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Poor air quality could be sending us to hospital for some unexpected reasons

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Short term exposure to poor quality air - like that currently blanketing Sydney -  is associated with several newly identified causes of hospital admissions, say international researchers, who add that the exposure levels can even be below international air quality guidelines. The particulate matter in the air is known as PM2.5, and the researchers suggest that, in the US, for every 0.001 part-per-million of PM2.5 was associated with an 2,050 extra hospital admissions, 12,216 days in hospital, and close to $46 million AUD in care costs for diseases that weren't previously associated with PM2.5 such as sepsis, kidney failure, urinary tract and skin infections. The team suggests that the World Health Organisation air quality guidelines need revising.

Journal/conference: The BMJ

DOI: 10.1136/bmj.l6258

Organisation/s: Harvard T H Chan School of Public Health, Boston, USA

Funder: This study was supported by National Institute of Health (NIH) grants P30 ES000002, R01 ES024332-01A1, R01 ES026217, R01 ES028033, and R21 ES024012; NIH/National Cancer Institute (NCI) grant R35 CA197449; Health Effects Institute (HEI) grant 4953- RFA14-3/16-4; and United States Environmental Protection Agency (US EPA) grants RD-83587201-0 and RD-83479801. The contents of this publication are solely the responsibility of the grantee and do not necessarily represent the official views of the US EPA. Further, the US EPA does not endorse the purchase of any commercial products or services mentioned in the publication. Research described in this article was conducted under contract to the HEI, an organization jointly funded by the US EPA (Assistance Award No CR-83467701) and certain motor vehicle and engine manufacturers. The contents of this article do not necessarily reflect the views of HEI, or its sponsors, nor do they necessarily reflect the views and policies of the US EPA or motor vehicle and engine manufacturers.

Media Release

From: The BMJ

Air pollution linked to several new causes of hospital admissions

Association found even at levels below international air quality guidelines

Short term exposure to fine particulate matter in the air (known as PM2.5) is associated with several newly identified causes of hospital admissions, even at levels below international air quality guidelines, finds a US study published by The BMJ today.

The study also confirms several previously established causes of hospital admission associated with short term exposure to PM2.5 including heart and lung diseases, diabetes, Parkinson’s disease, and diabetes.

As such, the researchers suggest that the World Health Organization (WHO) air quality guidelines need revising.

A research team at the Harvard Chan School of Public Health analysed more than 95 million Medicare hospital insurance claims for adults aged 65 or older in the United States from 2000 to 2012.

Causes of hospital admission were classified into 214 mutually exclusive disease groups and these were linked with estimated daily exposure to PM2.5 based on data from the US Environmental Protection Agency.

The researchers then estimated the increased risk of admission and the corresponding costs associated with a 1 ug/m3  increase in short term exposure to PM2.5 for each disease group.

They found that each 1 ug/m3 increase in PM2.5 was associated with 2,050 extra hospital admissions, 12,216 days in hospital, and $31m (£24m, €28m) in care costs for diseases not previously associated with PM2.5 including sepsis, kidney failure, urinary tract and skin infections.

What’s more, these associations remained even when the analysis was restricted to days when the PM2.5 concentration was below the WHO air quality guideline, suggesting that they need updating, say the researchers.

The researchers point to some study limitations, such as being unable to fully capture costs after discharge, or take account of other factors that could trigger hospital admission, such as smoking, alcohol consumption, and drug use.

However, strengths include the large sample size over a 13-year period and results that remained similar after further analyses, suggesting that they are robust.

As such, they say 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.”

Economic analysis suggests that “even a small increase in short term exposure to PM2.5 is associated with substantial economic effect,” they add.

“Our knowledge of the health effects of PM is still lacking in many areas,” say researchers at the University of Southampton in a linked editorial.

However, they explain that these newly associated diseases represent around a third (31-38%) of the total PM2.5 associated effect, suggesting that current figures for PM2.5 associated illness “might be considerable underestimates.”

They call for more research to uncover new disease associations and explore potential causative mechanisms. “Clearly, there is still much to learn, but we should not mistake knowledge gaps for paucity of evidence,” they write. “The sooner we act, the sooner the world’s population will reap the benefits.”

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