How megacities around the world are tackling their air pollution

From Delhi to Istanbul to Los Angeles, air pollution is a big issue, especially in the world's biggest cities. "It will decrease your lung function. It will increase asthma attacks.

It will increase hospital admission. . .

" ". . .

contributes to seven million deaths a year. " See all these pink dots? They show that in almost every major city in the world, the air is far dirtier than what the World Health Organization considers safe.

When we dove into the data, though, we found some surprisingly good news. In many megacities, the air is getting better. So, we wondered: What are these cities doing right, and can every place do this?

For this analysis, we looked at one measure of air pollution that's everywhere: PM 2. 5. "PM 2.

5. . .

" PM stands for "particulate matter", a mixture of solid particles and liquid droplets that are 2. 5 microns or less – much smaller than a human hair. This is only one possible type of air pollution, but people like Sophie Gumy from the WHO use it as an indicator for air pollution in general.

"Because this is a pollutant that can come from various different sources. And it's ubiquitous in the world, so there is literally no place in the world that is free of particulate matter. " And it's big cities that are often particularly polluted.

This problem has been well known for years. To find out whether anything has changed, we took a closer look at this database from the Swiss company IQAir, which shows average levels of PM 2. 5 for more than 7,000 cities over the past five years.

We put it all into a big Excel spreadsheet and checked that against a list of the world's biggest cities, those with more than 10 million people living in them. Of those 25 cities, it seems like the air has gotten better in almost all of them – even where levels are still high. "What we've seen is that on average about five percent improvement in air quality over the past few years.

" Zoe Chafe helps cities that want to tackle the air pollution problems. The causes are similar, even when their proportions vary. "Transportation emissions are often number one, not always.

And then also just generally electricity use, people cooking with solid fuels in their homes in some parts of the world, heating with solid fuels. Another major source of air pollution is from industrial sources, and then also from waste. " So here's what cities are doing to tackle these issues.

For many cities, changing how people move around can make a big difference. Here's Sophie Gumy from the WHO again: "There is a need, really a push, to really have cleaner vehicles, but also fewer vehicles, to really promote walking, cycling and providing also public transportation with electric vehicles. " Take Bangkok, for instance.

The city is working on expanding its – still limited – Skytrain and Metro services. And in the meantime, electric alternatives for the traditional combustion-engine TukTuks let people get around emission-free as well. Delhi is working on electrifying 80% of its bus fleet.

And even in Kolkata, sometimes called the "diesel capital of the world", alternatives like this electric scooter service are starting up. The next step, Zoe Chafe says, can be introducing so-called "low-emission zones" "Cities that are restricting emissions in a certain part of their city both to improve air quality, but also to improve quality of life. " This might mean only allowing cleaner cars to enter, or no cars at all.

And it might mean transforming streets to make more room for pedestrians or bicyclists. "This is something that's resonating across all regions of the world right now, and it's really exciting. " From Times Square in New York City being converted to a pedestrian area, to reducing traffic in Kampala or Belo Horizonte, to more bike lanes in Paris or Pune: cities everywhere are experimenting with a different kind of urban design.

Transport is not the only area cities must tackle. Delhi's action plan against air pollution also focuses on industry: by measuring and reducing the dust from construction sites, and having more industries shift to cleaner fuels and more efficient techniques, like converting traditional brick kilns to zigzag kilns. This is something a lot of cities are doing, like here in Lahore, Pakistan.

The method still uses coal, but much less of it, and it traps more of the particular matter inside the kiln, lowering its emissions. One reason for Delhi's slightly better air these days might be that in 2018, the city shut down the Badarpur coal power plant, which was responsible for around ten percent of the city's particulate matter air pollution alone. One area where progress is still slow is waste.

"So there are these solid waste management bylaws from 2016. They are still not implemented. " Bhavreen Kandhari has been advocating for cleaner air for more than 20 years.

She founded the mothers' activist group Warrior Moms, who campaign against air pollution by petitioning the government and courts throughout India. She says even when the right policies are there, the government often doesn't follow through. "We do not segregate our waste at source, and mostly it's all mixed, and that is what is making those huge landfills, and the mixed waste is incinerated in the middle of a city.

" Without organized waste collection, burning is often the only option for getting rid of unwanted materials, causing toxic smoke full of harmful particulate matter that can stretch for miles. So preventing waste, as well as collecting and disposing of it better has to be part of any city's plan to curb air pollution. When policies are implemented thoroughly, that can have a big impact.

Take Beijing, for instance. A decade ago it consistently made headlines for its toxic smog cover. But in the last few years it has massively reduced its pollution levels.

And it's not just Beijing: Many of China's megacities have improved a lot recently. This is the result of what the Chinese government calls a "war on air pollution" that focused on all of the causes we've already mentioned, but not least on energy, on how people cook, and heat their homes. The city of Beijing imposed tight limits on emissions from boilers used in people's homes and subsidized anyone who wanted to upgrade their coal-fired boiler to natural gas – which is still a fossil fuel but produces much less particulate matter – or to electricity which could be produced by renewables.

Studies show that twenty percent of the reduction in Beijing's pollution just came from renovating these coal-fired boilers. Outside of China as well, countries around the world are investing in renewable energy, phasing out coal from the energy supply in favour of solar, wind and others. Countries like Poland are also getting rid of their coal and wood fired stoves.

And Seoul in South Korea, which already swapped coal heaters for gas back in the 1990s, is now discussing the switch to more eco-friendly heat pumps. For cooking, stoves fired with wood or kerosene are still the only option in many parts of the world, especially in rural areas without access to electricity. But projects from Pakistan to Rwanda to the Himalayas are introducing cleaner stove models to those regions as well.

Whether and how fast cities can implement change comes down to a few things. And the first hurdle is better data. Take Lahore in Pakistan.

It regularly tops lists of the world's most polluted cities. According to the data, it looks like it has improved, at least a little, but it's hard to say whether any actual change has happened. "We haven't really seen any trends that would explain why the numbers are going down.

So I think it's just that the quality of data improved. " This is Abid Omar. In 2016, he founded the Pakistan Air Quality Initiative.

Which is a community initiative where like-minded individuals, corporations, organizations have come together with low-cost monitors and are providing that data publicly on the internet on various platforms. And that data is what is driving awareness. In Pakistan, there are very few air quality monitors set up by the government.

This makes it hard to judge whether things are actually getting better. Thanks to Abid's initiative, though, there are now more than a dozen sensors in Lahore alone showing the current air pollution levels, making it harder for governments and citizens to ignore the issue. And better monitoring systems have sprung up everywhere in the past few years.

"Cities are increasing their ability to monitor their air quality and this is something that is extremely important, a very positive trend from our perspective. " Then there's the question of money. "Beijing was able to put a huge amount of investment into the air quality problem.

And that is the key question for a lot of other cities right now: Do they have the money to invest to make such a step change in their air quality? " And last but not least, there's a political hurdle: Collaboration. "So if you imagine air flowing together over parts of the world, that's what we call an air shed.

It doesn't respect political boundaries. And so in a place like Delhi, it's extremely important that neighbouring cities and jurisdictions work together on their common problem. " Crop stubble burning brings intense smog to northern India, including Delhi, every year after the harvest season.

And the same problem happens, for example, in Cairo or across Indonesia, where smoke clouds can reach so far they affect the air in Singapore and parts of Malaysia. So cities, regions and countries will have to work together to change. "Because if what we have at the heart of the matter is the health of the people living in a city, it doesn't really matter where the air pollution is coming from.

It's extremely important that it's reduced. " So air pollution is still a huge issue. Big cities all over the world are pretty far from what the WHO considers safe, which would be below five micrograms per cubic meter of air.

But it can get better. "So that's why I tell people when they get so disappointed, I say: it's taken me decades, you know, for us, people like us, to be fighting this here in the courts and coming such a long way. Changes happen.

Social changes are never easy. " And even when really good air is far away, any change helps. "Any reduction in air pollution is good for health.

Any small reduction is good. " What's more is that the things that clean up air are also good for combating climate change, which is likewise fueled by emissions from burning waste and fossil fuels. What would you like your city to do to clean up your air?

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