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Air-Quality

In the top 15% globally

The answer, my friend, is blowin’ in the wind
Bob Dylan, ‘Blowin’ in the wind

Of all the world’s reporting stations, St Helena’s air is in the top 15%

 

Air-Quality

Below: How do we know this? • Why is this? • What does this mean? • Even Jamestown? • Read More

How do we know this?

In 2016 NASA set up an AERONET site on St Helena, located at our Weather Station. The AERONET instruments measure air-quality - specifically the amount of dust and other particles in the air. Cleaner air has fewer particles. Our site is one of around 1,200 reporting sites around the globe.

NASA makes the data collected by all its AERONET sites available for download on the AERONET website. We were able to download the dataset AOD_Level15_Monthly_V3.tar.gz from aeronet.gsfc.nasa.gov/new_web/download_all_v3_aod.html. We then processed this data as follows:

  1. Amalgamate the data collected for all particulate sizes and all dates into a single, average ‘Pollution Index’ value for each site;

  2. Process the decimal value to give a simple integer;

  3. Rank these, smallest (cleanest air) to highest (most polluted air).

We then noted St Helena’s position in that list - 142 out of 1197 reporting stations. This puts St Helena at 12% - comfortably in the top 15% by air-quality.

We present below a table showing some selected locations and their pollution indexes, from our analysis:

Best stations

 

Worst Stations

Station

Pollution Index

 

Station

Pollution Index

South Pole

231

 

Bangkok, Thailand

7318

Dunedin, NZ

486

 

Kuwait

6895

Honolulu, Hawaii

498

 

New Delhi, India

6741

North Pole

502

 

Lahore, Pakistan

6121

Reykjavik, Alaska

541

 

Beijing, China

5545

St Helena

718

 

Hong Kong

4327

Lerwick, Scotland

742

 

Myanmar

4013

Edinburgh, Scotland

743

 

Taipei, Taiwan

3867

Denver, USA

759

 

Seoul, South Korea

3707

American Samoa, Pacific

789

 

Bahrain

3575

Helsinki, Finland

869

 

Cairo, Egypt

3488

Glasgow, Scotland

889

 

Mexico City, Mexico

3457

Monterey, California

908

 

Singapore

3393

Halifax, Nova Scotia

917

 

Kathmandu, Nepal

3304

Madrid, Spain

926

 

Dead Sea, Israel

3206

Cork, Ireland

967

 

Penang, Malaysia

2940

Tahiti, Pacific

998

 

Chiang Mai, Thailand

2916

Exeter, England

1029

 

Miami, Florida

2571

Barcelona, Spain

1114

 

Osaka, Japan

2417

Oxford, England

1177

 

Leicester, England

2200

Azores

1202

 

Munich, Germany

1978

Toronto, Canada

1238

 

Warsaw, Poland

1946

Maldives, Indian Ocean

1261

 

Brussels, Belgium

1919

Tenerife, Mediterranean

1285

 

Rio de Janeiro, Brazil

1853

Bermuda, West Atlantic

1350

 

Nairobi, Kenya

1808

Vienna, Austria

1354

 

Moscow, Russia

1715

Swakopmund, Namibia

1355

 

Rome, Italy

1628

London, England

1399

 

Athens, Greece

1606

Berlin, Germany

1410

 

Ascension Island

1564

The Hague, Holland

1451

 

Nicosia, Cyprus

1559

Paris, France

1465

 

Barbados, Caribbean

1529

Walvis Bay, Namibia

1474

 

Brasilia, Brazil

1474

Put another way, if the best reporting station (at the South Pole) scores 231, and the worst reporting station (Bangkok, Thailand) scores 7318, then St Helena has under 10% of the air pollution of Bangkok and only 3 times as much as the South Pole.

The AERONET equipment is positioned 434m above sea level at 15°56’32.64”W, 5°40’2.28”S.

Why is this?

Wind direction {1}
Wind direction{1}

As is explained on our Weather and climate page, the wind here blows almost exclusively from the SSE/SE (diagram, right). This means it passes up from the South Pole, clips the southern tip of Africa, then travels exclusively over the sea until it reaches St Helena. It picks up a small amount of pollution from Africa but apart from that it gains no pollutants.

St Helena itself adds little to the mix. There is no heavy industry here. The main local contributors to poor air quality are older vehicles (of which we have a few) and the diesel-powered Power Station in Ruperts. Apart from these we have nothing to significantly deteriorate our air-quality.

What does this mean?

Firstly it means that respiratory diseases are not a major issue on St Helena. But for a visitor to St Helena it means you can go out and about and fill your lungs with our clean, fresh air!

Even Jamestown?

Jamestown is a narrow, dry valley, and the hillsides combined with a lack of rain probably add a bit to the town’s air pollution, but has still possibly the best air-quality of any world Capital. Some older people who live ‘up-country’ do say they find Jamestown ‘polluted’, but then it all depends on what you are used to. For many years the editor of this website lived in London, UK which is so polluted that when you fly out of London Heathrow Airport you can see the dome of dirty air over the city. Jamestown has nothing on that!

Read More

Article: We Will Continue to Work Closely with NASA

By Hannah Durnford, published in the St Helena Sentinel 22nd September 2016{a}

Conducting checks
David Giles conducting checks with the MET Station Team

NASA Scientist, David Giles recently visited St Helena to launch an instrument under the AERONET Programme. The programme is an international network of automatic sun and sky scanning instruments which measure the aerosol optical depth and collect related aerosol characteristics.

The US National Aeronautics and Space Administration (NASA) contacted the island’s MET Office a few months ago and sent out equipment via Cape Town, which was forwarded to St Helena for the installation project. Meteorological Station Manager Lori Bennett told The Sentinel, We were delighted to facilitate David’s visit to St Helena. All that could have been accomplished in his short time was achieved.

There were connection issues at the beginning via the Sure Mobile FTP Network; however the device is now functioning as it should.

While David was on board the RMS he conducted presentations and discussions on the awareness of climate change. He also performed ship-based measurements in partnership with the flight overpasses carried out by the NASA P-3B Airborne Laboratory. He was able to pick up, via his handheld device, smoke particles from the recent Angolan forest fires.

The island’s MET Office hopes that they will continue to work with NASA even after this visit, We will continue to work closely with NASA and look forward to the possibility of installing additional global monitoring equipment in the future on the MET Site at Bottom Woods, Lori said.

Laugh at funny Air-Quality humour - LOL

Credits:
{a} South Atlantic Media Services Ltd (SAMS){2}

Footnotes:
{1} Showing the wind direction on each day of a year.{2} Reproduced for educational non-commercial use only; all copyrights are acknowledged.

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