Pollutant emitted by forest fire causes DNA damage and lung cell death

Posted on October 27, 2017 by Respro® UK Ltd

When exposed in a laboratory to pollution levels comparable to those found in the atmosphere of the Amazon region during the forest and crop burning season, human lung cells suffer severe DNA damage and stop dividing. After 72 hours of exposure, over 30 percent of the cultured cells are dead. The main culprit appears to be retene, a chemical compound that belongs to the class of polycyclic aromatic hydrocarbons (PAHs). These results have been reported by a group of Brazilian researchers in the journal Scientific Reports.

“We found no information on the toxicity of retene in the scientific literature. I hope our findings serve as an incentive for further study and for environmental concentrations of retene to be regulated by health organizations,” said Nilmara de Oliveira Alves Brito, first author of the article.

“When I was doing my master’s research at UFRN, I noticed that exposure of lung cells to this particulate matter emitted by biomass burning led to mutations in lung cell DNA,” said Alves Brito. “This more recent study set out to investigate the mechanisms by which this happens.”

Methodology

The first step, she explained, consisted of determining the concentration of pollutants to be used in the lab experiments in order to mimic the exposure suffered by people who live in areas of intensely changing land use and plant cover known as the “deforestation arc”—500,000 square kilometers extending westward from eastern and southern Pará into Mato Grosso, Rondônia and Acre.

Using mathematical models, the researchers calculated the human lung’s capacity to inhale particulate matter at the height of the burning season and the percentage of pollutants that is deposited in lung cells. “Based on this theoretical mass, we determined the concentration levels to be tested using cultured cells,” Alves Brito said.

The pollutants used in vitro were collected in a natural area near Porto Velho, Rondônia during the burning season, which peaks in September and October.

“The samples were collected using a device that draws in air and deposits fine particles with a diameter of less than 10 micrometers in a filter. We were interested in studying these very fine particles because they’re small enough to penetrate the alveoli in the lungs,” Alves Brito said.

According to Professor Paulo Artaxo of the University of São Paulo, the filters were frozen shortly after the particulate matter was collected because the organic compounds found in the pollution plume are highly volatile. “This material was shipped to São Paulo and diluted in a nutritive solution, which was then applied to the cell cultures,” he said. “The proportion of pollutants used was the same as that found in the air inhaled by the inhabitants of Porto Velho.”

The cultured cells treated with the solution were compared with a group of control cells, which received only the solvent used to extract pollutants from the filters. The aim was to confirm that any adverse effects observed were caused by the particulate matter and not by the solvent.

Immediate effect

In the very first moments of exposure, the lung cells began producing large amounts of pro-inflammatory molecules. Inflammation was followed by an increase in the release of reactive oxygen species (ROS), substances that cause oxidative stress. Large amounts of ROS cause damage to cellular structures.

“To understand the pathways that were inducing oxidative stress, we analyzed the cell cycle and found that it was impaired by an increase in the expression of proteins such as P53 and P21. The cells stopped replicating, which suggested that DNA damage was occurring,” Alves Brito said.

The researchers performed specific tests to confirm genetic damage. Based on their observation of increased expression of the protein LC3 and other specific markers, they also found that the cells entered a process of autophagy whereby they degraded their own internal structures.

“All this damage was observed in only 24 hours of exposure,” Alves Brito said. “As time passed, the genetic damage increased, and the cells entered a process of apoptosis and necrosis.” Whereas only 2 percent of control cells had died from necrosis after 72 hours, in the culture treated with pollutants, cell mortality reached 33 percent.

“Not all the cells die, but the survivors suffer DNA damage, which may predispose them to the development of cancer in future,” Alves Brito said.

Before beginning the experiment with cultured cells, Alves Brito and collaborators completed an analysis of the substances present in the particulate matter collected in the Amazon region. They identified the presence of several PAHs, many of which are known to be carcinogenic. The results of this analysis were published in 2015 in the journal Atmospheric Environment.

“We observed that the most abundant PAH was retene,” Alves Brito said. “We therefore decided to repeat the experiment with the cells using this substance in isolation but at the same concentration as that found in the particulate matter. We observed that retene alone also induced DNA damage and cell death.”

According to Artaxo, the death of large numbers of lung cells in a living organism can lead to breathing problems and even severe diseases such as pulmonary emphysema.

“In a previous study, we showed that the decline in deforestation from 27,000 km2 in 2004 to 4,000 km2 in 2012 avoided the death of at least 1,700 people from diseases associated with pollution,” he said. “Curiously enough, most of these deaths wouldn’t have occurred in the Amazon but in the South of Brazil because of the long-distance transportation of pollutants and also because of the region’s higher population density.”

Global relevance

Although retene is not emitted by the burning of fossil fuels, the main source of pollution in Brazil’s urban areas, the researchers say that this compound can be found in the atmosphere in São Paulo and other cities, probably owing to the burning of sugarcane and other kinds of biomass on nearby farms.

In the article, the researchers note that while most research on exposure to air pollution focuses on the role of fossil fuels in atmospheric pollution, some 3 billion people worldwide are exposed to air pollution from biomass burning, including the use of wood or coal as fuel in cooking stoves or home heating, as well as from deforestation and agricultural practices. Moreover, the authors add, some 7 million deaths worldwide, or one in every eight deaths, result from exposure to air pollution, according to a report issued by the World Health Organization (WHO) in 2012.

“The combination of forest fires and human occupation has turned biomass burning into a serious threat to public health. The majority of forest fires occur in the deforestation arc, directly impacting over 10 million people in the area. Many studies have identified severe effects on human health, such as increased incidence of asthma, morbidity and mortality, mainly in the most vulnerable populations such as children and the elderly,” the authors note.

Source: Pollutant emitted by forest fire causes DNA damage and lung cell death

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Sulfur dioxide pollution tied to degraded sperm quality

Posted on October 26, 2017 by Respro® UK Ltd

Men’s sperm counts have plummeted by up to 60% over the last 40 years in Western countries and by nearly 30% since 2001 in China. Experts lack firm answers regarding the cause of the sperm deficit but suspect that behaviors such as smoking or exposures to hormone-disrupting compounds in plastics or pesticides are to blame. A handful of papers have questioned whether air pollution could also affect semen quality. Now, a new study links sulfur dioxide emitted from burning fossil fuels to depressed sperm count and concentration in Chinese men (Environ. Sci. Technol. 2017, DOI: 10.1021/acs.est.7b03289).

“Infertility is a global public health issue affecting at least 50 million couples worldwide,” says Yuewei Liu, an environmental epidemiologist at Hubei Provincial Center for Disease Control & Prevention. Data suggest that poor semen quality accounts for 90% of male infertility. Impaired semen clearly interferes with conception, but it is also often an indicator of other health problems.

While most research has focused on risky behaviors and commercial chemicals as potential causes, experts have recently suggested that air pollutants might damage sperm quality. However, studies on air pollution and semen quality have been inconsistent due to inaccurate measures of an individual’s exposure to pollutants and insufficient sample sizes.

So Liu and his team decided to study semen samples collected from 1,759 men in Wuhan, China. They had all visited Tongji Hospital from 2013 to 2015 seeking help to conceive a child with their partners. The researchers measured sperm concentration, total sperm, and total motile sperm in each sample, controlling for factors that might affect semen quality such as age and smoking. Then the scientists drew on government data from nine air quality monitoring stations in Wuhan—a transportation hub and manufacturing powerhouse—to estimate exposure to air pollutants such as sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone. Liu employed a model that analyzed the location of the monitoring stations in relationship to each man’s home to predict individual daily pollutant exposures. Because human sperm develops over 90 days, the researchers calculated pollution exposures for the 90 days prior to semen collection so they could look at key periods of sperm development.

When Liu and the team used a statistical test to rate semen quality against increasing air pollution, they found no impact from NO2, CO or O3. However, for each 10 µg/m3 increase in SO2 exposure during the first stage of sperm development, sperm concentration dropped by 6.5%, total sperm count by 11.3%, and total motile sperm by 13.2%, Liu says. Levels of SO2 during the later stages of sperm development did not appear to impact sperm quality. The annual mean SO2 concentrations in Wuhan during the study period ranged from a high of 33 µg/m3 in 2013 to 18 µg/m3 in 2015. In the U.S., annual mean SO2 concentration was less than 5 µg/m3 in 2013.

“Our results indicate for the first time that SO2 exposure may lower semen quality by affecting the earliest stage of sperm development, 70 to 90 days before ejaculation,” Liu says. He speculates that SO2 could impair sperm by triggering oxidative stress and damage to DNA. “Given the limited evidence from epidemiological and in vivo studies, further studies are needed to confirm the association of NO2, CO and O3 with semen quality,” Liu adds. He recommends caution in generalizing the findings to other populations since the men were all from one city in China.

“Even though the study was limited to one city, this paper adds evidence to the existing literature showing a downward trend in sperm concentration and count with increasing exposure to air pollution,” says Bénédicte Jacquemin, an epidemiologist at the health research institute ISGlobal in Barcelona. The study’s findings are more applicable to countries such as China and India where SO2 pollution is severe, she notes. “Exposure to SO2 might not be the cause of decline in sperm quality in North America and Europe, as regulations have lowered SO2 levels for a couple of decades now.”

Source: Sulfur dioxide pollution tied to degraded sperm quality | Chemical & Engineering News

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Flouting the law aggravating air pollution, killing thousands 

Posted on October 25, 2017 by Respro® UK Ltd

The winter is coming and once more days of choking smog are awaiting city dwellers in metropolises of Iran.

A great deal of air pollution in Tehran and other big cities is blamed on a phenomenon called inversion.

Inversions occur during the winter months when normal atmospheric conditions (cool air above, warm air below) become inverted. Inversions trap a dense layer of cold air under a layer of warm air. The warm layer acts much like a lid, trapping pollutants in the cold air near the earth.

Wintertime inversions are a common event in metropolises. Extended inversions can lead to the high levels of fine particles (PM2.5). These high pollutant levels raise significant health and air quality issues, especially on days when the pollutant concentrations exceed the air quality indices.

One of the most important things impacted by an inversion layer is smog. This is the brownish-gray haze that covers many of the world’s largest cities and is a result of dust, auto exhaust, and industrial manufacturing.

Deaths linked with unhealthy environment 

Tehraners as well as many other citizens living in cities of Tabriz, Ahwaz, and Isfahan feel suffocated by the choking smog at the onset of cold seasons.

An estimated 12.6 million people died as a result of living or working in an unhealthy environment in 2012 – nearly 1 in 4 of total global deaths, according to estimates from World Health Organization (WHO) published in March 2016.

In Iran around 33,000 people die each year because they are exposed to unhealthy environment.

As much as 24 percent of global diseases are caused by environmental exposures. Environmental risk factors, such as air, water and soil pollution, chemical exposures, climate change, and ultraviolet radiation, contribute to more than 100 diseases and injuries.

In terms of air pollution according to another report released by WHO, in 2012 around 7 million people died – one in eight of total global deaths – as a result of air pollution exposure. As per another report, more than 5.5 million people worldwide are dying prematurely every year as a result of air pollution making it the fourth-leading cause of death worldwide. The data was compiled as part of the Global Burden of Disease project.

Since 2015, Iran’s Ministry of Health has been calculating the number of deaths linked to air pollution. Based on the figures given by Abbas Shahsavani, a ministry representative who is in charge of air pollution committee, some 12,798 deaths in 25 cities of Iran with a population of 30 million are attributed to air pollution in 2015.

Shahsavani further said that in Tehran alone some 4,810 deaths occurred in 2016 are attributed to air pollution. That was while based on WHO guidelines the PM2.5 must stand at 10 micrograms per cubic meter air annually in Iran it stands at 31.1 micrograms per cubic meter air which is pretty high.

What contributes to air pollution?

Most of the air pollution results from the burning of fossil fuels, such as coal, oil, natural gas, and gasoline to produce electricity and power the vehicles.

After years of suffering highly polluted autumn and winter it is a common knowledge to citizens that vehicles, most significantly clunkers including taxis, buses, and trucks, and also carburetor motorcycles, in addition to power plants, factories, and mines established in close proximity of the cities are the main pollution sources in the country.

It is not lack of knowledge or even inadequate laws that has contributed to such high levels of air pollution.

The clean air bill which turned into a law last October has mandated some 14 responsible organizations and ministries including ministries of oil, interior, culture, industry, intelligence, transport, science, economic affairs, education, justice, presidential directorate executive affairs, central bank, management and planning organization, and Department of Environment to regulate pollutant industries and other factors contributing to air pollution.

What is actually impeding substantial progress in abating air pollution is budget deficiency, lack of professional integrity, mismanagement, and shortsighted and in some cases misguided policies seeking short term benefits or results and on top of that breaking the law to the advantage of a small minority.

Substandard automobile industry 

For one, Iran’s automobile industry is failing to live up to international standards in manufacturing low-emission vehicles. Although the industry ministry and car manufacturers are legally bound to observe the law in producing clean and eco-friendly vehicles in practice they ignore or fail to meet the standards.

As explained by Mehdi Nikdar, head of the transport fleet and fuel management headquarters affiliated with the transport ministry, all car manufacturers are obligated to scrap a car in exchange for each car they produce.

However, despite the fact that some 1.4 million cars are being produced domestically per annum the manufacturers refuse to follow the law and that’s why only 350,000 cars were scrapped last year.

“Some 2 million cars were scrapped over the past 10 years, but the remaining 1.2 million clunkers which will certainly increase every year will also take another 10 year to be scrapped which is too long,” Nikdar regretted.

Only those who import cars are actually scrapping clunkers; car importers are required to scrap 400,000 clunkers for importing 75,000 cars but once the government decides to temporarily reduce or halt car import the number of cars being scrapped will significantly decrease, and that’s where the problem lies, Nikdar added.

Vehicles are recognized as the preliminary culprits of air pollution. There are adequate laws authorizing the responsible organizations to track down pollutant vehicles and either fix them or omit them. But what seems to be real problem is flouting the law by those who are after short-term results regardless of the health threats posed to the public.

Source: Flouting the law aggravating air pollution, killing thousands – Tehran Times

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Madrid reactivates anti-air pollution protocol 

Posted on October 25, 2017 by Respro® UK Ltd

The Madrid City Hall on Tuesday reactivated its anti-air pollution protocol and advised it would step up to level two of the protocol and its subsequent restrictions on traffic after levels of over 180 micrograms of nitrogen dioxide per cubic meter were measured in two monitoring stations in the Spanish capital.

It is the fifth time the protocol has been activated in under a month, coming just a week after it was de-activated.

Although Madrid experienced rainfall for the first time in 50 days on Oct. 17, warm and dry weather returned quickly to Madrid and temperatures around ten degrees centigrade above the average for the time of year and an almost total absence of wind has seen a steady buildup of nitrogen dioxide over the past five days.

The Madrid Town Hall website advises that the first stage of the protocol means that traffic on the M-30 ring road and on access roads into the capital is “limited to 70 kilometers an hour,” both in an out of the city while recommending the use of public transport.

Meanwhile the second stage, which comes into effect on Wednesday, prohibits private vehicles of non-residents from parking in the city center.

A third level would limit the use of private vehicles on certain days of the week, with cars whose licenses end in odd numbers allowed to circulate one day and those with even numbers the next, effectively halving the number of cars on the roads.

With the current weather system expected to remain in place until at least the end of the week and perhaps, longer, it is possible level three could come into use in the coming days.

At the start of October, the Madrid Town Hall confirmed that as of December this year the central Gran Via would be closed to traffic on a permanent basis with only local residents, taxis and public transport able to use the main thoroughfare.

Source: Madrid reactivates anti-air pollution protocol – Xinhua | English.news.cn

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Over 4,800 die from air pollution in Tehran in 2016

Posted on October 24, 2017 by Respro® UK Ltd

A total of 4,810 people died as a result of air pollution in the Iranian Capital of Tehran over a one-year period, according to Health Officials.

Air pollution in Tehran was the most dangerous in the country due to the high number of vehicles in the city, a spokesperson for the Iranian Ministry of Health said, in comments carried by the Tasnim news agency on Monday.

The reported deaths occurred over the course of the most recent year in the Persian calendar, from March 2016 to March 2017.

Particularly in warmer months, the pollution could be so acute that all primary schools, kindergartens in the city and surrounding areas are closed.

Due to a lack of adequate public transport, many Tehran residents have no alternative but to drive a car.

In addition, petrol is both cheap at about 25 cents per litre and of low quality.

Measures were introduced in 2016 that mean drivers of individual cars are only allowed on the road every other day.

Source: Over 4,800 die from air pollution in Tehran in 2016 | The NEWS

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T-Charge: New London traffic charge comes into force 

Posted on October 23, 2017 by Respro® UK Ltd

Drivers of older, more polluting vehicles will have to pay almost twice as much to drive in central London.

Mayor Sadiq Khan’s £10 T-Charge, which mainly applies to diesel and petrol vehicles registered before 2006, has come into force.

It covers the same area as the existing congestion charge zone, bumping up the cost to £21.50 for those affected.

Opponents said the scheme would “disproportionately penalise London’s poorest drivers”.

The measure is the latest attempt by Mr Khan to improve air quality in the capital and according to the mayor’s office, will impact 34,000 motorists a month.

Speaking on the Today programme, Mr Khan said: “We’ve got a health crisis in London caused by the poor quality air.

“Roughly speaking each year more than 9,000 Londoners die prematurely because of the poor quality air – children in our city whose lungs are underdeveloped, with adults who suffer from conditions such as asthma, dementia and strokes directly caused by poor quality air.”

Earlier he said: “I refuse to be a mayor who ignores this and I am determined to take effective action to reduce the harm it does to Londoners.”

However, Simon Birkett, from the campaign group Clean Air London, said the move does not go far enough.

“The Mayor has pledged in his manifesto to restore London’s air quality to legal and safe limits and that means he has to do a whole lot more.

“We want him to take steps which are bigger, stronger an smarter.”

What is changing?

From Monday 23 October, there will be a £10 daily fee for those who drive more polluting vehicles in the congestion charging zone, on top of the existing £11.50 congestion charge.

Vehicles which do not comply with the Euro IV exhaust standard must pay the charge.

The standard defines emissions limits for cars, vans, buses, coaches and lorries. Most vehicles registered before 2006 are likely to exceed these limits.

The zone will operate between 07:00 and 18:00, Monday to Friday.

Line Break

The T-Charge is the first of a series of new rates being introduced in London.

It is due to be replaced by a stricter Ultra-Low Emission Zone in 2020, although Mr Khan is consulting on bringing this forward to 2019.

This will mean diesel cars registered before September 2015 and petrol cars registered before 2006 will face a £12.50 charge.

The mayor hopes to expand the area covered for cars and vans up to the North and South Circular roads in 2021.

City authorities in Birmingham, Leeds, Southampton, Derby and Nottingham have also been advised to impose charges for some polluting diesel vehicles by 2020, the Department for Environment, Food and Rural Affairs (Defra) said.

Paris, Grenoble and Lyon introduced an emission sticker scheme in January which splits vehicles into six different groups depending on their Euro Emissions standard.

Vehicles deemed too polluting – which includes petrol and diesel-powered cars registered before 1997 – are not granted a sticker, banning them from driving in the city during certain times.

Sue Terpilowski, from the Federation of Small Businesses, said: “The introduction of the T-Charge, comes at a time when small and micro-businesses in London are already facing astonishingly high property, employment and logistics costs.

“There is a fear that this will be the final straw that closes businesses and takes jobs.”

Shaun Bailey, conservative environment spokesman at the London Assembly, said: “As an asthmatic I’m well aware of how critical an issue this is for London but we need policies that actually deliver progress.

“By boasting about a policy that so disproportionately penalises London’s poorest drivers and puts jobs at risk, the mayor is simply blowing more smoke into the capital’s already-polluted atmosphere.”

Friends of the Earth air pollution campaigner Jenny Bates said: “Clearly the last thing individuals want is a new charge for moving around, but the grim reality is that nearly 10,000 early deaths are caused in London each year by the capital’s toxic air, so the Mayor is right to try to dissuade drivers bringing the oldest, dirtiest vehicles into central London.

“It’s only one small step towards clean air though – we urgently need a programme of meaningful financial assistance to help drivers of the dirtiest vehicles switch to something cleaner, and bold policies to cut traffic over all.”

Source: T-Charge: New London traffic charge comes into force – BBC News

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Air Pollution in New Delhi Spikes as Millions Burst Firecrackers 

Posted on October 21, 2017 by Respro® UK Ltd

Air pollution levels in India’s capital soared off the charts once again as millions of Indians burst fire crackers to celebrate Diwali, the Hindu festival of lights, despite a Supreme Court ban on the sale of fireworks in the region.

Already one of the world’s most notoriously polluted mega cities, the capital saw its air quality index (AQI) gradually worsen until it reached a level of 1,031 around 9 a.m. on Friday, according to the United States embassy in New Delhi. A reading of 0-50 is considered good, while levels between 300 and 500 are considered “hazardous.” Anything above 500 is considered “Beyond Index.”

By Friday around 1 p.m., the U.S. embassy showed New Delhi’s pollution had nearly halved with AQI at 548, which still appeared to be the worst of any major city in the world.

India’s Supreme Court had banned the sale of firecrackers throughout the national capital region in the days leading up to Diwali, which fell on Oct. 19, after celebrations last year ushered in weeks of poisonous smog. The ban prompted some hand-wringing in the city of more than 20 million people because it targeted a Hindu religious festival.

Although pollution spiked on Diwali last year, firecrackers are not the main cause of air pollution in New Delhi. Air quality generally deteriorates as winter sets in because of a combination of agricultural crop burning in the nearby states of Punjab and Haryana, dust from roads and construction sites, industry, coal power plants and vehicular emissions.

A recent report from the Lancet Commission on Pollution and Health found that air contamination kills roughly 6.5 million people each year and that all forms of pollution cost the global economy an annual $4.6 trillion. The authors said deaths from pollution associated with industrial development are on the rise and that low-income countries, such as India, suffer the worse effects. For poor countries, pollution related deaths and disease cost the equivalent of 1.3 percent of gross domestic product, according to the report.

In India’s vibrant democracy, coordinated action on complex problems such as air pollution is difficult. The issue crosses political jurisdictions, and farmers — who are a key political constituency in India — continue to light fires despite a Delhi High Court directive.

Source: Air Pollution in New Delhi Spikes as Millions Burst Firecrackers – Bloomberg

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Link between forest fire smoke and pollution events discovered 

Posted on October 21, 2017 by Respro® UK Ltd

Smoke from forest fires might contribute to more than half of certain gritty air pollution events in the continental U.S. during the summer, and as much as 20 percent of those events throughout the year, according to new research at The University of Alabama in Huntsville (UAH).

This research could be a step toward developing tools to warn of possible smoke-related pollution events and a better understanding of the potential health effects of smoke from planned and controlled forest burning.

“You could use something like this as a way to determine whether a particular planned burn is going to be a tipping point in going over the pollution limit downwind and whether you should burn that day,” says Aaron Kaulfus, a graduate student in UAH’s Department of Atmospheric Science.

Kaulfus and Dr. Udaysankar Nair, an associate professor of atmospheric science at UAH, used data collected by a pair of instruments on NOAA and NASA satellites to track both hot spots that indicate forest fires and the smoke plumes from those fires. They combined that with data from the Environmental Protection Agency (EPA) on surface sites where air pollution exceeded the safe limit of particles no more than 2.5 microns in size.

Particles smaller than 2.5 microns in diameter (less than one-quarter of the width of a human hair) are small enough to get into a person’s lungs. In heavy-enough concentrations, they can cause damage. EPA estimates biomass burning contributes more than 25 percent of all small particle pollution (identified by the EPA as PM2.5) in the U.S.

The UAH team found that during the summer — when the level of smoke coverage across the U.S. peaks — about 52 percent of all PM2.5 air pollution events in the continental U.S. occur when smoke from forest fires is present.

At rural pollution monitor sites in the Northwestern U.S., more than 80 percent of summer days when smoke is present also have excess PM2.5 particles in the air.

On an annual basis, “at least 20.1 percent of the total daily exceedances coincided with identifiable smoke plumes overhead,” Kaulfus says. “On average, the PM2.5 concentrations were higher for days during which smoke was present over the area.”

While the effects of smoke from forest fires and other biomass burning on levels of ozone (another pollutant) have been studied, Dr. Nair says this is the first attempt to connect smoke and particulate pollution on a nationwide basis.

“We took a national approach to it rather than a station-by-station approach,” Kaulfus says.

This research, which was supported by the National Science Foundation and NASA, has been accepted for publication in the journal Environmental Science and Technology.

While there was smoke overhead in one of five particulate pollution events during the study period, Kaulfus says there isn’t a clear-cut cause-and-effect relationship.

“It was at least plausible that smoke was influencing those surface contaminants,” he says. “But one of the biggest problems with the NOAA smoke product is that there is no way of knowing the vertical profile of where the smoke is, whether it is on the surface or up in the deep layer of the atmosphere.”

“What this really does is give us the upper limit of forest fire smoke’s effects on these pollution events,” adds Dr. Nair.

The area most affected by forest fire smoke was a large wedge in the central U.S., from Canada to east Texas. During the study period, from 2005 to 2016, the NOAA and NASA satellite instruments saw more than 600 days with smoke cover over most of North Dakota, Minnesota, and Iowa, as well as eastern portions of both Kansas and Nebraska, and the eastern half of South Dakota.

While forest fires — both wild and planned — in the continental U.S. contributed smoke over much of the contiguous 48 states, a significant fraction of the smoke recorded over that wedge of most frequent smoke coverage came from forest fires in Canada, Alaska, and even Siberia, Kaulfus says.

“We can see all the smoke being piped down from Canada, all the way down over the eastern cities, extending a couple of hundred kilometers out over the Atlantic and the Gulf Coast,” says Dr. Nair.

Under stable atmospheric conditions, smoke plumes from smoldering fires can be confined to a shallow atmospheric boundary layer near the ground, enhancing small particle pollution at the surface. In the case of high-energy flaming fires, smoke can be injected to higher altitudes.

Routine convection processes can also mix smoke from either kind of fire throughout the deep atmosphere, which can transport smoke thousands of miles from its source and impact downwind air quality.

An area of the western Gulf of Mexico off the coast of Texas and western Louisiana had more than 350 days of smoke cover during the study period, largely caused by forest fires and biomass burning in Mexico and Central America, Nair says.

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Source: Link between forest fire smoke and pollution events discovered — ScienceDaily

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