Surkhet air pollution puts residents at risk

Posted on April 8, 2021 by Respro® UK Ltd

On Tuesday, Amrita Sunar from Barahatal Rural Municipality Ward No. 5 took her 21-month-old infant to Madhya Paschim Child Clinic in Birendranagar following complaints of breathing difficulty, itchy eyes and common cold.

“My son has been unwell for the past week so I took him to the clinic. The doctors had to administer supplemental oxygen to him after his health condition worsened,” she said. “The doctors say he is having health issues because of air pollution. They say he is still in danger.”

Sunar said all of her four children have fallen sick due to poor air quality.

“There’s been a wildfire raging in a nearby community forest for the past week. The air has become unbreathable,” she said.

Health professionals in Birendranagar say an increasing number of infants and children have been visiting hospitals across the city with complaints of difficulty in breathing and discomfort to the nose and the eyes.

According to the data of the Karnali Provincial Hospital, 300 children were taken ill due to chest infection and other respiratory diseases in Surkhet district in the last three weeks.

“Surkhet residents have been hugely affected by air pollution. Children are the worst affected,” said Dr Nawaraj KC, a paediatrician in Karnali Provincial Hospital.

According to him, forest fires near human settlements are the main cause of air pollution in Surkhet.

“Immediate measures must be taken to control the wildfires that are contributing to the worsening air quality,” said KC. “If the concerned stakeholders do not take initiatives to control air pollution, it will pose a grave danger to public health.”

Air quality in Surkhet has worsened in the last one month. However, the Department of Environment in Kathmandu has not been able to retrieve the exact data on the extent of the pollution since the equipment used to record the Air Quality Index is out of order.

“The air quality in Surkhet has gone from bad to worse in the past few days. The equipment kept at the provincial police office is defunct so we haven’t been able to determine the exact data,” said Shankar Prasad Paudel, information officer at the Department of Environment.

The District Administration Office in Surkhet recently notified its citizens to avoid outdoors except in emergency situations.

“The District Administration Office has requested children, senior citizens and patients with critical illnesses to adopt necessary precautions while stepping out. These groups are most vulnerable to air pollution and are at risk of experiencing respiratory problems,” the statement signed by Shree Shamsher Ranamagar, information officer at the District Administration Office reads.

According to the data of the District Police Office in Surkhet, wildfires have been reported in 39 community forests of the district in the past few months.

“In the last week itself, 3,345 hectares of forestland have been burning,” said Deputy Superintendent of Police in Surkhet Ram Prasad Ghartimagar.

This month, two individuals died while trying to douse wildfires in Simta Rural Municipality Ward No. 2 and Ward No. 7, according to the data of the District Police Office.

The majority of fire incidents result from human activities such as man made fire in the forests to hunt wild animals or burning of farmland to make way for the planting of new crops.

“Discarded cigarette butts are among the biggest causes of forest fires,” Ghartimagar told the Post. “Most wildfires are a result of human negligence. People should be careful when entering forests during the dry season.” 

Surkhet air pollution puts residents at risk
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First air quality profile of two sub-Saharan African cities finds troubling news: Pollution up to five times over international guidelines

Posted on April 7, 2021 by Respro® UK Ltd

Ambient air pollution is a global public health crisis, causing more than 4.9 million premature deaths per year around the world. In Africa, it has surpassed AIDS as the leading cause of premature death. According to one study, air pollution — specifically, fine particulate matter (PM2.5) — may cause at least as many as 780,000 premature deaths annually in Africa and worsen a significant number of diseases, including asthma, lung cancer, and chronic obstructive pulmonary disease.

Kinshasa, capital of the Democratic Republic of the Congo, and Brazzaville, capital of the Republic of Congo, are both large metropolises. However, neither Kinshasa (population 14. 3 million) nor Brazzaville (population 2.4 million) have had comprehensive air quality monitoring programs. There are no national ambient air quality standards in either country, according to an analysis done by the UN Environment Programme.

A new study, led by Lamont-Doherty Earth Observatory atmospheric scientist Daniel Westervelt and Columbia University undergraduate student Celeste McFarlane, has yielded the first-ever multi-year ambient PM2.5 dataset in Kinshasa and Brazzaville. The team deployed a cadre of low-cost sensors and interpreted data in the context of changing weather and changing human activity related to COVID-19 stay-at-home orders. The study was supported by two local universities and their scientists in both cities, and is published online on Aerosol and Air Quality Research.

What it shows is concerning. During the investigation, which began in March 2018, researchers found PM2.5 is highest during the dry season — June, July, and August — when it is up to five times higher than World Health Organization guidelines. It is lower in the remaining months, thanks in part to rainfall, but even then, it is more than four times higher than WHO guidelines.

“Average PM2.5 concentrations suggest unhealthy levels of human exposure, which, over time, can lead to cardiopulmonary problems and premature death,” said Westervelt.

The study also found that last year’s stay-at-home and lockdown directives in response to COVID-19 corresponded to a 40% decrease in PM2.5. “

We were able to demonstrate that it is possible to robustly characterize air quality in African megacities using well-calibrated, relatively simple, cheap devices,” Westervelt said.

He added that given the health risks from air pollution, this data is urgently needed to draw attention to the problem. Researchers hope this study will lead to more concerted efforts to characterize sources of air pollution and develop strategies to mitigate the negative health impacts. Study collaborators include: Columbia University, Department of Chemical Engineering; Ecole Régionale postuniversitaire d’Aménagement et de Gestion Intégrés des Forêts et Territoire tropicaux (ERAIFT) Kinshasa Democratic Republic of Congo; World Bank Group; Kinshasa, Democratic Republic of Congo; Département de chimie, Université Marien Ngouabi, Brazzaville, Republic of Congo; Washington State Department of Ecology; Department of Chemistry, University of California Berkeley; 9OSU-EFLUVE — Observatoire Sciences de l’Univers-Enveloppes Fluides de la Ville à l’Exobiologie, Université Paris-Est-Créteil, France; NASA Postdoctoral Program Fellow; Goddard Space Flight Center; Center for Atmospheric Particle Studies, Carnegie Mellon University; Kigali Collaborative Research Centre, Kigali, Rwanda; and NASA Goddard Institute for Space Studies.

Story Source:

Materials provided by Earth Institute at Columbia University. Original written by Marie DeNoia Aronsohn. Note: Content may be edited for style and length.

First air quality profile of two sub-Saharan African cities finds troubling news: Pollution up to five times over international guidelines — ScienceDaily
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COVID-19 pandemic highlights the urgent global need to control air pollution

Posted on April 6, 2021 by Respro® UK Ltd

A new commentary published online in the Annals of the American Thoracic Society provides an exhaustive examination of published research that discusses whether air pollution may be linked to worse COVID-19 outcomes. The studies that the authors examined look at several potential disease mechanisms, and also at the relationship between pollution, respiratory viruses and health disparities.

In “COVID-19 Pandemic: A Wake-Up Call for Clean Air,” Stephen Andrew Mein, MD, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, and colleagues discuss several ways that the COVID-19 pandemic highlights the urgent need to address the global problem of air pollution through sustainable local and national policies to improve respiratory health and equity worldwide. More than 91 percent of the world’s population lives in areas that exceed the World Health Organization’s air quality guidelines and more people are impacted by worsening air quality each year.

The commentary focuses on the health effects of ambient air pollution. Ambient air pollution consists of potentially harmful pollutants, such as small particles and toxic gases, emitted by industries, households, cars and trucks. International studies have shown that exposure to these pollutants worsens viral respiratory infections and new studies are showing a similar association with ambient pollution and COVID-19 outcomes.

“There are a multitude of studies showing that exposure to higher long-term ambient air pollution is associated with both increased risk of infection and death from COVID-19,” Dr. Mein said. “Historically, air pollution has been linked with worse outcomes, including higher mortality, due to other respiratory viruses like influenza.”

He added, “Research that we examined on pollution during the COVID-19 pandemic has found similar detrimental effects. New research on COVID-19 adds further evidence of the adverse effects of ambient air pollution and the urgent need to address the public health crisis of pollution.”

One of the most prominent studies that the authors examined, in which COVID-19 mortality was modeled, found that each small (1 ?g/m3) increase in long-term fine inhalable particle (PM2.5) exposure was associated with an 8 percent increase in mortality during the pandemic. Another study concluded that air pollution has contributed 15 percent to COVID-19 mortality worldwide.

“The studies we reviewed evaluated whether long-term, ambient air pollution exposure that occurred years prior to the pandemic was associated with worse COVID-19 outcomes,” Dr. Mein stated.

The exact mechanisms for the association between long-term pollution and poor COVID-19 outcomes are not fully known. However, scientists have suggested several theories. Long-term exposure to air pollution may impair the immune system, leading to both increased susceptibility to viruses and more severe viral infections.

Higher air pollution exposure is associated with higher rates of heart disease and metabolic disorders such as diabetes, which are known to be risk factors for severe disease and death from COVID-19. These chronic effects would have occurred prior to the reported reductions in air pollution since the start of the COVID-19 pandemic.

A major point of the authors’ commentary is that improved air quality (due to less travel and industrial activity) during the pandemic may have reduced morbidity and mortality from non-communicable diseases. “Research evaluating associations between the dramatic reduction in ambient air pollution during the global lockdowns and health care utilization for respiratory conditions would further confirm the impact of ambient air pollution on non-communicable diseases and the need to reduce air pollution to improve overall health.”

The authors also noted that much of the research about ambient air pollution and the COVID-19 pandemic is just emerging. “While the primary association between air pollution and COVID-19 outcomes has been generally consistent, there is still much research to be done. In particular, there is a need for studies that adjust for individual-level risk factors, since current studies have been restricted to county or municipal-level exposure and outcome data. Research also needs to be conducted to evaluate whether air pollution is contributing to the stark differences in COVID-19 outcomes among minority groups.”

Racially and ethnically diverse communities are more likely to be located in areas closer to industrial pollution such as PM2.5 and nitrogen dioxide, and to work in types of businesses that expose them to more air pollution. These inequalities in residential and occupational air pollution exposure may be one of the causes of the stark disparities of the COVID-19 pandemic along racial and ethnic lines.

In conclusion, the authors state, “The COVID-19 pandemic has highlighted the widespread health consequences of ambient air pollution, including acute effects on respiratory immune defenses and chronic effects that lead to higher risk of chronic cardiopulmonary disease and acute respiratory distress syndrome (ARDS). These chronic health effects likely explain the higher COVID-19 mortality among those exposed to more air pollution. The pandemic has also provided a glimpse into the health benefits of cleaner air. As we emerge from this devastating public health crisis, COVID-19 is a wakeup call for the need to adopt stricter air quality standards and end our tolerance for pollution in disadvantaged neighborhoods. As part of our post-COVID-19 recovery, we must clean up the air to improve respiratory health and equality worldwide.”

COVID-19 pandemic highlights the urgent global need to control air pollution | EurekAlert! Science News
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Air pollution: Research links black carbon to increased cancer risk

Posted on April 1, 2021 by Respro® UK Ltd

Long-term exposure to black carbon, a constituent of fine particle air pollution, could increase lung cancer risk by 30%, according to researchers in France.

Could stepping out for a breath of fresh air come with its own health risks? Research from France’s national institute of health and medical research, Inserm, published Wednesday, March 24 , singles out black carbon as a constituent of air pollution that could increase cancer risk, especially for lung cancer. Black carbon is produced by incomplete combustion, particularly related to vehicle traffic. Although, in 2013, the International Agency for Research on Cancer (IARC) categorized all fine particles as known human carcinogens, they may not all have exactly the same health impacts.

Black carbon could increase lung cancer risk

Since 1989, Inserm has been annually following up the health of some 20,000 volunteers (the Gazel cohort). This includes data on where participants have lived, as well as their habits, allowing for a better understanding of the researchers’ findings. “Those with the highest levels of exposure to black carbon since 1989 presented an approximately 20% increased cancer risk compared to those with the lowest exposures. An increased risk that rose to 30% for lung cancer,” reveal study authors Emeline Lequy and Bénédicte Jacquemin.

In light of the situation, the researchers consider that: “At an individual level, it is difficult to recommend measures for limiting exposure to black carbon from ambient air particles. However, it is possible to adjust public policies if we can show which air pollutants cause the most harm. So we hope that our findings will help to expand knowledge in order to guide and refine these policies, for example by taking specific measures against black carbon, which mainly comes from automobile traffic.”

While continuing to research the health impact of black carbon, the researchers also aim to study the health impacts of other specific pollutants, notably metals.

Air pollution: Research links black carbon to increased cancer risk
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Urban and transport planning linked to 2,000 premature deaths per year in Barcelona and Madrid

Posted on March 31, 2021 by Respro® UK Ltd

Failure to comply with international exposure recommendations for air pollution, noise, heat and access to green space is associated with more than 1,000 deaths per year in Barcelona and more than 900 in Madrid, accounting for 7% and 3% of overall premature mortality, respectively.

This is the conclusion of a new study by the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation. This study is the first to estimate premature mortality impacts and the distribution by socioeconomic status of multiple environmental exposures related to urban planning and transport in the two cities.

Today, more than half of the global population lives in cities. In Spain, this trend is even more pronounced, with 80% of the population living in urban areas. Madrid and Barcelona are two of Europe’s most populous cities, and they also have some of the highest rates of socioeconomic inequality among inhabitants. Recent studies in European cities such as Vienna, Bradford and Barcelona have shown that a considerable proportion of the premature mortality burden—between 8% and 20%—is associated with poor urban and transport planning.

The new study, published in Environmental Research, estimated the impact of non-compliance with international exposure level recommendations for air pollution—fine particulate matter (PM2.5) and nitrogen dioxide (NO2)—as well as excess heat, traffic noise and lack of green space on residents over 20 years of age in Barcelona and Madrid, cities with different urban planning practices. Whereas Madrid is structured around a central nucleus where most economic activity is concentrated, Barcelona is a compact city whose economic activity is distributed across different neighborhoods.

The study focused on identifying environmental inequities. “Our goal was to identify the population groups that were most exposed and most vulnerable to the effects of poor urban and transport planning,” commented ISGlobal researcher Tamara Iungman, lead author of the study. As for methodology, the researchers used a tool called Urban and Transport Planning Health Impact Assessment (UTOPHIA), which was developed by a team at ISGlobal. “We compared current exposure levels with international recommendations and estimated the fraction of preventable premature deaths that could be avoided if we were to comply with those recommendations,” explained Iungman.

Attributable Deaths

The findings showed that non-compliance with WHO’s exposure recommendations for air pollution, noise, and access to green space, along with excess heat, were associated with 1,037 premature deaths per year in Barcelona. Fine particulate air pollution was the exposure associated with the highest premature mortality, accounting for 524 deaths per year (48% of total attributable deaths), followed by lack of green space (277 deaths), exposure to traffic noise (124 deaths), heat (112 deaths) and exposure to NO2 (12 deaths).

For Madrid, the total number of deaths attributable to non-compliance with international recommendations was 902. Lack of green space was the exposure associated with the highest premature mortality (337 deaths per year), followed by excessive heat (244 deaths), NO2 air pollution (207 deaths), PM2.5 air pollution (173 deaths) and noise (148 deaths).

An earlier ISGlobal study attributed 20% of premature mortality in Barcelona to poor urban and transport planning. “The lower values obtained in this health impact assessment of Barcelona and Madrid—7.1% and 3.4%, respectively—could be attributed to the fact that physical activity was not included in this study, in addition to improvements in adverse exposure levels in recent years, as well as the different methodology used to estimate the mortality attributable to noise,” commented Iungman.

Differences Between Barcelona and Madrid

With better urban and transport planning, Barcelona could avoid nearly twice as many deaths as Madrid: 72 versus 33 deaths per 100,000 inhabitants. “This difference can be partly explained by the fact that the scientific evidence associates higher mortality with exposure to PM2.5, which is higher in Barcelona; another explanation would be the greater traffic and population density in Barcelona than in Madrid, given that its area represents 1/6th of Madrid’s”, explained ISGlobal researcher Natalie Mueller, coordinator of the study.

With an annual average of 15 μg/m3, Barcelona exceeded the maximum level recommended by the World Health Organisation (WHO) for PM2.5 (10 μg/m3). For NO2 levels, however, the city’s annual average of 37 μg/m3 was under the recommended maximum of 40 μg/m3. Madrid exceeded the WHO recommendations on both counts, with an annual average of 11 μg/m3 for PM2.5 and 42 μg/m3 for NO2.

The main difference between the two cities was in air pollutants. The findings showed higher levels of fine particulate matter in Barcelona and NO2 in Madrid, as well as different spatial distributions: high levels of PM2.5 throughout Barcelona and higher levels of NO2 in the center of the Spanish capital. “While the main source of NO2 emissions is local motor-vehicle traffic, fine particulate matter has a higher dispersion capacity and is also associated with other combustion sources besides traffic,” commented Mueller. “The port and the large industrial areas near Barcelona could influence the high levels of fine particulate matter in the city.”

As for green space, the vast majority of the population in Madrid and Barcelona—84% and 95%, respectively—did not have adequate access to these natural environments according to the standards of the WHO, which recommends that people should live within 300 meters of a green space measuring at least half a hectare. This widespread lack of access to green space shows that “in order for green spaces to have health benefits—in addition to mitigating other exposures such as noise and excess heat—it is necessary to consider not only their availability in the city, but also their distribution so that residents can access them on foot,” commented Mueller.

With regard to noise, 97% of the population of Madrid and 96% of the population of Barcelona were exposed to traffic noise levels higher than the WHO’s recommended values. “Both cities had a considerable mortality burden attributable to traffic noise, which underscores how important it is to reduce noise to improve the health of the population,” argued Mueller.

Although there are no specific guidelines for heat, the researchers calculated the temperature corresponding to the smallest number of heat-related deaths in each city: 22.5°C for Barcelona and 21.5°C for Madrid and estimated the impacts of a potential reduction of 1º. “The two cities had similar attributable mortality rates and we found correlations between less green space and higher levels of heat and noise,” added Iungman.

Environmental Inequities

The findings show that poor urban and transport planning in Barcelona is associated with higher mortality in census tracts with lower socioeconomic status, whereas in Madrid the attributable mortality burden varied by environmental exposure. Although air pollution, lack of green space and excessive heat are widespread problems in Barcelona, attributable mortality rates were overall higher in the most deprived areas. Thus, populations in the most deprived census tracts had a mortality risk 1.26 times higher than that of the least deprived groups, probably because of an already higher underlying vulnerability.

In Madrid, the most deprived neighborhoods had higher exposure to PM2.5 and heat than the least deprived neighborhoods, while the inverse was true for NO2 and noise. This is probably due to the fact that lower socioeconomic population subgroups reside more peripheral and closer to industrial areas, where the cost of living is cheaper -and thus they are more exposed to PM2.5 and heat-, while middle and upper middle socioeconomic population reside in Madrid highly trafficked city center, with greater exposure to NO2 and traffic noise. With respect to green spaces, lack of access affected people of both low and middle socioeconomic status. This pattern was also reflected in its attributable mortality, where only the least deprived areas were the ones having less adverse impacts, probably due to lower underlying vulnerability and better general health status.

Co-author Mark Nieuwenhuijsen, Director of the Urban Planning, Environment and Health Initiative at ISGlobal, commented: “This analysis is in line with previous research showing that people living in more deprived neighborhoods tend to be more exposed to harmful environmental exposures compared to those living in wealthier areas, although this inequity varies according to the design characteristics and historical development of each city.”

“This study shows that environmental exposures have a large impact on premature mortality and underscores the importance of designing cities with health impacts in mind, valuing the specificities of each urban environment and prioritizing disadvantaged populations,” concluded Nieuwenhuijsen. “Health impact assessments are a powerful tool for guiding policymakers towards cities that are healthy, sustainable and fair for all residents.”

via Urban and transport planning linked to 2,000 premature deaths per year in Barcelona and Madrid

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Pollution forces Nepal schools to close for the first time

Posted on March 30, 2021 by Respro® UK Ltd

Nepal on Monday ordered schools to close as choking smog enveloped the capital Kathmandu, in the first-ever shutdown of the country’s education sector because of pollution.

Kathmandu is currently ranked among the most polluted cities in the world, with the air quality index (AQI) readings well above 300, the highest level of concern, during the weekend.

“It has been decided that educational institutions will be closed until Friday. As far as we are aware, this is the first time schools have been closed because of pollution,” Deepak Sharma, the Ministry of Education spokesman, told AFP.

The government has also urged people to stay indoors and to avoid construction and burning trash.

Experts say that raging wildfires in several parts of the country combined with stagnant atmospheric conditions have caused the thick smog to cover many districts.

“There is not enough movement in the atmosphere right now so pollutants, contributed also by the wildfires, have been trapped to cause the air quality to deteriorate,” said Min Kumar Aryal, a meteorologist at Nepal’s Meteorological Forecasting Division.

On Twitter, Kathmandu residents complained of “stinging eyes” and “itchiness” because of the pollution.

Low visibility caused by the smog has disrupted flights at Kathmandu airport, leaving passengers facing hours-long delays.

The country’s only international airport was temporarily closed on Friday as visibility dropped to 1,000 metres, according to an airport official, before reopening on the same day.

Pollution forces Nepal schools to close for the first time – France 24
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California’s Tougher Diesel Emissions Rules Cut Related Deaths in Half: Study

Posted on March 30, 2021 by Respro® UK Ltd

California’s strict limits on diesel air pollution appear to have paid off.

Since the limits were added in 1990, diesel exhaust-related deaths have been halved, with the largest reductions in deaths seen in lower-income communities, a new study finds.

By 2014, California saw a 78% decrease in diesel emissions, while diesel emissions in the United States fell by only 51%.

The number of annual diesel-related cardiopulmonary deaths in California between 1990 and 2014 was half what would have occurred if the state had the same reduction in diesel emissions as the rest of the country, the researchers estimated.

They added that California’s level of reductions in such deaths could be achieved nationwide if the rest of the country adopted similar restrictions.

“Everybody benefits from cleaner air, but we see time and again that it’s predominantly lower-income communities of color that are living and working in close proximity to sources of air pollution, like freight yards, highways and ports. When you target these sources, it’s the highly exposed communities that stand to benefit most,” said study author Dr. Megan Schwarzman, a physician and environmental health scientist at the University of California, Berkeley’s School of Public Health.

“It’s about time, because these communities have suffered a disproportionate burden of harm,” Schwarzman added in a university news release.

Diesel exhaust contributes significantly to a type of air pollution called fine particulate matter (PM2.5), which can affect children’s lung development, trigger airway inflammation and exacerbate asthma and cardiopulmonary diseases.

The researchers also pointed out that exposure to PM2.5 has been linked to poor outcomes from COVID-19, and that nonwhite communities are disproportionately affected by both.

Diesel exhaust has been designated a human carcinogen by California’s Office of Environmental Health Hazard Assessment (OEHHA).

“There are hundreds of studies around the world that link particulate matter exposure and premature death,” said study co-author Álvaro Alvarado, an air pollution specialist at OEHHA. “In cities with higher levels of air pollution, there are also higher hospitalization rates for respiratory and cardiovascular illnesses and more emergency room visits for asthma.”

The findings were published March 25 in the journal Science.

More information The U.S. National Institute of Environmental Health Sciences has more on air pollution and your health.

SOURCE: University of California, Berkeley, news release, March 25, 2021

California’s Tougher Diesel Emissions Rules Cut Related Deaths in Half: Study | Health News | US News
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Air pollution and physical exercise: when to do more or less

Posted on March 30, 2021 by Respro® UK Ltd

Physical activity is important in preventing heart and blood vessel disease in young people so long as they don’t undertake very strenuous activity on days when air pollution levels are high, according to a nationwide study of nearly 1.5 million people published today (Tuesday) in the European Heart Journal [1].

Until now, little has been known about the trade-offs between the health benefits of physical activity taking place outdoors and the potentially harmful effects of air pollution. Previous research by the authors of the current study had investigated the question in middle-aged people at a single point in time, but this is the first time that it has been investigated in people aged between 20-39 years over a period of several years. In addition, the researchers wanted to see what happens when people increase or decrease their physical activity over time.

The researchers from Seoul National University College of Medicine (South Korea), led by Professor Sang Min Park, looked at information from the National Health Insurance Service (NHIS) in South Korea for 1,469,972 young Koreans living in cities, who underwent two consecutive health examinations during two screening periods: 2009-2010 and 2011-2012. They followed up the participants from January 2013 to December 2018.

At each health check-up the participants completed a questionnaire asking about their physical activity in the past seven days and this information was converted into units of metabolic equivalent task (MET) minutes per week (MET-mins/week). The participants were divided into four groups: 0, 1-499, 500-999 and 1000 or more MET-mins/week. European Society of Cardiology guidelines recommend people should try to do 500-999 MET-mins/week and this can be achieved by, for example, running, cycling or hiking for 15-30 minutes five times a week, or brisk walking, doubles tennis or slow cycling for 30-60 minutes five times a week. [2]

The researchers used data from the National Ambient Air Monitoring System in South Korea to calculate annual average levels of air pollution, in particular the levels of small particulate matter that are less than or equal to 10 or 2.5 microns in diameter, known as PM10 and PM2.5 [3]. The amount of exposure to air pollution was categorised at two levels: low to moderate (less than 49.92 and 26.43 micrograms per cubic metre, μm/m3, for PM10 and PM2.5 respectively), and high (49.92 and 26.46 μm/m3 or more, respectively).

Dr Seong Rae Kim, first author of the paper, said: “We found that in young adults aged 20-39 years old, the risk of cardiovascular diseases, such as stroke and heart attack, increased as the amount of physical activity decreased between the two screening periods in the group with low levels of exposure to air pollution.

“However, in the group with high levels of exposure to air pollution, increasing the amount of physical activity to more than 1000 MET-min/week, which is more than internationally recommended levels for physical activity, could adversely affect cardiovascular health. This is an important result suggesting that, unlike middle-aged people over 40, excessive physical activity may not always be beneficial for cardiovascular health in younger adults when they are exposed to high concentrations of air pollution.”

He continued: “Ultimately, it is imperative that air pollution is improved at the national level in order to maximise the health benefits of exercising in young adults. These are people who tend to engage in physical activity more than other age groups while their physical ability is at its best. If air quality is not improved, this could result in the incidence of cardiovascular diseases actually increasing despite the health benefits gained from exercise.”

The researchers adjusted their results to take account of factors that could affect them, such as age, sex, household income, body mass index, smoking and alcohol consumption. During the follow-up period there were 8,706 cardiovascular events. Among people exposed to high levels of PM2.5 air pollution, those who increased their exercise from 0 to 1,000 MET-min/week or more between the two screening periods had a 33% increased risk of cardiovascular disease during the follow-up period compared to those who were physically inactive and did not increase their exercise, although this result was slightly weaker than that needed to achieve statistical significance. This means an extra 108 people per 10,000 might develop cardiovascular disease during the follow-up period.

Among people exposed to low to moderate levels of PM2.5, those who increased their physical activity from none to 1,000 MET-min/week or more had a 27% reduced risk of developing cardiovascular disease compared to those who remained inactive, although this result was also not quite statistically significant. This means 49 fewer people per 10,000 might develop cardiovascular disease during the follow-up period.

Dr Kim said: “These results are very close to statistical significance. In fact, a further analysis presented in Figures 2 and 3 of our paper shows that statistical significance was achieved for increasing and decreasing amounts of physical activity.” For low to moderate levels of PM10 air pollution, there was a statistically significant 38% or 22% increased risk of cardiovascular disease among people who started off doing 1,000 MET-min/week or more and then reduced their activity to none or to 1-499 MET min/week, respectively, compared to people who maintained the same high level of activity. These results were statistically significant and mean that 74 and 66 extra people per 10,000 respectively would develop cardiovascular problems during the follow-up period.

Professor Sang Min Park, who led the research, said: “Overall, our results show that physical activity, particularly at the level recommended by European Society of Cardiology guidelines, is associated with a lower risk of developing heart and blood vessel disease among young adults. However, when air pollution levels are high, exercising beyond the recommended amount may offset or even reverse the beneficial effects.”

The study cannot show that air pollution causes the increased cardiovascular risk, only that it is associated with it. Other limitations are that there was no information on whether or not the exercise took place indoors or outdoors; participants may not have remembered correctly the amount of exercise they took in the seven days before they attended their screening interview, although this is unlikely; PM2.5 data were only measured in three major cities; and the researchers did not investigate the short-term effects of exposure to air pollution.  

Air pollution and physical exercise: when to do more or less
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