Respro® Bulletin Board

Children living in areas with higher air pollution due to PM2.5 particles and very low levels of green space might have up to 62% increased risk of developing ADHD. On the contrary, children living in greener and less polluted areas have a 50% lower risk of developing the disorder. These are the conclusions of a paper published in Environment International with data from 37,000 children from Vancouver (Canada). The study was led by Matilda van den Bosch, researcher at the Barcelona Institute for Global Health (ISGlobal), a centre supported by the ”la Caixa” Foundation.

The aim of this scientific work was to investigate the possible associations between exposure to greenness, air pollution and noise in early life with later incidence of ADHD, one of the most prevalent neurodevelopmental disorders, which affects up to approximately 5-10% children and adolescents. One of the goals of the study was to evaluate possible joints effects of these exposures in relation to ADHD.

The study used administrative data of births in Metro Vancouver from 2000 to 2001 and retrieved data on ADHD cases from hospital records, physician visits and prescriptions. The percentage of green space in the participants’ neighbourhood was estimated with a novel and precise satellite metric, while the residential levels of two air pollutants —NO2 and PM2.5— as well as noise levels were estimated using available exposure models. Finally, the possible associations between the three environmental exposures and ADHD were assessed using a statistical model that allowed to determine hazard ratios.

The researchers were able to identify 1,217 cases of ADHD, equivalent to a 4.2% of the total study population. The green space analysis revealed that participants living in areas with a greater percentage of vegetation had a lower risk of ADHD. More specifically, the results show that a 12% increase in vegetation percentage was associated with a 10% reduction in the risk of ADHD.

Regarding air pollution, the opposite association was observed with PM2.5: participants with a higher exposure to fine particles had higher risk of ADHD (every 2.1 µg increase in the levels of PM2.5 translated into an 11% increase in the risk of ADHD).

No associations were found for the rest of environmental exposures assessed: NO2 and noise.

Joint effects of PM2.5 and vegetation

The results are consistent with previous studies, which found associations between green space and air pollution, respectively, with ADHD. However, most of the research conducted until now focused on the evaluation of single exposures and rarely evaluated joint effects of multiple environmental exposures.

“We observed that children living in greener neighbourhoods with low air pollution had a substantially decreased risk of ADHD. This is an environmental inequality where, in turn, those children living in areas with higher pollution and less greenness face a disproportionally greater risk”, explains lead author Matilda van den Bosch. “These associations are particularly relevant because exposures take place in early life, a crucial period for brain development where children are especially vulnerable. Importantly, these exposures are modifiable, meaning that the findings should be taken into account for healthier urban planning”, she adds.

“Our findings also show that the associations between PM2.5 and ADHD were attenuated by residential green space and vice versa, as if the beneficial effects of vegetation and the harmful effects of PM2.5 neutralized each other”, says Weiran Yuchi, researcher at the University of British Columbia (Canada) and first author of the study.

Children with higher exposure to air pollutio | EurekAlert!

The densely populated Bangladesh capital Dhaka continues to dominate the list of cities with the worst air quality in the world.

On Monday, Dhaka occupied the second position in the list as its air quality index (AQI) was recorded at 179 at 10.57am.

Pakistan’s Lahore and India’s Kolkata occupied the first and third spots, with AQI scores of 190 and 157, respectively.

An AQI between 101 and 200 is considered ‘unhealthy’, particularly for sensitive groups.

Similarly, an AQI between 201 and 300 is said to be ‘poor’, while a reading of 301 to 400 is considered ‘hazardous’, posing serious health risks to residents.

AQI, an index for reporting daily air quality, is used by government agencies to inform people how clean or polluted the air of a certain city is, and what associated health effects might be a concern for them.

In Bangladesh, the AQI is based on five criteria pollutants — Particulate Matter (PM10 and PM2.5), NO2, CO, SO2 and Ozone.

Dhaka has long been grappling with air pollution issues. Its air quality usually turns unhealthy in winter and improves during the monsoon.

A report by the Department of Environment (DoE) and the World Bank in March 2019 pointed out that the three main sources of air pollution in Dhaka ‘are brick kilns, fumes from vehicles and dust from construction sites’.

With the advent of winter, the city’s air quality starts deteriorating sharply due to the massive discharge of pollutant particles from construction work, rundown roads, brick kilns and other sources.

Air pollution consistently ranks among the top risk factors for death and disability worldwide. Breathing polluted air has long been recognised as increasing a person’s chances of developing a heart disease, chronic respiratory diseases, lung infections and cancer, according to several studies.

As per the World Health Organization, air pollution kills an estimated seven million people worldwide every year, largely as a result of increased mortality from stroke, heart disease, chronic obstructive pulmonary disease, lung cancer and acute respiratory infections.

Dhaka’s air quality second worst in the world

Research into samples of 30,000 men in China suggests ability of sperm to swim in right direction could be affected

Air pollution may affect semen quality, specifically sperm motility — the ability of sperm to swim in the right direction — according to a new study analysing the sperm of over 30,000 men in China.

The research, published today in the journal JAMA Networks, also suggests that the smaller the size of the polluting particles in the air, the greater the link with poor semen quality.

“Our findings suggest that smaller particulate matter size fractions may be more potent than larger fractions in inducing poor sperm motility,” wrote the authors of the paper. The researchers believe that these findings highlight yet another reason for the need to reduce exposure to air pollution among men in their reproductive age.

Researchers have long been trying to establish whether there’s a link between air pollution and sperm quality, but it’s been unclear whether the former has adverse health effects on male fertility because the results from studies are often inconsistent among themselves and complicated to put into perspective. There does appear to be reason to believe that pollution may negatively affect fertility in general for the whole of the population, as suggested in this international literature review published in December 2021.

Researchers at the School of Medicine of Tongji University in Shanghai looked at data records from a total of 33,876 men from 340 Chinese cities, aged 34 on average, with a varied degree of exposure to air pollution among them, and whose wives got pregnant through assisted reproduction technology with their sperm between January 2013 and December 2019.

They then looked for patterns between semen quality in relation to whether the participants had been exposed to amounts of particulate matter smaller in diameter than 2.5 micrometres, between 2.5 and 10 micrometres, and 10 micrometres, in various key moments of the 90 days before their visit to the hospital for semen ejaculation. To establish the quality of the semen, the researchers concentrated on factors such as sperm count, concentration, and sperm motility.

Although the researchers couldn’t find a significant link between air pollution and sperm quality in terms of sperm count or concentration — they did find that the more a participant was exposed to smaller particulate matter, the lower both the progressive and the total sperm motility was. Progressive sperm motility is the sperm’s ability to swim forward, while total sperm motility simply refers to the sperm’s ability to swim in general.

Specifically, when exposed to particulate matter smaller in diameter than 2.5 micrometres. there was an estimated decrease in sperm motility of 3.6%, while when exposed to particulate matter of 10 micrometres in diameter, there was 2.44% less sperm motility. Meaning that it’s possible that different size fractions of particulate matter might have differing effects on semen quality, maybe because the smaller the particulate matter, the more likely it is to travel deeper into the human lungs.

The data indicates that the effects of pollution are more prominent when exposure takes place during the initial part of the 90 days of sperm creation — the one called spermatogenesis — rather than the other two phases. This, in turn, may mean that particulate matter affects sperm on a genetic level, according to the researchers, but these are just speculations, and there’s more research to be done in this area.

“The possibility of a link between air pollution and semen quality has been suggested in a number of studies over the years, although not all of them have agreed with this conclusion,” said Allan Pacey, professor of andrology at the University of Sheffield, who was not involved in the research. “This paper adds to the evidence base suggesting the link is real, and is impressive because it uses semen quality data from over 30,000 men.”

“But the level of decline in sperm motility seems to be quite low,” said Pacey, stressing that correlation is not causation. He noted that the paper failed to provide any information about the morphology, shape and size of the sperm, which made it impossible to determine whether pollution might be responsible for deformation of sperm and that’s why their motility is decreased, or whether there were other reasons.

According to Pacey, it is important to take these findings with a pinch of salt. Although the data suggests that pollution may have a negative effect on sperm mobility, there still isn’t enough information to infer whether this can have a significant clinical effect at large, and result in the overall decrease of the ability of men in high pollution areas to become fathers. More research out in the field might help answer that question with more certainty in the future.

Air pollution may affect sperm quality, says study | Air pollution | The Guardian

Revised government data estimates a lower proportion of pollution comes from wood stoves but they remain a ‘major contributor’

Wood burning in homes produces more small particle pollution than all road traffic in the UK, according to revised government data.

The new data significantly cuts the estimated proportion of small particle pollution that comes from wood burners from 38% to 17%. But wood burning pollution remains a “major contributor” to particle pollution, another government report said. Road transport is responsible for 13% of particle pollution.

The data shows tiny particle pollution, called PM2.5, produced by wood burning rose by a third from 2010 to 2020, when it reached 13,900 tonnes a year. This all comes from the 8% of homes that have wood burners, 95% of which have other sources of heating. The data revision was made after a survey of 50,000 homes provided updated information on the use of wood stoves.

Particle pollution is well known to damage health and cause early deaths. “These toxins may enter the bloodstream and be transported around the body, lodging in the heart, brain and other organs,” the report said. “Therefore, exposure can result in serious impacts to health.”

The report also found that since the late 2000s, significant decreases in particle pollution from coal burning, industry and vehicles have been “largely offset by increases in emissions from wood burning in domestic settings and [biomass] burning by industry”.

“Even after this revision, home use of solid fuel is one of the top two sources of particle pollution in the UK, coming from just 8% of UK homes,” said Gary Fuller, at Imperial College London and a member of the Air Quality Expert Group that advises the government.

“My in-box is filled with people who are concerned about the wood smoke that is filling the bedroom of their asthmatic child or ill elderly relative.”

The government data on wood burning pollution is based on laboratory tests of stoves. Fuller said: “We need to remember the lessons from VW and dieselgate, where the air pollution produced in the real world was much greater than those in official tests. Data from New Zealand tells us that the same applies to wood burners, with the way that we light fires and the fuels that we use tending to lead to more air pollution than we expect from official tests.”

“What is staggering is the increase between 2010 and 2020,” said Simon Birkett, of the campaign group Clean Air in London. “There’s still a really big problem. It’s a public health catastrophe, so wood-burning stoves need to be banned urgently. The first step should be to stop the sale or installation of them.”

Other recent research has shown that wood-burning stoves in urban areas are responsible for almost half of people’s exposure to the cancer-causing chemicals found in air pollution particles. Even wood-burning stoves meeting the new “ecodesign” standard still emit 750 times more tiny particles than a modern HGV truck, another study found, while wood burners also triple the level of harmful pollution inside homes and should be sold with a health warning, according to scientists.

The data revision was made after the government conducted a new survey of wood burning in 50,000 homes, the biggest to date. Its estimate of domestic wood consumption was substantially lower than the previous survey.

The government said the reasons for the different results were likely to include previous assumptions that may be wrong, including that most new stoves were not replacements for old stoves and that users did not sometimes mix coal with their wood. Another factor was that the previous estimate included the “Beast from the East” cold period, which the new estimate did not. “However, it is clear that UK residential emissions from domestic combustion will continue to be a major contributor to the UK emissions of particulate matter,” the survey report concluded.

The sector producing the biggest proportion of PM2.5 is manufacturing industries and construction, which is responsible for 27%. But Fuller said: “Lots of people live closer to home chimneys than they do to industrial sources and major motorways. This leads to greater exposure to wood burning pollution than we find for many other sources.”

Wood burners emit more particle pollution than traffic, UK data shows | Air pollution | The Guardian