Health Impacts of Air Pollution from Australian Megafires

Models suggest that thousands of Australians experienced dangerous levels of air pollution for several months, leading to more than a hundred deaths.

From October 2019 to February 2020, fire ripped through the Australian bush with unprecedented intensity, killing 34 people and more than 3 billion animals. In a new study, Graham et al. seek to quantify the health impacts of an indirect form of fire damage: the damage caused by poor air quality.

Like car engines, gas stoves, and cigarettes, fires create fine particles with a diameter of less than 2.5 micrometers, called PM2.5. High PM2.5 concentrations can exacerbate a wide range of medical conditions, from lung disease to cardiovascular disease, even leading to death.

By modeling PM2.5 concentrations over southeastern Australia during the period of intense fire activity, the researchers discovered that fire hot spots began to form as early as October and continued to grow over the next 3 months until at least 70% of PM2.5 particles in an area stretching from Melbourne to Brisbane stemmed from the fires.

Around 437,000 people were exposed to air with a PM2.5 concentration of least 25 micrograms per cubic meter of air, which is substantially more than the 15 micrograms per cubic meter of air that the World Health Organization considers an acceptable level for short-term exposure. At times, PM2.5 concentrations increased by more than 3.5-fold because of the fires, the authors estimate.

Using methodology developed by the World Health Organization, the authors estimated that increased PM2.5 levels brought on by the fires led to 171 deaths, or about 30% of the deaths caused by short-term PM2.5 exposure during this time. Sydney and Melbourne bore the brunt of the casualties, with 65 and 23 deaths, respectively, brought forward by bushfire PM2.5, and the rest were scattered throughout the southeastern portion of the country.

This study is the first to simulate PM2.5 levels using an air quality model while taking meteorological conditions and atmospheric processes into account. According to the authors, this method is likely to provide the most accurate regional PM2.5 exposure estimates to date, which is important, as wildfires are expected to increase as climate change leads to hot, dry conditions. Public health officials might draw from studies such as this as they strategize about how to keep populations healthy in the new climate era. (GeoHealth,, 2021)

Health Impacts of Air Pollution from Australian Megafires – Eos
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Air pollution: One in 12 child asthma cases linked to nitrogen dioxide exposure

Researchers estimate that 1.85 million new childhood asthma cases in 2019 were linked with exposure to nitrogen dioxide, a toxic gas released by diesel vehicles

About one in 12 new child asthma cases worldwide are associated with exposure to a toxic gas released by diesel vehicles, according to a new estimate.

Breathing high levels of nitrogen dioxide (NO2) has been previously linked with triggering and exacerbating asthma in childhood. The evidence is now considered strong enough that in 2020, a UK coroner ruled that exposure to the pollutant contributed to the death of 9-year-old Ella Kissi-Debrah.

Susan Anenberg at George Washington University in Washington DC and her colleagues estimate that 1.85 million new childhood asthma cases were linked with the gas in 2019, making up 8.5 per cent of all new cases that year. That is down from 13 per cent four years earlier, mainly due to richer countries cleaning up their air through emissions standards for vehicles and industry.

“I think this is a good news story for NO2. The fraction of new paediatric asthma cases that are attributable to NO2 has dropped,” says Anenberg.

However, the researchers show how unevenly the burden today falls on cities and poorer countries. About two-thirds of the linked asthma cases are in urban areas. And while high-income nations saw NO2-associated cases fall by 41 per cent – driven largely by North America – south Asia and sub-Saharan Africa saw them rise.

The researchers used satellite and land use data to map annual average NO2 levels in one kilometre-wide squares globally, before taking data on total childhood asthma cases to estimate how many were associated with NO2, based on 20 epidemiological studies.

“It is important to note that the actual pollutants in the traffic emission mix that cause asthma remain elusive, and these results do not suggest that we should focus on only emissions of NO2 alone,” says Jonathan Grigg at Queen Mary University of London.

There are some other potential caveats: data on the air pollutant is patchy in some parts of the world, particularly in Africa. And in some low and middle-income countries, the total figures on all child asthma cases may be an underestimate, which would also make the number linked to NO2 too low.

Nonetheless, Anenberg says the results stand and are a reminder that governments around world need to translate tough new guidelines from the World Health Organization into legal standards. “The key takeaway for me is the vast majority of people on the face of the planet are breathing air pollution that is unsafe,” she says.

Air pollution: One in 12 child asthma cases linked to nitrogen dioxide exposure | New Scientist
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The Lancet Planetary Health: 1.8 million excess deaths attributable to urban air pollution in 2019, modelling study suggests

A new modelling study finds that 86% of people living in cities worldwide (or 2. 5 billion people) are exposed to annual average levels of fine particulate matter exceeding the World Health Organisation (WHO) guideline from 2005.

A second study finds that nearly 2 million cases of asthma in children are linked to traffic-related nitrogen dioxide air pollution, with two in three occurring in cities.

Together, the studies highlight the urgent need to improve air quality in cities and reduce exposure to pollution, particularly among children and the elderly. 

Approximately 86% of people living in urban areas across the globe, or 2.5 billion people, are exposed to unhealthy particulate matter levels, leading to 1.8 million excess deaths in cities globally in 2019.

Additionally, nearly 2 million asthma cases among children worldwide were attributable to NO2 pollution in 2019, with two in three occurring in urban areas.

Both studies are published in The Lancet Planetary Health journal and highlight the ongoing need for strategies to improve air pollution and reduce exposure to harmful emissions, particularly among children and the elderly.

1.8 million excess deaths attributable to PM2.5 in 2019

In the first study, researchers looked at PM2.5 (fine particulate matter with a diameter of 2.5 micrometres or less) – the leading environmental risk factor for disease. Inhalation is known to increase the risk of premature death from conditions such as cardiovascular disease, respiratory disease, lung cancer, and lower respiratory infection.

Despite over half (55%) of the world’s population living in cities, to date there has been little research into how PM2.5 disease burdens compare across urban areas globally, with most assessments analysing PM2.5 in megacities only. This new study examines PM2.5 concentrations and associated mortality trends in over 13,000 cities globally [1] between 2000-2019.

Average population-weighted PM2.5 concentration across all urban areas globally was 35 micrograms per cubic metre in 2019, with no change from 2000. This is equivalent to seven times the 2021 WHO guideline for annual average PM2.5 (five micrograms per cubic metre) [2]. The authors estimate that 61 in every 100,000 deaths in urban areas was attributable to PM2.5 in 2019.

Although global urban average PM2.5 concentrations were consistent over this period, there were large variations by region. Urban areas in South-East Asia (including India) saw the largest regional increases, with a 27% increase in average population-weighted PM2.5 concentration between 2000-2019. South-East Asian cities also saw the largest increase in PM2.5-attributable mortality rates over this period, increasing by 33% from 63 to 84 in 100,000 people.

Globally, approximately 86% of urban inhabitants (2.5 billion people) lived in areas exceeding the WHO 2005 guideline for annual average PM2.5 exposure (10 micrograms per cubic metre) [1] in 2019 resulting in an excess of 1.8 million deaths.

The research found that decreasing PM2.5 concentrations in urban areas over the two decades (for example, African, European, and North and South American cities experienced 18%, 21%, and 29% decreases in PM2.5 concentrations) did not correspond to the same level of decreases in PM2.5-attributable mortality rates on their own, demonstrating that other demographic factors, for example, an ageing population and poor general health, are influential drivers of pollution-related mortality burdens.

“The majority of the world’s urban population still live in areas with unhealthy levels of PM2.5,” says Veronica Southerland of George Washington University, USA, and lead author of the study. “Avoiding the large public health burden caused by air pollution will require strategies that not only reduce emissions but also improve overall public health to reduce vulnerability.” [3]

The authors acknowledge several limitations with the study. Some uncertainties in the values were unable to be fully accounted for, such as the use of country-wide baseline disease rates in calculations of mortality, which may differ to those specifically in urban areas. This study also only assessed impact of PM2.5 on mortality, without accounting for other health burdens caused by PM2.5 such as low birth weight, premature birth, and cognitive impairment.

Two thirds of paediatric asthma cases linked to air pollution in cities 

In the second study, researchers looked at NO2 (nitrogen dioxide gas), an air pollutant mainly emitted by vehicles, powerplants, industrial manufacturing, and agriculture. Previous research has shown transport-related air pollution, for which NO2 serves as a marker, to be associated with both asthma exacerbation and new onset asthma in children. However, to date there have been no studies specifically looking at trends in the burden of transport-related NO2 pollution on paediatric asthma incidence in urban areas.

In this research, global NO2 concentrations were calculated with a 1km resolution by combining satellite data with datasets on different types of land use, like roads and green space. The NO2 concentrations were applied to population and baseline asthma rates to estimate paediatric asthma incidence attributable to NO2 between 2000-2019 in 13,189 urban areas worldwide.

The study revealed that in 2019 there were 1.85 million new paediatric asthma cases associated with NO2; 8.5% of all new paediatric asthma cases reported that year. Approximately two in three of these paediatric asthma cases attributable to NO2 occurred in the 13,189 urban areas covered in the study. In urban areas, NO2 was responsible for 16% of all new paediatric asthma cases in 2019.

In both 2000 and 2019, 1.2 million paediatric asthma cases in urban areas could be attributed to NO2 pollution, however the rate per 100,000 children decreased by 11% from 176 to 156 per 100,000 children as urban population grew by 14%.

“Our results demonstrate the important influence of combustion-related air pollution on children’s health in cities globally,” says Dr Susan Anenberg of the George Washington University, USA, who is co-first author on the NO2 study and corresponding author of both studies. “In places that have effective air quality management programs, NO2 concentrations have been trending downward for decades, with benefits for children’s respiratory health. Even with these improvements, current NO2 levels contribute substantially to paediatric asthma incidence, highlighting that mitigating air pollution should be a critical element of children’s public health strategies.” [3]

The authors acknowledge some limitations with this study. Baseline paediatric asthma rates may have been underestimated in low- to middle-income countries, leading to an underestimation in NO2 attributable asthma impacts. Similarly, national paediatric asthma rates were used due to a lack of data on urban rates, and asthma prevalence varies within countries. Finally, it is currently unknown whether paediatric asthma incidence is associated with NO2, the traffic-related air pollution mixture, or the broader combustion-related air pollution mixture. The results could be affected by exposure misclassification, which would lead to asthma impacts being underestimated.

The Lancet Planetary Health: 1.8 million exce | EurekAlert!
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Air pollution: US wildfires now lead to air pollution events affecting millions

The simultaneous occurence of extreme levels of ozone and particulate matter have increased significantly in the past decade due to wildfires in the western US

The area of the western US hit by the unusually high co-occurrence of two air pollutants because of wildfires has more than doubled in the past decade, exposing millions more people to dirty air.

California and other western states have seen historic forest fires in the past five years that have claimed lives, destroyed property and forced evacuations. Now there is evidence that the human cost reaches much further than the blazes’ immediate vicinity.

After personally experiencing an increase in smog and smoke in recent years, Daniel Swain at the University of California, Los Angeles, and his colleagues explored the role wildfires play.

Two types of air pollution – tiny particulate matter called PM2.5 and ozone – are both linked to human health concerns, but they tend to peak at different times of the year. If there is a significant level of wildfire activity, however – which in the western US can occur between July and September – it is possible to see simultaneous peaks in the two pollutants. Such a co-occurrence is thought to have a disproportionately more severe health impact than either pollutant in isolation.

Swain and his colleagues looked at an area of the western US stretching from Washington in the north to California in the south, and extending as far east as Montana and New Mexico. They divided the area into 111-kilometre-wide squares. Using data they had previously gathered, supplemented by new satellite data, they looked for what they term extremes in the levels of both PM2.5 and ozone between 2001 and 2020.

Over their 20 year study period, the number of squares experiencing the co-occurrence of the two pollutants more than doubled, from 18.9 per cent to 44.6 per cent. The largest areas affected were seen in hot, dry summers with many fires: 2015, 2017, 2018 and 2020. “It’s a very large increase over a short period of time,” says Swain. 

The number of people affected increased too. On one day – 21 August 2020 – about 46 million people were exposed to peaks in both pollutants.

“It’s a public health crisis, in the sense that likelihood of direct harm to an individual is somewhat low but the cumulative harm to the millions and millions of people who are exposed repeatedly is very high,” says Swain.

The study, along with past research, suggests that an increase in atmospheric ridges of high pressure sitting in place is both driving the start of fires and exacerbating the impact of the resulting air pollution by trapping it.

Swain says the research confirms how widespread the human health impacts are. “Most of the people exposed to these dangerous air pollution episodes are not living in places directly threatened by the flames themselves. People who are ‘safe’ from fires are not safe from the air pollution effects even if they live hundreds of even thousands of miles away,” he says.

Air pollution: US wildfires now lead to air pollution events affecting millions | New Scientist
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Air pollution high in NE Hungary

Air quality has deteriorated in north-east Hungary due to a high concentration of airborne particles, the National Public Health Centre (NNK) said on Monday.

NNK declared air quality to be “dangerous” in Sajószentpéter and Kazincbarcika, while air quality has deteriorated to unhealthy levels in Putnok.

“Concentrations of particles are also considered to be too high in Eger”, Salgótarján, Miskolc and Nyíregyháza, NNK said.

Forecasts show air quality is expected to improve thanks to strong winds on Monday.

Air pollution high in NE Hungary – Daily News Hungary
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Chemical Air Pollution Morphs Into Something Even More Toxic, Study Shows

Remnants of industrial chemicals in the air can potentially transform into new substances more toxic and persistent than the original pollution, according to a global study published on Wednesday.

Using samples gathered around the world, the study published in Nature found that these previously unidentified products are present in the atmospheres of 18 big cities including Lagos, New York, Tokyo, and Warsaw.

Regulatory guidelines like those listed in the Stockholm Convention assess the danger of different chemical pollutants based on how long they remain in the environment, how toxic they are, and to what degree they contaminate living things.

But, the study notes, this approach has been limited to a list of known substances and does not take into account how they may change as they break down.

The research proposes a new framework using laboratory tests and computer simulation to predict what chemicals will arise as products interact with the air and how toxic they will be.

Study main author John Liggio, a research scientist for Environment Canada, worked with a team to test the framework on nine flame-retardant chemicals most commonly found in the atmosphere.

“They are chemicals that are added to a large variety of materials to delay the onset of fire,” Liggio told AFP.

In a laboratory, they observed how these chemicals changed over time when in contact with oxidants in the air and found that they gave rise to 186 different substances.

Comparing these new substances with field samples, they found 19 derived from the five most common flame retardants. None of the 19 had ever been identified in the ambient atmosphere before.

The team then used computer simulations to gauge the persistence, toxicity, and bio-accumulation of the derived chemicals.

They discovered that the new chemicals could have longer-lasting impacts on the environment and could be more toxic than their parent chemicals – in some cases 10 times as much.

“The framework should provide a new avenue for including transformation products in routine air-monitoring programs and for prioritizing transformation products of high concern for further scrutiny,” the study says.

While the study looked at nine common chemical pollutants and their 19 daughter chemicals present in the urban air samples, Liggio says these results are only the tip of the iceberg.

“Likely thousands of different chemicals exist,” he said, adding that future tests will look at vehicle tire chemicals, antioxidants, and other plastic additives.

Another goal is to test toxicity of the pollutants in real-life studies, going beyond the computer modelling used for this study.

Chemical Air Pollution Morphs Into Something Even More Toxic, Study Shows
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Air Pollutants And Meteorological Variables Influence Pollen Concentration: Study

Scientists have found that air pollutants influence pollen concentration and different types of pollens have a unique response to weather conditions.

Pollens remain suspended in the air and form part of the air we breathe. When inhaled by humans, they put a strain on the upper respiratory system. They cause widespread upper respiratory tract and naso-bronchial allergy with manifestations like asthma, seasonal rhinitis, and bronchial irritation.

Airborne pollen varies in character from place to place due to diverse meteorological or environmental conditions. There is growing evidence that airborne pollen plays a crucial role in increasing allergic diseases in the urban environment. As pollen, climatic variables, and air pollutants coexist in nature, they have the potential to interact with one another and exacerbate their adverse effects on human health.

Considering this, Prof. Ravindra Khaiwal from Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, along with Dr. Suman Mor, Chairperson, Department of Environment Studies and Ms. Akshi Goyal, Ph.D. research scholar, studied the influence of meteorology and air pollutants on the airborne pollen of the city Chandigarh. The group explored the relationships of temperature, rainfall, relative humidity, wind speed, direction, and ambient air pollutants mainly, particulate matter and nitrogen oxide to the airborne pollen.

The study has been financially supported by the Department of Science and Technology (DST), Government of India, and is one of the first studies in India trying to understand the impact of air pollutants and meteorological variables on airborne pollen. The study is recently published in Science of the Total Environment, a journal by Elsevier.

The study suggests that each pollen type studied had a unique response to weather conditions and air pollutants. The majority of pollen types were reported in the spring and autumn flowering period. Distinct peaks of airborne pollen were observed during favorable weather conditions, like moderate temperature, low humidity, and low precipitation. It was observed that moderate temperature plays a significant role in flowering, inflorescence, maturation, pollen release, and dispersal. In contrast, pollen grains were eliminated from the atmosphere during precipitation and high relative humidity. A

complex and obscure relationship of airborne pollen was indicated with air pollutants. The scientists plan to examine long-term data sets to establish the trends in the relationship.

Prof. Ravindra Khaiwal highlighted that in terms of the climatic future, it is expected that the urban environment will significantly impact plant biological and phenological parameters.

Therefore, the study’s findings generate useful hypotheses that air pollutants influence pollen concentration and can be further explored as the data set expands in the future.

The current study’s findings could help to improve the understanding of complex interactions between airborne pollen, air pollutants, and climatic variables to aid in formulating suitable mitigation policies and minimizing the burden of pollinosis in the Indo-Gangetic Plain region. This region has been identified as a hotspot of air pollution, specifically during October and November months.

Air Pollutants And Meteorological Variables Influence Pollen Concentration: Study | HealthWire
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Islamabad’s air pollution reaches record highest

Federal capital’s air pollution reaches record highest, reveals the 24 hours ambient air quality report of Pakistan Environmental Protection Agency (Pak-EPA)’s on Wednesday.

According to the report, increased ratio of environmental pollutants causing bad air and degraded atmosphere leading to smog.

The National Environmental Quality Standards (NEQS) by EPA set a threshold of 35 microgrammes per cubic meter for particulate matter of 2.5 microns (PM2.5), 120 microgrammes per cubic meter for sulphur dioxide (SO2) and 80 microgrammes per cubic meter to ensure clean ambiance. The report highlighted that the past 24 hours average of PM2.5 was recorded 198.96 microgrammes per cubic meter which was reported the highest ever during 8 hours average at 280.3 microgrammes per cubic meter from 1600 to 2400 hours.

The other parameters of daily quality report included SO2 and NO2 which are generally released from industrial emissions. The 24 hours average of SO2 was 19.88 microgrammes per cubic meter and 43.44 microgrammes per cubic meter of NO2 and both effluents were recorded within the permissible limits.

When contacted the EPA official informed that the air quality was hazardous due to increased vehicular emissions and prolonged dry weather resulted in huge accumulation of suspended particles of air pollutants in the atmosphere.

The official further informed that the air quality was hazardous for all age groups and the general public was advised to wear face covering outdoors and avoid unnecessary travel in the federal capital due to high pollution level.

To a question, she said that the areas along hilly terrain mostly possessed increased propensity of generating air pollution due to the natural topography creating a blockade for winds causing air pollution.

She further informed that one of the major reasons for Capital’s air pollution was large number of vehicles entering the capital on daily basis. The industrial sector particularly steel manufacturing units spewing dark smoke were the troublemakers and had adopted carbon absorbing scrubbers that helped control dark carbon release into the atmosphere, she added.

During the winter season, many local people in the slum areas and CDA sanitary workers were burning plastic or household waster for heating purposes during cold weather which was also increasing air pollution.

The CDA official clearly mentioned that the Authority’s staff was strictly warned to not burn waste whereas the public was encouraged to report it to concerned director for further action if found any staffer burning waste.

Islamabad’s air pollution reaches record highest – Daily Times
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