Air pollution impact on health worse than thought: Study

New Delhi : Researchers have recently found that health problems linked to air pollution could be more higher than previously thought.

According to the study, short-term exposure to air pollution has been linked to a staggering number of hospitalisations for numerous health issues like strokes, brain cancer, miscarriage and mental problems.

The research also suggested that the impact could be far wider, despite looking at only one component of air pollution, chiming with a global review published earlier this year that indicated almost every cell in the body may be affected by dirty air, the Guardian reported.

"The drive behind (the new research) was to do the most comprehensive study ever conducted at looking at all possible causes of hospitalisation that could be (linked) to exposure to fine particulate matter," it quoted study co-author Prof Francesca Dominici of Harvard University.

Dominici and his colleagues reported in the BMJ that they analysed more than 95m insurance claims raised between 2000 and 2012 by hospital in-patients in the US who were aged 65 or more and enrolled in the Medicare programme.

They then looked at the air pollution, focusing on PM2.5 produced by vehicles and power stations etc. By analysing air quality data from various sources, they were able to estimate the PM2.5 levels for each patient on the basis of their home zip(pin) code.

The team compared air pollution levels for each patient during the two days around their hospital visit with levels from other points in time. This approach essentially takes into account factors such as age, socioeconomic status and even obesity, since it uses each patient as their own reference.

Fluctuations in air temperature and other factors were taken into account separately. The results backed previous studies that showed a link between short-term exposure to dirty air and conditions such as heart failure, pneumonia and heart attack.

The analysis suggests that even a small average rise in PM2.5 of 1 micrograms per cubic metre over a two-day period is linked to an increase of 68 older people per billion who were taken to hospital with heart failure the next day.

Put another way, the increase in air pollution raises the risk of such people ending in hospitals with heart failure by 0.14 per cent. The team also found that diseases that included septicaemia, Parkinson''s disease and urinary tract infections were also associated with poorer air quality.

Study author Yaguang Wei was quoted that the research suggested that the ill-health effects of PM2.5 were not restricted to individual organs. "It has a more systemic effect on multiple pathophysiological processes such as inflammation, infection, and water electrolyte balance," he said, although the details were unclear.

While the study cannot prove that air pollution causes the diseases, the team say it adds weight to calls for air pollution guidelines to be reviewed. Dr Ioannis Bakolis of King''s College London, who was not involved in the study, agreed. "These guidelines needs to be revised, as even the 9 per cent of the population that lives within the WHO limits may be substantially by affected by air pollution concentrations and its associated costs, according to the findings of the study."

However, the study has limitations, including that it looked only at one component of air pollution and only considered outdoor air pollution near patients'' homes.

It also did not account for short-term changes in behaviour that might have varied with air pollution levels - such as physical activity levels - while it is not clear if the results would hold in those not enrolled in Medicare, including younger people.

A team of experts from the University of Southampton say that there is much to learn, but one should not mistake knowledge gaps for paucity of evidence. "The sooner we act, the sooner the world''s population will reap the benefits."