurred during the 70’s and onwards.
In regards to its pollution levels, Dubai saw itself coming in with a PM2.5 reading of 40.9 μg/m³ as a yearly average over 2019. This put it in the ‘unhealthy for sensitive groups’ bracket, which requires a PM2.5 reading of anywhere between 35.5 to 55.4 μg/m³ to be classed as such, and as the name implies, this poorness of air quality would be particularly dangerous to vulnerable portions of the population, with demographics such as young children, the elderly, pregnant mothers and the immunocompromised or ill being most at risk.
This reading of 40.9 μg/m³ was enough to place Dubai in 1st place out of all cities ranked in UAE over 2019 (coming in just ahead of Abu Dhabi), as well as being 222nd place out of all cities ranked worldwide. This is indicative that Dubai is suffering from some fair amounts of pollution issues, with an unsafe quality of air to breathe for much of the year. The reasons as to why Dubai is coming in with elevated levels of pollution will be discussed in short.
There are several factors that compound the pollution situation in Dubai, with meteorological conditions such as its extreme heat and high humidity during summer months assisting in trapping pollutants within the atmosphere, as well as the more pertinent manmade causes.
Some of these would include the high usage of personal vehicles, with Dubai being a city that requires a car or other vehicle in order to properly navigate its urban landscape. As such, vehicle ownership is extremely high and far more prevalent than the use of public transport is, leading to a large amount of pollution stemming from this source.
Cars and motorbikes would put out large amounts of noxious pollution, along with heavy duty vehicles such as trucks, lorries and buses all playing their part, often running on fossil fuels such as diesel and therefore having a far higher pollutive output than their non-diesel counterparts would.
Other causes of pollution include factories and industrial areas, as well as the city and whole country relying heavily on its natural resources of fossil fuels to provide much of its energy, although this is slowly changing in recent times due to the acknowledgement that it is an unsustainable practice.
Industrial sites such as desalinization plants (that make sea water drinkable) are in heavy use due to the massive increase in drinking water demand due to Dubai's population explosion. The widespread use of these exacts a large toll on pollutive output levels, causing the year round ambient readings to be higher than they should be. To reiterate, the main causes of pollution in Dubai are vehicular emissions as well as factories and other similar industries.
Observing the data taken over 2019, the months that came in with the highest readings of PM2.5 occurred during the summer season, which takes place between April and October. 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 is of particular danger when respired. Due to this, it is used as a major component in the calculation of overall levels of air quality, and will be used to discuss Dubai's most polluted times.
Air quality starts to decline during the aforementioned summer months, with the last ‘cleaner’ reading coming in over April with a number of 23.9 μg/m³. This then rises rapidly up to 44.1 μg/m³ in May, reaching a peak in June at 59 μg/m³, making June the most polluted month out of the entire year, sitting in the ‘unhealthy’ ratings bracket (55.5 to 150.4 μg/m³).
The months following this were equally as polluted, with these higher levels of pollution not abating until the end of October, when the PM2.5 levels fell from 54.2 μg/m³ (in October) to 21 μg/m³ in November, a marked difference that highlights just how prominent the rise in pollution is during the summer months.
In contrast to the previous question, as stated, the months that had the worst levels of pollution came exclusively during the summer months, with the extreme heat and high humidity causing pollution to accumulate within the city. High levels of sunlight mixed with pollution given out by vehicles can also cause dangerous pollutants such as ozone (O3) to form, with the various nitrogen oxides from exhaust fumes reacting under the high heat conditions to cause the aforementioned harmful pollutant.
In regards to when the air is at its very cleanest, February through to April showed some very promising signs of cleaner air quality, albeit with some data missing in January. The cleanest month of the year was February, with a PM2.5 reading of 18.7 μg/m³, classifying it in the lower end of the ‘moderate’ pollution ratings bracket. Other months with better qualities of air were also November and December, both of which fell into the moderate bracket.
As information for those who are breathing polluted air in Dubai, the chemical compounds or fine particulate matters that are most pertinent are ones such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), with nitrogen dioxide being the most prominent in the atmosphere due to its high release from vehicles, so much so that high levels of nitrogen dioxide often correlate directly with a larger volume of traffic.
Other pollutants would include those released from the combustion of fossil fuels, which would be black carbon (a major component in soot) as well as volatile organic compounds (VOC’s), with examples such as benzene, toluene, xylene and formaldehyde all being present.
All of these have highly detrimental effects on human health and are very easy to respire, due to their volatile nature making them a gas at much lower temperatures. Other ones of importance would include the previously mentioned ozone, as well as fine particulate matters such as finely ground silica dust from construction sites, which along with black carbon has carcinogenic properties when inhaled.