How air pollution causes sepsis, UTIs, kidney failure

*Phenomenon linked to blindness as scientists say particles may hinder blood vessels

Hospital admission go up for a host of life-threatening illnesses – including sepsis, kidney failure and urinary tract infections – never before linked to pollution on days when air quality is poor, a new study reveals. Even low exposure raises the risk of the potentially fatal illnesses, according to the research. It adds to evidence there is no safe amount of tiny particles called PM2.5s that are pumped into the atmosphere by traffic and industry.

The Harvard University researchers found that even short spikes in the harmful particles led to an increase of 5,692 hospitalizations and some $100 million in annual health care costs. They can be inhaled deep into the lungs where they irritate the lining and enter the bloodstream.

The World Health Organisation’s air quality guidelines need revising, say the United States (U.S.) team. An analysis identified several new causes of hospital admissions linked to small increases in particulate matter – such as sepsis and kidney failure. Others included urinary tract and skin infections.

This was on top of established ones like heart and lung conditions, diabetes, Parkinson’s disease and diabetes.“The study shows the health dangers and economic impacts of air pollution are significantly larger than previously understood,” said lead author Yaguang Wei, a doctoral candidate at Harvard TH Chan School of Public Health. It was based on more than 95 million Medicare hospital insurance claims for adults aged 65 or older in the US from 2000 to 2012.

“We wanted to shed further light on the risks of exposure to short-term air pollution by searching for links between such pollution and all diseases that are plausible causes of hospitalisations,” said senior author Dr. Joel Schwartz, who heads Wei’s lab. These were classified into 214 groups and compared with 13 years’ worth of hospital admissions records.

The researchers used data on PM2.5s from the US Environmental Protection Agency (EPA) and matched it with the zip, or postal, codes of participants. Notably, all of the associations remained consistent even on days when daily PM2.5 levels were below the WHO air quality guideline.

Each 1 μg/m3 (one-millionth of a gram per cubic meter of air) rise in short-term exposure was linked with 5,692 more hospitalisations a year, 32,314 days in the hospital and 634 deaths.What is more this included with 2,050 extra admissions and 12,216 days in hospital for diseases not previously connected with PM2.5s – such as sepsis, kidney failure, urinary tract and skin infections.

This remained even when the analysis was restricted to days when the concentration was below the recommended level – suggesting it needs updating.The newly diseases represent around a third of the effect – suggesting current figures for PM2.5 associated illness “might be considerable underestimates.”

“This study discovered several new causes of hospital admissions associated with short term exposure to PM2.5 and confirmed several already known associations, even at daily PM2.5 concentrations below the current WHO guideline,” the researchers wrote. They described the findings published in The BMJ as “robust” owing to the large sample size over a long period of time. Economically, each 1 μg/m3 in PM2.5s corresponded to $100 million (£78m) in annual in-patient and post-acute care costs, and $6.5 billion (£5bn) in the value of lives lost.

“These results raise awareness of the continued importance of assessing the impact of air pollution exposure,” said the study’s principal investigator, Dr. Francesca Dominici, a biostatistician. “The strong evidence of a link between exposure to PM2.5 and many diseases, even at levels below the WHO guideline and, nationally, the National Ambient Air Quality Standards in the US, suggests both sets of guidelines should be reviewed and updated.” Dr. Matthew Loxham, an air pollution toxicologist at the University of Southampton, who was not involved in the study, said knowledge of the health effects of particulate matter “is still lacking in many areas.”

He said: “The harder we look, the more we find. Clearly, there is much still to learn, but we should not mistake knowledge gaps for paucity of evidence. The sooner we act, the sooner the world’s population will reap the benefits.”Loxham and colleagues, writing in an editorial for the journal, call for more research to uncover new disease associations and explore potential causative mechanisms.

World Health Organisation guidelines state the average annual level for PM2.5s should be 10 microgrammes per cubic metre.
Around 91 percent of the world’s population live in places where air quality levels exceed WHO limits.

Air pollution could be contributing to one of the leading forms of blindness in Britain, scientists fear, after discovering the risk of glaucoma rises in smoggy areas.Around half a million people in Britain suffer from glaucoma, which occurs when the optic nerve which connects the eye to the brain becomes damaged, usually by a build up a fluid, which leads to vision loss if not caught early.

It is estimated that in the United Kingdom (U.K.) about one in 50 of people older than 40 have glaucoma, and this rises to almost 10 per cent in people older than 75.Previously, the condition has been linked to high blood pressure and eye injury, but a new study by University College London (UCL) suggests that air pollution may also play a role.

People living in neighbourhoods with higher amounts of fine particulate matter pollution – such as from engines – were at least six per cent more likely to suffer glaucoma than those in the least-polluted areas.Highly polluted areas had particulate matter levels between 10.46 to 19.69 micrograms per cubic metre, while the lowest 8.17 – 9.38.World Health Organisation guidelines say that levels exceeding 10 micrograms per cubic metre pose a health risk and most cities regularly pass that.

The research was published in the journal Investigative Ophthalmology & Visual Science.“We have found yet another reason why air pollution should be addressed as a public health priority, and that avoiding sources of air pollution could be worthwhile for eye health alongside other health concerns,” said the study’s lead author, Professor Paul Foster of UCL’s Institute of Ophthalmology and Moorfields Eye Hospital.

“While we cannot confirm yet that the association is causal, we hope to continue our research to determine whether air pollution does indeed cause glaucoma, and to find out if there are any avoidance strategies that could help people reduce their exposure to air pollution to mitigate the health risks.

“And as we did not include indoor air pollution and workplace exposure in our analysis, the real effect may be even greater.”The findings were based on 111,370 participants of the UK Biobank study cohort, who underwent eye tests from 2006 to 2010 at sites across Britain.

The data was then linked to air pollution measures for their home addresses, from the Small Area Health Statistics Unit, with the researchers focusing on fine particulate matter, equal or less than 2.5 micrometres in diameter, or PM2.5.Although the study is only observational, and it would be unethical to test whether pollution could damage eyes in laboratory conditions, the researchers say there are biological reasons why the particles could damage sight.

“Air pollution may be contributing to glaucoma due to the constriction of blood vessels, which ties into air pollution’s links to an increased risk of heart problems,” said first author Dr. Sharon Chua, of UCL.“Another possibility is that particulates may have a direct toxic effect damaging the nervous system and contributing to inflammation.”Air pollution has been implicated in elevated risk of pulmonary and cardiovascular disease as well as brain conditions such as Alzheimer’s disease, Parkinson’s disease and stroke.