A map of London's most toxic breathing spots
Air pollution is up to five times over the EU limit in these Central London hotspots.
- Dirty air is an invisible killer, but an effective one.
- More than 9,000 people die prematurely in London each year due to air pollution, a recent study estimates.
- This map visualizes the worst places to breathe in Central London.
The Great Smog of 1952
London used to be famous for its 'pea-soupers': combinations of smoke and fog caused by burning coal for power and heating.
All that changed after the Great Smog of 1952, when weather conditions created a particularly dense and persistent layer of pollution. For a number of days, visibility was reduced to as little as one foot, making traffic impossible. The fog even crept indoors, leading to cancellations of theater and film showings. The episode wasn't just disruptive and disturbing, but also deadly. According to one estimate, it directly and indirectly killed up to 12,000 Londoners.
Invisible, but still deadly
London Mayor Sadiq Khan.
Image: MONEY SHARMA/AFP/Getty Images
After the shock of the Great Smog, the UK cleaned up its act, legislating to replace open coal fires with less polluting alternatives. London Mayor Sadiq Khan is hoping for a repeat of the movement that eradicated London's smog epidemic, but now for its invisible variety.
The air in London is "filthy, toxic," says Khan. In fact, poor air quality in the British capital is a "public health crisis". The city's poor air quality is linked not just to thousands of premature deaths each year, but also to a range of illnesses including asthma, heart disease and dementia. Children growing up in areas with high levels of air pollution may develop stunted lungs with up to 10% less capacity than normal.
ULEZ phases 1 and 2, and LEZ
Image: Transport for London
Khan has led a very active campaign for better air quality since his election as London Mayor in 2016. Some of the measures recently decided:
- Transport for London has introduced 2,600 diesel-electric hybrid buses, which is said to reduce emissions by up to 40%.
- Mr Khan has pledged to spend £800 million on air quality over a five-year period.
- Uber fares will rise by 15p (20¢) to help drivers buy electric cars.
- Since the start of 2018, all new single-decker buses are zero-emission and all new taxis must be hybrid or electric.
- Mr Khan has added a T-charge on the most toxic vehicles entering the city. On 8 April, the T-charge will be replaced by an Ultra-Low Emission Zone (ULEZ), contiguous with the Congestion Charge Zone.
- The ULEZ is designed to reduce emissions of nitrogen oxide and particulate matter by charging vehicles who don't meet stringent exhaust emission standards.
- By October 2020, a Low-Emission Zone (LEZ), applicable to heavy commercial vehicles, will cover most of Greater London.
- By October 2021, the ULEZ will expand to cover a greater part of Central London.
Central London's worst places for breathing
Heathrow (bottom left on the overview map) is another pollution hotspot
What worries experts is that despite considerable efforts already made, levels of air pollution stubbornly refuse to recede – and remain alarmingly high in locations where traffic flows converge.
It's not something you'd think of, given our atmosphere's fluctuating nature, but air pollution hotspots can be extremely local – as the above map demonstrates.
One important lesson for all Londoners: Don't inhale at Marble Arch! Levels of nitrogen dioxide (NO2) are five times the EU norm – the highest in the city. Traffic permitting, quickly cross Cumberland Gate to Speakers' Corner and further into Hyde Park, where levels sink back to a 'permissible' 40 milligrams per cubic meter. Now you can inhale!
Almost as bad: Tower Hill (4.6 times the EU norm) and Marylebone Road (4 times; go to nearby Regent's Park for relief).
Also quite bad: the Strand (3.9), Piccadilly Circus (3.8), and Hyde Park Corner (also 3.8), Victoria (3.7) and Knightsbridge (3.5), the dirty trio just south of Hyde Park.
Elephant & Castle is the only pollution hotspot below the Thames and, perhaps because it's relatively isolated from other black spots, also the one with the lowest multiplication factor (2.8 times the maximum level).
On the larger map, the whole of Central London, including its relatively NO2-free parks, still shows up as more polluted than the outlying areas. Two exceptions flare up red: busy traffic arteries; and Heathrow Airport (in the bottom left corner).
Traffic congestion on London's Great Portland Street
Image: Mike Malone, CC BY SA 4.0
So why is Central London's air pollution problem so persistent? In part, this is because the need for individual transport in cars seems to be inelastic. For example, the Congestion Charge has slashed the number of vehicles entering Central London by 30%, but the number of (CC-exempt) private-hire vehicles entering that zone has quadrupled over the same period.
Cycling has really taken off in London. But despite all pro-cycling measures, a wide range of other transport options and car-dissuading measures, central London is still a very congested place. Average traffic speeds on weekdays has declined to 8 miles (13 km) per hour – fittingly medieval speeds, as the road network was largely designed in medieval times.
Narrow streets between high buildings, filled to capacity with slow-moving traffic are a textbook recipe for semi-permanent high levels air pollution.
The large share of diesel vehicles on London's streets only increases the problem. Diesel vehicles emit lower levels of carbon dioxide (CO2) than petrol cars, which is why their introduction was promoted by European governments.
However, diesels emit higher levels of the highly toxic nitrogen dioxide (NO2) than initial lab tests indicated. Which is why they're being phased out now.
As bad as Delhi, worse than New York
By some measures, London's air quality is almost as bad as New Delhi's.
Image: Sanchit Khanna/Hindustan Times via Getty Images
By some measures, especially NO2, London's air pollution is nearly as bad as big Asian cities such as Beijing or New Delhi, and much worse than other developed cities such as New York and Madrid.
The UK is bound to meet pollution limits as set down in the National Air Quality objectives and by EU directives, for example for particulate matter and nitrogen dioxide.
- Particulate matter (PM2.5) consists of tiny particles less than 2.5 micrometres in diameter emitted by combustion engines. Exposure to PM2.5 raises the mortality risk of cardiovascular diseases. The target for PM2.5 by 2020 is 25 µg/m3. All of London currently scores higher, with most areas at double that level.
- Mainly emitted by diesel engines, NO2 irritates the respiratory system and aggravates asthma and other pre-existing conditions. NO2 also reacts with other gases to form acid rain. The limit for NO2 is 40 µg/m3, and NO2 levels must not exceed 200 µg/m3 more than 18 times a year. Last year, London hit that figure before January was over.
Google joins fight against air pollution
Elephant & Castle, London.
Image: laszlo-photo, CC BY SA 2.0
Studies predict London's air pollution will remain above legal limits until 2025. Sadiq Khan – himself an asthma sufferer – is working to make London's air cleaner by measures great and small. Earlier this week, he announced that two of Google's Street View cars will be carrying air quality sensors when mapping the streets of London
Over the course of a year, the two cars will take air quality readings every 30 metres in order to identify areas of London with dangerous levels of air pollution that might be missed by the network of fixed sensors. An additional 100 of those fixed sensors will be installed near sensitive locations and known pollution hotspots, doubling the network's density.
It's all part of Breathe London, a scheme to map the British capital's air pollution in real time. Breathe London will be the world's largest air quality monitoring network, said Mr Khan, launching the scheme at Charlotte Sharman Primary School in the London borough of Southwark.
Up to 30% of the school's pupils are said to be asthma sufferers. Charlotte Sharman is close to Elephant & Castle, as the above map shows, one of Central London's air pollution hotspots.
Strange Maps #956
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Researchers documented the most common negative side effects of smoking weed, and who might be most susceptible.
- A team of researchers identified a total of 26 possible adverse reactions to cannabis use.
- Coughing fits, anxiety, and paranoia are among the top three most common adverse reactions to smoking weed.
- It was the people who smoke on a less frequent basis who were more likely to have had the bad experiences.
The most common adverse effects of pot<p>As it turns out, coughing fits are among the top three most common adverse reactions to cannabis use, along with anxiety and paranoia, according to a new study published in the <em>Journal</em><a href="https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-019-0013-x" target="_blank"><em> of Cannabis Research</em></a>. </p><p>Now that weed is legal in the state, a team of researchers at Washington State University sought to document potential negative reactions to cannabis in order to paint a detailed picture of the effects of smoking weed for newbies. The authors surveyed more than 1,500 college students on the specific type and frequency of adverse reactions they had experienced while using pot. Additionally, the students in the study were surveyed about their demographics, personality traits, reasons for using cannabis and their use patterns. </p><p>Despite marijuana's <a href="https://bigthink.com/sex-relationships/marijuana-sex" target="_self">numerous benefits</a>, the team identified a total of <a href="https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-019-0013-x/tables/2" target="_blank">26 possible adverse reactions to</a> the drug. More than half of the study participants reported having coughing fits along with anxiety and/or paranoia while using cannabis. The most frequently occuring of these were the coughing fits, along with chest/lung discomfort and body humming. A subset of the study group reported these reactions occurring around 30–40% of the time they were using pot. On the flip side, the three <em>least</em>-commonly reported reactions to cannabis use were fainting, visual hallucinations and cold sweats. </p><p>"There's been surprisingly little research on the prevalence or frequency of various adverse reactions to cannabis and almost no research trying to predict who is more likely to experience these types of adverse reactions," <a href="https://news.wsu.edu/2020/03/30/new-research-sheds-light-potentially-negative-effects-cannabis/" target="_blank">said Carrie Cuttler</a>, assistant professor of psychology and an author on the paper, according to WSU News. "With the legalization of cannabis in Washington and 10 other states, we thought it would be important to document some of this information so that more novice users would have a better sense of what types of adverse reactions they may experience if they use cannabis."</p><p>The most distressing of the 26 negative reactions were panic attacks, fainting, and vomiting. Yet, the survey data suggested that cannabis users generally do not find even acute adverse reactions to cannabis to be severely distressing.</p>
What causes a bad reaction?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjkwOTEwOC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYyNTQ5MDQ2Mn0.S2Pkbh3VAgB4Gk5tkavamMv0_4t76dg65yGWpCHG17U/img.jpg?width=1245&coordinates=0%2C1872%2C0%2C1252&height=700" id="dee45" class="rm-shortcode" data-rm-shortcode-id="df6e30ecae156ba0012f4773a374800c" data-rm-shortcode-name="rebelmouse-image" />
But most city dwellers weren't seeing the science — they were seeing something out of Blade Runner.
On Sept. 9, many West Coast residents looked out their windows and witnessed a post-apocalyptic landscape: silhouetted cars, buildings and people bathed in an overpowering orange light that looked like a jacked-up sunset.
A study finds 1.8 billion trees and shrubs in the Sahara desert.
- AI analysis of satellite images sees trees and shrubs where human eyes can't.
- At the western edge of the Sahara is more significant vegetation than previously suspected.
- Machine learning trained to recognize trees completed the detailed study in hours.
Why this matters<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2MDQ1OC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzOTkyODg5NX0.O3S2DRTyAxh-JZqxGKj9KkC6ndZAloEh4hKhpcyeFDQ/img.jpg?width=980" id="3770d" class="rm-shortcode" data-rm-shortcode-id="3c27b79d4c0600fb6ebb82e650cabec0" data-rm-shortcode-name="rebelmouse-image" />
Area in which trees were located
Credit: University of Copenhagen<p>As important as trees are in fighting climate change, scientists need to know what trees there are, and where, and the study's finding represents a significant addition to the global tree inventory.</p><p>The vegetation Brandt and his colleagues have identified is in the Western Sahara, a region of about 1.3 million square kilometers that includes the desert, <a href="https://en.wikipedia.org/wiki/Sahel" target="_blank">the Sahel</a>, and the <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/subhumid-zones" target="_blank" rel="noopener noreferrer">sub-humid zones</a> of West Africa.</p><p>These trees and shrubs have been left out of previous tabulations of carbon-processing worldwide forests. Says Brandt, "Trees outside of forested areas are usually not included in climate models, and we know very little about their carbon stocks. They are basically a white spot on maps and an unknown component in the global carbon cycle."</p><p>In addition to being valuable climate-change information, the research can help facilitate strategic development of the region in which the vegetation grows due to a greater understanding of local ecosystems.</p>
Trained for trees<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDU2MDQ3MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNTk5NTI3NH0.fR-n1I2DHBIRPLvXv4g0PVM8ciZwSLWorBUUw2wc-Vk/img.jpg?width=980" id="e02c0" class="rm-shortcode" data-rm-shortcode-id="79955b13661dca8b6e19007935129af1" data-rm-shortcode-name="rebelmouse-image" />
Credit: Martin Brandt/University of Copenhagen<p>There's been an assumption that there's hardly enough vegetation outside of forested areas to be worth counting in areas such as this one. As a result the study represents the first time a significant number of trees — likely in the hundreds of millions when shrubs are subtracted from the overall figure — have been catalogued in the drylands region.</p><p>Members of the university's Department of Computer Science trained a machine-learning module to recognize trees by feeding it thousands of pictures of them. This training left the AI be capable of spotting trees in the tiny details of satellite images supplied by NASA. The task took the AI just hours — it would take a human years to perform an equivalent analysis.</p><p>"This technology has enormous potential when it comes to documenting changes on a global scale and ultimately, in contributing towards global climate goals," says co-author Christian Igel. "It is a motivation for us to develop this type of beneficial artificial intelligence."</p><p>"Indeed," says Brandt says, "I think it marks the beginning of a new scientific era."</p>
Looking ahead and beyond<p>The researchers hope to further refine their AI to provide a more detailed accounting of the trees it identifies in satellite photos.</p><p>The study's senior author, Rasmus Fensholt, says, "we are also interested in using satellites to determine tree species, as tree types are significant in relation to their value to local populations who use wood resources as part of their livelihoods. Trees and their fruit are consumed by both livestock and humans, and when preserved in the fields, trees have a positive effect on crop yields because they improve the balance of water and nutrients."</p><p>Ahead is an expansion of the team's tree hunt to a larger area of Africa, with the long-term goal being the creation of a more comprehensive and accurate global database of trees that grow beyond the boundaries of forests.</p>
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