Air Pollution Facts - What You Should Know

The main purpose of this page is to provide you with critical air pollution facts so that you can keep up to date with the latest research on where severe air pollution events most commonly occur around the world.

If you're planning to travel overseas, you need to be aware that most severe air pollution episodes are seasonal and so can be avoided. However, if you're planning to travel to Dhaka, which is the capital of Bangladesh, you can expect air pollution levels to be dangerously high throughout the whole year.

Here's some alarming air pollution facts about:

• Canada
• Kathmandu
• Mexico City (Yes this location is particularly bad. The people living
  here are loosing their sense of smell since smog levels are so high.)
• Japan
• Buenos Aires (Argentina)
• The London smog episode of 1952

Air pollution facts for Europe

The worst location in Europe for air pollution is located where the borders of Poland, Czech Republic and Germany meet.

This area is known as the "The Black Triangle" since this region is one of the most industrialised regions in all of Europe.

This region has considerable amounts of both acidic fog and rain events, that have severely damaged the forests.

You should definitely keep away from the Black Triangle if you suffer from any respiratory illness, since your symptoms will be exasperated if you stay here for even a short period of time.

Air pollution facts for China

This may not come as any surprise to you. Acid rain affects 38% of the Chinese cities. The main cities where acid rain occurs is Beijing, Shanghai as well as Guangzhou, Shanzhen and Hong Kong.

The Chinese people rely heavily on coal as their main source of energy consumption. When this coal is burned, PAH's as well as sulfur dioxide (SO₂) are produced. This SO₂ converts to sulfate (SO₄) when oxidised. The SO₄ is highly soluble, and that explains why it's the main cause of acid rain in China.

Acid rain is a major concern in China, particularly in the southern and eastern parts. The reason why acid rain isn't as bad over the northern parts of China is because the high proportion of carbonates (CO₃) in the dust clouds act to neutralise the SO₂ emissions in the area.

Air pollution facts for Beijing

Beijing is the capital of China and also China's second largest city. It had a population based on Dec 2007 estimates, of 17.4 million but as of January 2016, it has reached 21.5 million. Beijing has many air pollution problems due to the huge amount of traffic emissions coming from airports, railways, and vehicles. Dust storms frequently pass over Beijing during the spring (March, April and May) and havebeen getting worse since 1999. This dust mixes with the local air pollution, not only causing low visibility, but also causing severe respiratory problems in the general population.

Air pollution facts for Japan

The western coastline of Japan is subject to high levels of air pollutants that have arrived from the industrial parts of mainland China.

These types of pollutants are only common when the wind is blowing in from China. However, Japan does produce significant levels of home grown air pollutants in Tokyo, Sappora, Osaka and Kobe.

A number of studies have shown that the concentration of vehicle pollutants in the atmosphere over Japan is seasonal. Winter has the highest levels of vehicle pollutants and summer records the lowest levels of these types of pollutants. It's not that people drive less in summer. What happens is the sunlight converts the vehicle emissions to secondary air pollutants such as ozone and so the measured levels of primary vehicle pollutants are lower during the summer.

From the point of view of human health, vehicle emissions are quite dangerous when the concentrations are high. These types of pollutants produce polycyclic aromatic hydrocarbons (PAH's). PAH is a potent air pollutant and is classified as a possible carcinogen.

With that in mind, you should be aware Tokyo, Sappora, Osaka and Kobe all emit PAH's to varying degrees. However, PAH's are not only produced by vehicle emissions. They form due to the incomplete combustion of fossil fuels from burning coal, wood, as well as steel and iron industries. Okay, now that you know this, the worst region in Japan for PAH's is the industrial city of Fuji.

Highly industrial regions in Japan, like Fuji also act as sources of SO₂, which lead to acidic precipitation. I should also point out that vehicle emissions, such as NO_x also can produce acidic precipitation.

Please note: I have written another page about air pollution facts in Japan so hopefully this will help answer your questions.

Electric cars produce far less CO and hydrocarbons compared with conventional vehicles but other forms of air pollutants such as NO_x and CO₂ are emitted at the same rate.

Dust and air pollution facts

In recent decades, there has been an increased number of air pollutants being emitted to the atmosphere through both natural processes (i.e. dust storms, bush fires and volcanic ash) as well as from industrial and vehicle sources. Did you know that burning emissions from coal and vehicle exhausts have increased by about 4% per year since the 1970s in Asia? Did you also realise that these air pollutants are regularly transported thousands of kilometres downwind and this impacts the ecosystems and human health in the countries where it's deposited?

Here's some air pollution facts that may be interesting for you. The main natural air pollutant is mineral dust, which is commonly found in the arid regions of the world. This so-called benign dust can quickly be transformed into a massive dust cloud when the surface weather conditions are windy.

These dust storms cause airport closures in many countries across the Middle East and Asia. However, while this is extremely annoying if you're left waiting at the airport, there's a darker side to these dust storms.

A number of scientific studies have shown that dust storms are able to transport live fungus, mold, bacteria, viruses and even live locusts ten's of thousands of kilometres across oceans. Dust analysed from the Sahara desert shows that it carries with it specific bacteria that is dangerous to human health. If these dust particles are inhaled, you inevitably also inhale some of the bacteria.

There's some scientific evidence to suggest that meningitis outbreaks in North Africa are linked to the frequent occurrence of dust storms in that region.

Air pollution facts regarding the worst smog event the world has ever known

One of the worst severe air pollution events in the world wasn't caused by human activities. Instead, it occurred due to a volcanic eruption in Iceland, known as the Laki eruption. This volcano erupted on the 8th June 1783 and continued until 7th February 1784. It emitted 122 megatons of foul smelling acidic fog. This thick fog mostly consisted of sulfur dioxide (SO₂).

What you may find amazing about this particular fog is that it had the same acidity as stomach acid (pH ~ 1 - 2). This thick sulphurous fog covered large areas, stretching from the United Kingdom (UK) to the Middle East as well as from Scandinavia to Portugal. It's no wonder that most plant life died and so many farmers were forced to abandon their livelihood and hope that they wouldn't starve to death.

This air pollution was so severe that one quarter of Iceland's population perished and thousands of animals and people died elsewhere. Furthermore, many people died, not only because the air quality was so bad, but due to the lack of fresh food and clean drinking water.

What compounded the situation was the fact that the volcanic emissions produced extreme weather conditions. Generally, the winters and summers were much colder than usual in some areas. In particular, Alaska didn't receive any warmth during the summer of 1783 and much of the ground remained frozen and thus crops could not be grown. In contrast, parts of Europe were in the grip of severe heat waves throughout this time.

Seven air pollution facts that most people do not know:

1. Typhoons that hit Taiwan, Japan, and Hong Kong tend to produce widespread acidic rain. The typhoons draw in highly polluted air originating from south east China. This air becomes integrated into the typhoon circulation before falling to the ground with the rain.
   
   
2. Acid fog is even more potent than acid rain. There is now considerable evidence that shows that acidic fog leads to the decline of high-elevation forests that are located in south eastern Canada, eastern United States, south eastern China, Japan, eastern Russia and many parts of Europe. The majority of acidic fog events are due to emissions from heavy traffic and other industrial sources. However, some of the worst acidic fogs in the past occurred due to volcanic eruptions.
   
   
3. You can even experience high pollution levels in locations far away from any industrial area. For example, you would think that Mt Fuji in Japan has clean air, but numerous studies have shown that acidic cloud droplets frequently bath the forests near the summit of Mt Fuji. This occurs when polluted air is blown into the region from south eastern China and occasionally from the industrial regions of Japan. Another unlikely region that commonly receives acidic fog is the mountains of central Scandinavia.
   
   
4. Aerosol particles (dust, smoke, smog) that are of the size 0.1 - 1.0 µm (i.e. 1 µ = 1 x 10^-6 and the m stands for metres) are able to travel worldwide and extend throughout the whole of the troposphere if meteorological conditions are suitable. This particle size has the longest residence time since particles both smaller and larger than 0.1 - 1.0 µm tend to be quickly dispersed into the atmosphere or incorporated into another particle.
   
   
5. The city of Zaragoza, in NE Spain is subject to high levels of air pollution, more so during the winter months. However, these episodes of air pollution don't last as long as those in other European cities. The reason is that the local wind, known as "cierzo" is nearly always present to blow all the air pollution out of Zaragoza. Most other industrial parts of Europe, on the other hand, don't have the luxury of such an efficient natural air pollution removal system.
   
   
6. Increased levels of air pollution interferes with flower pollinators (such as bees). A number of studies have shown that when there's thick smog present, the scent of a flower is modified to such an extent that the pollinators aren't attracted to it. This has led to a decline in certain plant species in many industrial regions of the world.
   
   
7. Here's some additional air pollution facts you should bear in mind if you're planning to travel to Bangladesh. Dhaka, which is the capital city of Bangladesh, has some of the worst air pollution episodes out of any city in the world. It is a fast growing city with massive traffic congestion and high numbers of unregulated industries that are located in close proximity to the city. A majority of the pollutants are from SO₂, that leads to acidic precipitation and low visibility due to thick smog. Winter normally has the most severe air pollution episodes.

Ozone air pollution facts

High concentrations of surface ozone are common in most large cities throughout world, particularly on warm sunny days. Typically, surface ozone forms when traffic exhaust pollutants such as nitrogen oxides (NO_x) and volatile organic compounds (VOC's) react with sunlight.

This ozone is known to aggravate pre-existing respiratory illnesses such as asthma and bronchitis.

Severe ozone pollution episodes in Athens and Los Angeles are common in the summer months. Both these cities are surrounded by an ocean on one side and tall mountains on the other. When a sea breeze is advancing inland, it pushes all the ozone with it where it becomes trapped near the base of the impenetrable mountains.

If you happen to be living in this particular area, then it's highly likely you'll be suffering some form of eye and throat discomfort. At night, surface ozone levels drop since there's no sunlight and also due to the fact that the land breeze blows much of the smog back towards the coastal areas.

References

1. Gurjar BR, Butler TM, Lawrence MG and Lelieveld J. Evaluation of emissions and air quality in megacities. Atmospheric Environment. 2008;42:1593-1606.
   
   
2. Witiw MR and LaDochy S. Trends in fog frequencies in the Los Angeles Basin. Atmospheric Research. 2008;87:293-300.
   
   
3. Watanabe K, Takebe Y, Sode N, Igarashi Y, Takahashi H and Dokiya Y. Fog and rain water chemistry at Mt. Fuji: A case study during the September 2002 campaign. Atmospheric Research. 2006;82:652-662.
   
   
4. Zhang YX, Tao S. Seasonal variation of polycyclic aromatic hydrocarbons (PAHs) emissions in China. Environmental Pollution. 2008;156(3):657-663.
   
   
5. Shao M, Zhang YH, Zeng LM, Tang X, Zhang J, Zhong L and Wang B. Ground-level ozone in the Pearl River Delta and the roles of VOC and NOx in its production. Journal of Environmental Management. 2009;90(1):512-518.
   
   
6. Hopke PK, Cohen DD, Begum BA, et al. Urban air quality in the Asian region. Science of the Total Environment. 2008;404(1):103-112.
   
   
7. Callen MS, de la Cruz MT, Lopez JM, Murillo R, Navarro MV and Mastral AM. Long-range atmospheric transport and local pollution sources on PAH concentrations in a South European urban area. Fulfilling of the european directive. Water Air and Soil Pollution. 2008;190(1-4):271-285.
   
   
8. Blas M, Sobik M and Twarowski R. Changes of cloud water chemical composition in the Western Sudety Mountains, Poland. Atmospheric Research. 2008;87(3-4):224-231.
   
   
9. Wei LJ, Mosley-Thompson E, Gabrielli P, Thompson LG and Barbante C. Synchronous deposition of volcanic ash and sulfate aerosols over Greenland in 1783 from the Laki eruption (Iceland). Geophysical Research Letters 2008;35(16):L16501.

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