Out of breath: How air pollution fuels viral infections, fever

  • Sanchita Sharma, Hindustan Times
  • Updated: Oct 17, 2015 18:16 IST
Air pollution hurts us in more insidious way than we realise . It fuels viral and bacterial infections in the winter months and is a major contributor to rising cases of colds, cough and viral fevers, including swine flu caused by the H1N1 influenza virus. (Virendra Singh Gosain/HT Photo)

Each year, an adult on average catches viral infections two to three times a year. Young children get them more often, falling ill between four and six times a year, with symptoms in both young and old ranging widely from mild sniffles and a sore throat to a hacking cough, high fever and acute diarrhoea, all of which appear to be leading to more and more hospitalisations each year.

Over the past two years, there’s also been a palpable increase in the frequency at which viruses and bacteria have been causing infection even among the healthiest of us. Doing everything right no longer ensures you will stay infection free, complained a friend who’s been fighting frustrating battles against frequent viral fevers despite leading an obsessively clean and healthy life. A typical day in his life is what most of us make New Year’s resolutions about – personal trainer, running, eating organic food, living in an ambience-controlled home and going for regular health check-ups – and yet he battles the same infections the rest of us with far more compromised lifestyle deal with.

In his case, urban air pollution appears to be the great leveller undermining his textbook robust immunity. The dense smog that hangs low across north India most of the year around does more than choke out the sun and starve our collective lungs of oxygen. It kills 6.2 lakh people prematurely in India from a wide range of seemingly unrelated diseases, including heart disease, stroke, chronic obstructive pulmonary disease, lung cancer, acute respiratory infections and asthma attacks, among others.

The death estimate from pollution in India in 2013 is a six-fold jump from the 1 lakh deaths estimated in 2000, said the Global Burden of Disease 2013, which tracks deaths and illnesses from all causes across the world. It’s the biggest cause of death after high blood pressure, indoor air pollution (mainly from smoking coal and food stoves), tobacco use, and poor nutrition.

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But most people don’t realise that air pollution also hurts us in more insidious way. It fuels viral and bacterial infections in the winter months and is a major contributor to rising cases of colds, cough and viral fevers, including swine flu caused by the H1N1 influenza virus. Airborne particulate matter are a deadly cocktail of dust, organic carbon, black carbon, nitrates and sulfates found in construction material, vehicular industrial emissions, incinerators, windblown dust, power plants and wood, coal, biomass and agricultural fires.

While studies linking air pollution with viral and bacterial infection in India are small and largely anecdotal, representative data from across the world firmly establishes the link.

An analysis of 10 European birth cohorts that between them used data from more than 16,000 children, established a link between air pollution and childhood pneumonia, painful middle-ear infection (otitis media) and croup, which is an upper airways infection that leads to children developing a harsh, barking cough because of inflammation around the vocal cords, windpipe and bronchial tubes. The study, published in the journal Environmental Health Perspectives last year, found oxides of nitrogen – byproducts of vehicular emissions, power plants and coal burning -- were the most harmful for young children.

Breathing polluted air every day may change a person's brain in ways that end up leading to cognitive impairment. (Shutterstock)

Viral identification data from positive identification count and outbreak records that included emergency visits for influenza-like illness, severe acute respiratory infection and meteorological factors/air pollution in the city of Porto Alegre in Brazil, from November 2008 to October 2010 showed that 22% of the close to 12,000 hospitalisations were triggered by air pollutants. The data, which was collated using time-series analysis and published in the Journal Influenza and other Respiratory Viruses showed that apart from the mean concentration of pollution, other related environmental factors that played a role were temperature, humidity and the duration of sunshine.

It’s no safer indoors. A study in the journal Inhalation Toxicology found dampness (marker for dust mites, endotoxins and reduced ventilation) and mould was consistently linked with respiratory symptoms of cough, wheezing, and upper respiratory infections.

Researchers at Geohealth Laboratory, University of Canterbury in New Zealand went a step further and used virology prediction tools to predict the numbers of hospital admissions. Writing in the Australian and New Zealand Journal of Public Health,they used various computational methodologies such as neural networks, theoretical computer algorithms and data mining techniques to study the relationship between air pollution, climate and hospital admissions and plan to predict and prevent potential outbreaks.

Cleaning the air is possible with legislation and public participation, as is predicting outbreaks and planning ahead. And the sooner we do it, the healthier we are likely to be.

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