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Ambient Particulate Air Pollution and Daily Mortality in 652 Cities

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Hong Kong can create its own smog, researchers say

Scientists from Hong Kong and Macau found one day in which pollutants were formed when dirty air was not blowing from the north

Smoggy days are often blamed on regional pollution and weather, but at least one recent scientific study has shown that the city can, under the right conditions, “form its own smog”.

The study by Hong Kong and Macau air scientists argued that a rapid build-up of particulate matter in the air – a key component of smog – was possible even in the absence of northerly winds that can transport pollutants from afar.

The evidence boiled down to at least one particular sunny September day in Hong Kong in which a “land-sea breeze” pattern formed along with weak winds far below average speeds.

The scientists observed a rapid rise of photochemical activity during mid-afternoon, in which ozone and nitrogen dioxide skyrocketed along with increasing sunshine.

“It is clear that there was a rapid increase in particulate matter (PM) concentration on this day when we were not really affected by external meteorological conditions. It’s not easy to argue in this case that winds were blowing PM to Hong Kong from the region ,” said co-author Professor Chan Chak-keung, dean of City University’s school of energy and environment.

The culprits, he said, were most likely local sources such as vehicles or industrial emissions, which contain nitrogen oxides and volatile organic compounds. The latter pollutant is also found in products such as organic solvents, paints and printer inks.

Chan’s team investigated “episodes” – days with high PM concentrations – in one-month periods in each of the four seasons from 2011 to 2012 at the University of Science and Technology’s air quality research supersite.

Other episodes across the seasons were also observed with high local photochemical activity, but those days also came under the influence of transported air from the north, making it less clear what was actually local or regional.

The paper was published in scientific journal Atmospheric Chemistry and Physics in November.

“Of course, regional sources play a role but [this research] shows that under the right conditions, PM can build up and Hong Kong can form its own photochemical smog.”

Photochemical smog is created when nitrogen oxides react with volatile organic compounds in the air under sunlight. It leads to the formation of ozone. This hazardous pollutant facilitates the formation of the tiny particles, small enough to be inhaled deep into the lungs and even into the bloodstream.

The particulate matter in the air lowers visibility, turning the sky smoggy and gives it a lurid orange tint at dusk.

The Environmental Protection Department usually points to meteorological influences such as northeast monsoons when the air quality health index hits “very high” health risk levels.

During a bout of high pollution last Thursday, it said: “Hong Kong is being affected by an airstream with higher background pollutant concentrations. The light wind hinders effective dispersion of air pollutants.”

It added that the formation of ozone and fine particulates during the daytime resulted in high pollution in the region.

Chan said most smoggy days were doubtless a result of regional factors or pollution. But he said the study’s findings warranted more research on how PM was formed and pinpointing its sources.

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Finland: 1,600 early deaths every year due to air pollution

Air pollution is estimated to cause some 1,600 premature deaths in Finland every year, says a new report from the Environment Ministry. Deaths caused by air pollution shorten the lifetime of the individuals by an average of 16 years.

Taken across the entire population, this means that the life expectancy of Finns is shortened by an average of over five months due to air pollution.

Most of the health damage is caused by tiny particles (PM) or by nitrogen oxides.

About half of the PM concentrations in Finland emanates from emissions from outside the country, while the other half comes from domestic emission sources, primarily from small-scale wood burning (46%), other energy production (16%), traffic exhaust gases (12%), street dust (10%), peat production (9%), and industry (7%).

Source: Environment ministry press release, 13 April 2016

Smog data shows 92 per cent breathe in unhealthy air

China’s pollution on Google Maps: Smog data shows 92 per cent breathe in unhealthy air … but how does Hong Kong fare?

James Griffiths

A map of pollution levels across China, as of September 3, 2015.

Google may be blocked for Chinese users, but that hasn’t stopped scientists from using the US internet giant’s services to help map China’s pollution problem [1].

Scientists working at the University of California Berkeley and Nanjing University previously mapped hourly pollution data from over 1,500 sites across China – including Hong Kong – to produce a comprehensive smog map of the country’s heavily populated eastern provinces.

“The greatest pollution occurs in the east [of the country], but significant levels are widespread across northern and central China and are not limited to major cities or geological basins,” Robert Rohde and Richard Muller wrote in their paper [2], published in the journal Plos One.

During the period covered by the scientists’ paper, from April to August 2014, 92 per cent of the population of China experienced at least 120 hours of unhealthy air (according to US environmental protection agency standards) and 38 per cent experienced unhealthy air on average.

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The scientists calculated that the observed air pollution is calculated to contribute “to 1.6 million deaths [per] year in China [4]” or around 17 per cent of all deaths.

Rohde and Muller have now adapted the method used to gather data for their paper, and used it to create a plug-in for Google Maps to display live pollution data across much of China.

“[The] map provides near real-time information on particulate matter air pollution less than 2.5 microns in diameter (PM2.5),” they wrote.

“Under typical conditions, PM2.5 is the most damaging form of air pollution likely to be present, contributing to heart disease, stroke, lung cancer, respiratory infections, and other diseases.”

The researcher’s map for today shows there are several pockets of northern China marked in green which means ‘good air’. Hong Kong is also clearly identified as having ‘good air’. Large swathes of eastern China have ‘moderate’ air.

Hong Kong has had its share of choking smog, according to the latest air quality index report from the Environmental Protection Department. Pollutants including nitrogen dioxide, ozone and PM2.5 exceeded the government limits in various areas of Hong Kong last year, according to the report.

PM2.5 are microscopic particulate matter smaller than 2.5 microns that can lodge deep inside a person’s lungs and cause health problems in the long term. It hit a high of 119 micrograms per cubic metre, exceeding the 75-micrograms a day limit.

High levels of nitrogen oxide – a compound mostly coming from vehicle exhaust – peaked at 429 micrograms per cubic metre last year in Causeway Bay. This was more than double the limit of no more than 200 micograms per hour set by the government.

Why is diesel now bad news?

8 December 2014

Roger Harrabin

The Mayor of Paris Anne Hidalgo wants to ban diesel cars and the pollution they bring from the streets of the French capital. But not long ago, diesel engines were thought to be environmentally friendly. What could have gone wrong?

Opinion on diesel cars has swung widely over the years.

Diesel is a more efficient fuel than petrol, but in the past diesel engines were often noisy and dirty.

Then, with growing concerns over climate change, car manufacturers were urged to produce cleaner, quieter diesel cars to capitalise on their extra fuel efficiency.

The cars were fitted with a trap to catch the particles of smoke associated with the fuel. Several governments rewarded the manufacturing improvements by incentivising the purchase and use of diesel cars.

But the policy has backfired.

Going into reverse

First, there have been problems with the particle traps – some drivers have removed them because they sometimes don’t work properly unless the car is driven hot.

Second, the diesels are still producing nitrogen dioxide (NO2), which irritates the lungs of people with breathing problems. Diesels make several times more NO2 than petrol cars.

Now, in order to meet European air pollution laws, politicians are being forced into an embarrassing U-turn, telling drivers that they’ve decided they don’t much like diesels after all.

MPs in the UK have mooted a scrappage scheme for diesel cars, while the mayor of Paris has called for a ban.

Several European nations are currently in breach of EU clean air laws.

The EU’s NO2 limit was exceeded at 301 sites in 2012, including seven in London. The concentration on Marylebone Road was more than double the limit.

Districts in Athens, Berlin, Brussels, Madrid, Paris, and Rome are also exceeded the ceiling.


Not just carbon: Key pollutants for human health

  • Particulate matter (PM): Can cause or aggravate cardiovascular and lung diseases, heart attacks and arrhythmias. Can cause cancer. May lead to atherosclerosis, adverse birth outcomes and childhood respiratory disease. The outcome can be premature death.
  • Ozone (O3): Can decrease lung function and aggravate asthma and other lung diseases. Can also lead to premature death.
  • Nitrogen oxides (NO2): Exposure to NO2 is associated with increased deaths from heart and lung disease, and respiratory illness.
  • Polyaromatic hydrocarbons (PAHs), in particular benzo a-pyrene (BaP): Carcinogenic.

Politicians are now scurrying to persuade the courts that they are obeying an EU demand to clean up the air as soon as possible.

The Paris mayor said at the weekend that she wanted the city to become ‘semi-pedestrianised’, with a ban on diesel cars in the city centre and some neighbourhoods given entirely to residents’ cars, delivery vehicles and emergency vehicles.

“I want diesel cars out of Paris by 2020,” she said.

Ms Hidalgo hopes that her plan will improve the quality of the air in a city where, on average, people live six or seven months less than those who are not exposed to the same levels of pollution.

Adding electric vans and putting limits on tourist buses would also help lessen the public health risk, she said.

Premature death

Bikes are expected to become the favoured form of transport, with cycle lanes doubled by 2020 in a $141m (£90m) plan.

The Mayor of London, Boris Johnson has promised to halve pollution, spending around $516m (£330m) to bring 2,400 hybrid buses, zero-emission taxis and 10,000 street trees. The announcement came weeks after he was forced to accept that Oxford Street has some of the highest levels of NO2 in the world.

Central London will also have an ‘Ultra Low Emission Zone’ in 2020. Mr Johnson has previously faced criticism from health and environment lobby groups complaining that he was dragging his feet in meeting EU targets.

The UK government says it is responding to EU demands by bringing forward new plans. Labour say the government has ignored the issue – they demand low-emissions zones in all of the UK’s major cities.

According to the European Environment Agency, air pollution is the top environmental risk factor for premature death in Europe; it increases the incidence of a wide range of diseases.

Particulate matter (PM) and ground-level ozone (O3) are the most harmful pollutants.

Vehicles are by no means the only source of pollutants – some industries are major polluters too, and shipping in some places. But the politicians who run Europe’s biggest cities have protested that they cannot control pollution from industry elsewhere that drifts into their area.

With so many nations failing to meet pollution laws, the EU is under pressure to relax air standards.

670,000 deaths a year the cost of China’s reliance on coa

05 November, 2014

Li Jing

Smog caused by coal consumption killed an estimated 670,000 people in China in 2012, according to a study by researchers that tries to put a price tag on the environmental and social costs of the heavy reliance on the fuel.

Damage to the environment and health added up to 260 yuan (HK$330) for each tonne produced and used in 2012, said Teng Fei , an associate professor at Tsinghua University.

The 260 yuan is made up of two parts: the health cost and the environmental damage caused by mining and transporting coal.

“With existing environmental fees and taxes of between 30 to 50 yuan for each tonne of coal, the country’s current pricing system has largely failed to reflect the true costs,” Teng said.

Tiny particulate pollutants, especially those smaller than 2.5 micrograms (known as PM2.5), were linked to 670,000 premature deaths from four diseases – strokes, lung cancer, coronary heart disease and chronic obstructive pulmonary disease – in China in 2012, Teng said.

That translated to an external cost of 166 yuan for each tonne of coal consumed. Authorities levied only about 5 yuan as a pollution fee per tonne of coal used by consumers including power companies and iron, steel and cement producers.

Mining and transport add 94 yuan per tonne, including through damage to groundwater resources, subsidence, deaths and occupational diseases.

Beijing is considering replacing pollution charges with more stringent environmental protection taxes, but progress on legislation has been slow.

Li Guoxing , from Peking University’s School of Public Health, said the full impact of coal use was still underestimated as the study did not take into account medical costs associated with other pollution-induced diseases such as asthma.

“The health cost [of the study] is only based on the premature death figures due to the limitations of our research data,” said Li. “It could be way higher if we also include medical costs for other chronic illnesses.”

The study found that in 2012, more than 70 per cent of the population was exposed to annual PM2.5 pollution levels higher than 35 micrograms per cubic metre, the country’s benchmark for healthy air quality.

The World Health Organisation sets its PM2.5 safety limit at an annual concentration of 10mcg/cubic metre. That class of particulate was officially recognised as a human carcinogen last year by the International Agency for Research on Cancer, especially its link to lung cancer and a heightened risk of bladder cancer.

In 2012, some 157 million people in China lived in areas where the annual PM2.5 concentration was higher than 100mcg/cubic metre – 10 times the WHO’s recommendation.

A previous study published in British medical journal The Lancet said outdoor air pollution contributed to 1.2 million premature deaths in China in 2010, or 40 per cent of the global total. Former health minister Chen Zhu said this year that pollution caused 350,000 to 500,000 premature deaths a year in China.

The new study – based on research from Tsinghua and Peking universities, the China Academy of Environmental Planning and other government-backed institutes – represents the latest lobbying efforts by some Chinese experts to cap coal consumption.

But this is a difficult task, as the country relies on the fuel for nearly 70 per cent of its energy.

Teng estimates there would be a further cost of 160 yuan per tonne, on top of the 260 yuan calculated in the study, if the long-term social impact of climate change from coal burning were considered.

Zhou Fengqi , a former energy official, said it was impossible for the country to radically slash coal consumption in the coming decades.

Scientists examine the health risks of Hong Kong’s notorious ‘street canyons’

13 October, 2014

Cheung Chi-fai and Ernest Kao

Findings will help urban planners minimise impact of air pollution on residents

Hong Kong’s notorious “street canyons” have become the latest research subject for a group of the world’s top scientists specialising in air pollution and health.

Researchers from Britain, Canada and Hong Kong are conducting a three-dimensional air quality study in the city, which has a unique urban morphology – a dominance of high-rises and a close proximity between the population and traffic.

The study will not only map the three-dimensional movement of air pollutants, but also try to relate the pollution levels to the health of residents living at various heights in high-rises.

It will assist urban planning and building designs to minimise pollution impacts in Hong Kong and other megacities across Asia.

The street canyon effect is often cited as one of the factors in Hong Kong’s worsening air pollution. Closely built high-rises with heavy traffic in between are blamed for blocking ventilation and trapping air pollutants.

Funded by the Health Effects Institute in the US, the 30-month study will be jointly carried out by scientists from King’s College London, University of Hong Kong, the University of British Columbia and Simon Fraser University in British Columbia.

The study consists of two parts. The first, which started in March, collects spatial air pollution data from 100 selected sites across the city. The scope of the pollutants includes fine particles, as well as nitrogen oxides and black carbon.

The second part is to identify suitable canyon sampling sites to measure vertical pollution exposure. Small sensors capable of recording pollutant concentrations as well as weather data will be installed on buildings.

Dr Benjamin Barratt, of the environmental research group at King’s College London, who described Hong Kong as an ideal “urban laboratory”, said they had selected estates in different districts to represent varying characters of street canyons.

He said the first-phase vertical monitoring in Mong Kok, Jordan, Choi Hung and Sai Wan had been completed and participants from two more districts – North Point and Hung Hom – were now being recruited.

He did not want to disclose the estate names, however, as he feared it might mislead the public into thinking that they must be pollution hotspots.

He said two sets of four monitoring units had been mounted on the exteriors of the selected buildings at four height levels. Another two sets are installed inside homes to examine the extent of pollution infiltration.

“We are assessing how pollution emitted from vehicles is trapped inside street canyons, how this changes with height and how much enters the homes of residents,” he said. “Our study is primarily concerned with mapping the level of risk to public health, but these questions are also important for city planners.”

He said the study results would help planners design buildings that minimised the impact of air pollution on the health of residents.

Barratt said they would also launch a study “relating hospital records of specific diseases with patients’ home addresses, including floors”.

Dr Wong Chit-ming, associate professor at HKU’s School of Public Health, who is taking part in the study, said the research was the first and “most systematic” ever done in a city.

Wong said the results could provide more understanding about the dynamics between pollution levels and heights.

“The higher the altitude, the less the air pollution should be. But the situation might be far more complicated than that, as city layouts and wind directions have an impact, too,” he said.

A spokeswoman for the Environmental Protection Department said: ” The dispersion of air pollutants in street canyons is a complex physical phenomenon that the scientific community, including ourselves, has been trying to better understand.

“The research project of King’s College will surely help advance scientists’ understanding of this complex physical phenomenon.”

Clean Air Network chief executive Kwong Sum-yin welcomed the research project as it would provide much-needed urban pollution analysis and modelling on a more micro, rather than a macro, scale.

States: EPA climate regs illegally left out data

Timothy Cama – 08/25/14

The attorneys general from 13 states told the Environmental Protection Agency (EPA) that its proposed rule in June to reduce carbon pollution from power plants broke the law by omitting supporting information.

Led by West Virginia Attorney General Patrick Morrisey, the officials wrote in a Monday letter that the Clean Air Act requires the EPA to include a wide range of data when it proposes certain regulations. That includes the data upon which the rules are based, as well as the methodology and legal interpretations the EPA used.

“These docketing requirements are nondiscretionary,” wrote the attorneys, who represent major coal states including Wyoming, Indiana and Montana. “Finalizing a rule without providing parties with the technical information necessary for meaningful comment renders the final rule unlawful.”

The attorneys go on to say that the climate rule, which was published in two pieces for different kinds of power plants, “repeatedly violated” the data provisions. The agency excluded information from the EPA’s modeling, heat rate data from coal power plants and any technical information to support its rules for modified power plants.

“This is another blatant example of this agency’s disregard for the rule of law,” Morrisey said in a statement. “It is abundantly clear that EPA and the Obama administration will not allow anything to get in the way of enacting these illegal, burdensome regulations on coal-fired power plants.”

The attorneys general asked that the EPA immediately to withdraw the rule and, if the agency wants to go forward it, propose it again with the correct data.

EPA spokeswoman Liz Purchia said she is confident that the rule is on solid legal ground. She cited the numerous recent federal court decisions that have upheld EPA air regulations.

Most of the attorneys in the Monday letter are also participating in a lawsuit filed earlier this month that says the EPA overstepped its authority in writing the climate rule.

Unforeseen Dioxin Formation in Waste Incineration

Ingrid Söderbergh, September 18, 2014

Dioxins forms faster, at lower temperatures and under other conditions than previously thought. This may affect how we in the future construct sampling equipment, flue gas filtering systems for waste incineration and how to treat waste incineration fly ash. These are some of the conclusions Eva Weidemann draws in her doctoral thesis, which she defends at Umeå University on Friday the 26 of September.

Dioxins is a collective name for a specific group of chlorinated organic molecules where some exhibit hormone disrupting and carcinogenic properties. Dioxins can form in waste incineration, as the flue gases cool down.

“When you incinerate waste, some dioxin formation is inevitable, but with the modern flue gas cleaning systems the emission through the stack is minimized, The dioxins are filtered from the flue gases and end up in the fly ash“, says Eva Weidemann.

That dioxins form is known since the 80’s but in the thesis work Eva Weidemann shows that these toxic substances can form under previously unseen conditions. Amongst other findings she describes formation of dioxins within the flue gas filters of a full scale waste incineration plant.

“The intended function of the filters is to remove the dioxins from the flue gas, but I found that they actually formed instead. The dioxin emissions from the plant still falls below the legislative limits, but that the formation takes place in the first place is bad news. We have identified key parameters for the formation and approximate mechanics. My hope is that our findings can contribute to better filter design in the future,” says Eva Weidemann.

Another problem addressed by the thesis is that dioxins can form within the sampling equipment used during high temperature sampling and Eva Weidemann has investigated how to carry out high temperature dioxin sampling to avoid this occurrence. The solution is more efficient cooling at a critical stage, which then prevents the formation of dioxins.

Eva Weidemann have also looked at how dioxins in waste incineration fly ash is influenced by different of hot and cold treatments to find possible methods to detoxify the ashes. The results are not entirely conclusive, but they provide puzzle pieces that can help.

“If we could find a good detoxification method for the fly ashes, it would be an environmental benefit from a dioxin perspective but also in other aspects such as recycling”, says Eva Weidemann.

Waste incineration is despite the dioxins a good option to utilize the energy in waste that cannot be sorted and recycled. The waste is reduced in weight and volume, and bacteria and odor disappears. In addition, combustion a more climate friendly handling method in comparison to landfilling. The methane gas that forms as the waste decays is a worse greenhouse gas than carbon dioxide formed during combustion. The pollution problem attributed to the method in the 80’s and 90’s are today nearly eliminated with the help of advanced filters and purification systems, as well as periodic emission controls.

Guardian: China’s toxic air pollution resembles nuclear winter, say scientists

by Jonathan Kaiman, reporting from Beijing for the Guardian:

Chinese scientists have warned that the country’s toxic air pollution is now so bad that it resembles a nuclear winter, slowing photosynthesis in plants – and potentially wreaking havoc on the country’s food supply.

Beijing and broad swaths of six northern provinces have spent the past week blanketed in a dense pea-soup smog that is not expected to abate until Thursday. Beijing’s concentration of PM 2.5 particles – those small enough to penetrate deep into the lungs and enter the bloodstream – hit 505 micrograms per cubic metre on Tuesday night. The World Health Organisation recommends a safe level of 25.

The worsening air pollution has already exacted a significant economic toll, grounding flights, closing highways and keeping tourists at home. On Monday 11,200 people visited Beijing’s Forbidden City, about a quarter of the site’s average daily draw.

He Dongxian, an associate professor at China Agricultural University‘s College of Water Resources and Civil Engineering, said new research suggested that if the smog persists, Chinese agriculture will suffer conditions “somewhat similar to a nuclear winter”.

She has demonstrated that air pollutants adhere to greenhouse surfaces, cutting the amount of light inside by about 50% and severely impeding photosynthesis, the process by which plants convert light into life-sustaining chemical energy.

She tested the hypothesis by growing one group of chilli and tomato seeds under artificial lab light, and another under a suburban Beijing greenhouse. In the lab, the seeds sprouted in 20 days; in the greenhouse, they took more than two months. “They will be lucky to live at all,” He told the South China Morning Post newspaper.

She warned that if smoggy conditions persist, the country’s agricultural production could be seriously affected. “Now almost every farm is caught in a smog panic,” she said.

A farmer turns soil to plant crops near a state-owned lead smelter in Tianying that has made much of the land uninhabitable. (David Gray/Reuters/Corbis)

Early this month the Shanghai Academy of Social Sciences claimed in a report that Beijing’s pollution made the city almost “uninhabitable for human beings“.