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The war on smog

Charles Carter looks at the latest initiatives to tackle air pollution and one of its biggest causes.


Bangkok experienced some of its worst-ever air pollution in January. Over 400 schools were forced to shut due to the toxic air, and the government took to seeding clouds in an attempt to clear away the smog.


There must be a ‘smarter’, more preventative way for cities to deal with air pollution because Bangkok is not alone in grappling with the issue – nine out of ten people on the planet breathe air that contains high levels of pollutants, and polluted air kills seven million people a year.


I’m currently breathing a moped-spiked Ho Chi Minh City variety. Sadly, face masks have almost become a fashion accessory here – plain, hospital-style is so 90s! But even then, these masks are totally useless unless they fit well, researchers say.


Global deaths from air pollution (Source: WHO)
Global deaths from air pollution (Source: WHO)

Cause and effect


Outdoor air pollution is linked to heart disease, strokes, lung cancer and respiratory diseases.


The most toxic pollutants are Particulate Matter (PM), Ozone (O3) and Nitrogen Dioxide (NO2). Ultra-fine Particulate Matter (PM) can become lodged in your lungs or brain and cause disease.


Researchers have calculated that breathing in polluted air on a bad day in Beijing is equivalent to smoking 25 cigarettes per day.


Source: Berkeley Earth
Source: Berkeley Earth

The weighting of emission sources is different in each city. For example, the major source of NOx emissions in Greater London is road transport (50 per cent) followed by domestic gas use (12 per cent), whereas in Delhi it’s industry (52 per cent) then transport at 36 per cent.


It’s clear that as well as being a leading source of greenhouse gas emissions, the transport sector is responsible for a large proportion of urban air pollution, alongside factories and the burning of agricultural and household waste.


According to the World Health Organization, road transport is responsible for up to 30 per cent of particulate emissions in European cities, and up to 50 per cent in OECD countries.


Air pollution is arguably transport’s biggest problem.


Sources of air pollution (Source: WHO)
Sources of air pollution (Source: WHO)

A growing problem


The problem is only set to get worse too. With rapid urbanisation, more and more people will breathe in lethal air in the future.


“We wouldn’t drink dirty water. We wouldn’t eat food that had gone off if we knew it would have an impact on our health, so why do we put up with breathing dirty air?”, Prof. Kelly, Director of Environmental Research Group at King’s College London, said in a lecture in 2018.


The good news is that awareness is growing and authorities are starting to take action – they have to.


The good news is that awareness is growing and authorities are starting to take action – they have to.


In general, cities tackle the issue through a toolkit of measures, including a push towards public transport and cleaner vehicles, separating vehicles and pedestrian areas, reducing congestion through advanced traffic management systems, car bans and longer-term better urban planning.


Cities are also increasingly leveraging the latest IoT technologies to help monitor, understand and improve air quality.


Knowledge is power


You can’t manage what you can’t measure. With this in mind, many cities are ramping up efforts to monitor air quality and disseminate the information to their citizens in real-time – often through the use of emerging low-cost sensor technology.


Helsinki’s HOPE project, announced in late 2018, aims to leverage 5G to monitor air quality in real-time and develop a new air quality index.


“Our sensor network is being expanded and developed, which will help us to better understand the spatial variation in air quality,” said Outi Väkevä, Air Quality Expert, Helsinki Region Environmental Services Authority.


Helsinki already has live air quality displays on its public transport system as part of the Helsinki Air Quality Testbed (HAQT) project. Fed by data from 20 sensors, passengers can adjust their journey to avoid polluted areas, although more granularity and wider coverage are needed.


Rheibek commented: “We have seen from research that air pollution is not evenly distributed in space or time. Providing the public with real-time information on these hotspots could help to reduce exposure.”


Similarly, the Breathe London project is due to launch an online ‘air pollution heat-map’ shortly. The project is harnessing data from a 200-strong fixed-sensor network, as well as using mobile sensors on Google’s Street View cars. London also launches its Ultra Low Emission Zone next month.


Improved high-density monitoring could enable advanced traffic management systems to optimise the network on the fly to minimise air pollution. In 2018, Project ACCRA generated dynamic geo-fences around pollution hotspots in Leeds and pushed them to vehicles in real-time.



It is estimated that vehicle-to-traffic signal communications which enable real-time, in-car prompts could reduce emissions by up to 20 per cent. Birmingham is currently trialling such a solution in its Greenwave project.


The private sector is also realising the public’s need for air pollution information. AirVisual, for example, provides real-time and forecast air quality information online for cities across the world. Breezeometer offers a similar service.


Wearable air quality sensors that measure concentrations of pollutants in real-time have also been launched in recent years.


Examples include Flow, by plume labs and ATMO TUBE.


ATMO’s second model launches in April this year, with the ability to measure particulate matter as well as harmful gases.


Building trust in data


Obtaining reliable, granular and spatially comprehensive air pollution data is a significant challenge, though.


Dr Christopher Rushton, Senior Technologist at the UK’s Transport Systems Catapult (TSC), explained: “Current methodologies for air quality monitoring allow cities to meet legal obligations but not to measure at a granular level. Emerging low-cost sensors integrated with smart city technology offer the opportunity to change this. Validating these measurements in-situ will go a significant way to breaking down the barriers for implementation.”


Although there have been studies to assess the performance of low-cost air pollution sensors, such as one by the United States Environmental Protection Agency, a more rapid, standardised approach is needed to keep pace with technology and ensure the public can rely on the data.


Recent comments from the government of Cambodia questioning the veracity of online air quality data also highlight the need for more consensus to build trust in sensor information.




It’s encouraging that some cities are starting to see good results in tackling air pollution.


In 1992, Mexico City was the most polluted city on the planet. By 2016, it had slashed air pollution in half compared with the1980s. Measures included removing lead from gasoline, implementing catalytic converters in cars, reducing sulfur content in diesel fuel, substituting oil in industry and power plants with natural gas, reformulating liquefied petroleum gas for cooking and heating and implementing a “no driving day (Hoy No Circula)” rule. The challenge is ongoing and the city continues to look at new ways to reduce air pollution further.


One of the biggest concerns about air pollution is its impact on young people. In late 2018, Unicef said that the UK’s children are being denied the basic human right to clean air. Some schools are helping to address the challenge head-on.


Ruth Calderwood, Air Quality Manager for the City of London Corporation, said: “We have collaborated with Sir John Cass’s Foundation Primary School to monitor and develop solutions to tackle the problem."


The measures included adding ‘air quality plants’ and filtration units, widening pavements and reducing traffic. In June 2018, NO2 measures around the site fell below the legal limit for the first time since monitoring began in 2003.


A recent pilot project by Siemens Mobility successfully cut carbon and nitrogen emissions in congested areas of Munich.


A recent pilot project by Siemens Mobility successfully cut carbon and nitrogen emissions in congested areas of Munich.


Using real-time sensor data, Hawa Dawa provided pollution forecasts to Siemens Mobility’s Intelligent Traffic Systems (ITS) Digital Lab in Munich, where data scientists and traffic management experts analysed the data together with anonymised trip data from ryd (a platform by ThinxNet) to predict individual routes and suggest eco-friendly alternatives.


The results found that 35 to 40 per cent of drivers were willing to re-route when they were provided alternative suggestions through ryd.


The one-month trial, which launched in November 2018, included 1,600 drivers and delivered savings of 83 kg of CO2 and 114 g of NOx. Drivers also reduced their distance travelled by 633 km overall.


Gamification was used to incentivise users to take the alternate routes. The most eco-friendly drivers received ryd points which could later be converted into items such as Amazon vouchers.


No silver bullet


It’s fundamental that cities find new ways to communicate the complex subject of air pollution more clearly to make sure all stakeholders get it.


While India and China look to air purification technology to tackle the symptoms today, the jury is out on whether this will work and even if it does, it isn’t a viable long-term solution.


Governments, cities and the private sector must target root causes.


Many cities are pushing to up the usage of electric mobility to improve air quality. Bangarlaru, for example, in the Indian state of Karnataka, announced in February that 50 per cent of all Government vehicles will be electric by 2019, in addition to procuring 6,000 electric buses.


However, full EV penetration of global passenger car fleet is predicted to be many decades away (between 12 per cent and 47 per cent by 2040). And tyre dust is still likely to be an issue.


It’s clear that a mix of state-of-the-art monitoring technology and data analytics; bold initiatives targeting industry, agriculture and households; and green modal shift in transport are needed in parallel to EV growth.


As with most smart city initiatives, collaboration will also be key.


C40 launched its Air Quality Network (C40AQN) in 2018 to facilitate peer-to-peer information sharing across 30 cities, including best practice, to help cities manage air pollution better. It’s led by London and Bengalaru


“There needs to be greater alignment of city strategies on climate action and air quality management to produce further co-benefits”, Iyad Rheibek, Head of Air Quality, C40, said.


“Cities could focus on reducing air pollution which has immediate public health benefits, as well as longer-term climate advantages, he added.


Bring it on. I want to retire the face mask I’ve just purchased to the back of the wardrobe of history. ASAP.


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