Health

Air pollution - should you be worried?

February 19th 2017 / Ayesha Muttucumaru Google+ Ayesha Muttucumaru

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Could breaches of pollution limits mean we’re heading towards a public health crisis? We spoke to the experts to find out

Should you be worried about air pollution? With the spotlight on our air quality being shone brighter than ever before, all markers point to yes - for those both young and old.

Last month, the Mayor of London Sadiq Khan issued his first ‘very high’ air pollution alert for the capital. Is it just a passing problem or is it a growing crisis that could have short and long-term consequences for our health? We found out.

What are the signs that poor air quality is affecting you?

Short-term, the signs may not be immediately obvious. “It’s a very difficult question to answer,” says Professor Jonathan Grigg, Professor of Paediatric Respiratory and Environmental Medicine at Queen Mary University of London on behalf of the Healthy Lungs for Life campaign. “The problem in a way is that most of us are healthy and are not going to experience short-term effects of poor air quality - or ones that we’ll notice. Healthy lungs have a lot of reserve.” Those most likely to experience immediate adverse short-term effects of high pollution are people with previous health problems. “A healthy person walking on a busy road on a regular basis won’t notice much - mild irritation, coughing perhaps - quite trivial things. However for people who are vulnerable (those who have an established disease for example), there are epidemiological studies that show an association between high pollution levels and increased symptoms if they suffer from asthma or are vulnerable to heart attacks.”

In order to gain a better understanding of the full spectrum of risks, a distinction should be made between short and long-term exposure to air pollution, points out Professor Grigg. “Short-term exposure may occur because of a high pollution day across the whole of London where for example, air pollution has been blown in from other areas or there isn’t any wind blowing it away,” he explains. “Other exposure may be longer term, determined by the length of time spent near main or heavily used roads and traffic. The day-to-day effect.”

It is this longer-term exposure which gives rise to a range of more serious health concerns. “The long-term effects are subtle, such as reduced lung function and the development of new onset asthma,” he cautions. “Later on, the day-to-day long-term effects can lead to an increase in susceptibility to cardiovascular disease.” The risks can also extend to types of lung cancers too. “We’re seeing the development of lung cancer in non-smokers, which accounts for a quarter of cases, where certain air pollution types are contributors,” he highlights. “The World Health Organisation has classified diesel as a type 1 carcinogen. However, if you’re a smoker and develop lung cancer, that would be the overwhelming cause - if not, there’s a strong link.”

What levels are we regularly exposed to?

To take a first-hand look at the effect of air pollution in the capital on a regular day, Dr Michael Mosley teamed up with King’s College London on his show, Trust Me I’m a Doctor, to track his exposure. Equipped with a kit to measure black carbon levels from diesel cars and particulate matter (aka PM, extremely small particles that penetrate deep into the lungs and can lead to long-term problems), he set out on a five mile walk (taking a busy road to his destination and quieter back streets back) to see if his levels really warranted concern. Unsurprisingly, his exposure was high on the way there, but reassuringly his levels dropped dramatically on his way back. The most surprising twist though was the high spike noticed at the end of Dr Mosley’s journey when he was in a taxi. Due to the high traffic, the fumes from the vehicle directly in front went straight into the car, raising his levels and illustrating the point that his increased exposure was more due to the vehicles surrounding him rather than the vehicle that he was in himself.

Short-term, the effects were inconsequential. However, regular exposure to these smaller particles was noted of greater concern longer term in the analysis afterwards due to their smaller size and ability to penetrate deeper into the lungs when inhaled. As Professor Frank Kelly told Dr Mosley, “They are carriers of a complex set of chemicals on their surface. These chemicals then will interact with the blood vessel walls and they’ll set up reactions which over a long period of time damage those walls, which we associate with heart disease.” It for this reason also that the risk of developing diabetes is also increased and worryingly, also neurodegenerative diseases such as Alzheimer’s due to damage to blood vessels in the brain. Studies were also highlighted by Professor Kelly to show an increased susceptibility to strokes too.

Are the dangers just confined to cars and roads? According to a new study from The University of Surrey, they unfortunately also extend to the Tube too. According to its findings, commuters are exposed to more pollutants when train windows are open - specifically, 68mg of harmful pollutant PM10 compared to 8.2mg for car drivers. The Tube lines most affected? The Victoria and Northern lines, where it was found that opened windows intensified the effect of pollutants when going through tunnels. That being said though, while drivers aren’t exposed to as many pollutants, cars were found to emit pollutants which were more harmful to thereby cause more harm to the environment. As for the bus, the news was pretty bleak too, with the study showing that commuters were exposed to an average of 38mg of PM10, approximately half as much as Tube passengers but five times as much as cars.

subtle and small changes in direction over long periods of time can lead to major differences later on

Is it putting children’s lung development at risk?

According to Professor Grigg, the risks aren’t just reserved for the older generation, but also pose significant problems for the younger generation too. “We’re pretty certain that young children are more vulnerable as they are developing and it can deviate the trajectory of lung function growth,” he explains. “These subtle and small changes in direction over long periods of time can lead to major differences later on.”

Are these cases on the increase? “In the UK, we haven’t done any long studies on the subject,” says Professor Grigg. “The gold standard would be if were able to measure the lung function of a group of children aged 8 or 9 and follow it up over 10 years. We have seen this in California though and are starting to at least obtain cross-sectional data for children in high and low pollution areas in London where we’re seeing similar patterns and differences in lung function.”

Long-term, the consequences could be irreversible. As highlighted by Professor Kelly, lung growth stops at 18, after which point, those affected won’t be able to recover the capacity lost, a finding that they’ve found in London, the US and China.

Should you stop exercising outdoors?

Not necessarily. While caution should certainly be exercised on days of high pollution, (find more information here), there are ways to help minimise your risk to the negative side-effects on a day-to-day basis. “Don’t stop,’ advises Professor Guy Joos, President of the European Respiratory Society, on behalf of the Healthy Lungs for Life campaign. “The health risks associated with breathing in air pollution while exercising are significantly less than those of an inactive lifestyle.” Here are his top tips:

1) Be aware: “When you are physically active, you breathe more often and take more air into your lungs, you also tend to breathe through your mouth not your nose, which means you’re less able to filter out pollutants.”

2) Consider your location and route: “When exercising in a town or city, make use of parks, public spaces and trails with low emissions zones.”

3) Avoid busy roads with high buildings: “Air pollution tends to get trapped within roads with tall buildings on either side.”

4) Avoid exercising during rush hour – “And be wary of traffic lights, when vehicles move away from lights they give off more emissions.”

5) Keep a healthy distance from the road: “You will be exposed to lower levels of air pollution just 1-2m away from the main flow of traffic.”

6) Check the air quality index of the day in your area: “Actual air pollution levels depend on the type of pollutant, the location and the local weather.” To check the levels in your area, visit the DEFRA Air Pollution Forecast Map here.

7) Don’t get stuck behind vehicles: “When cycling or jogging behind other vehicles, you will breathe in very high levels of pollutants - move round them if it is safe to do so.”

8) Check the weather forecast: “Air pollution tends to be at its highest on hot, sunny days, for example, so you could plan your exercise for the morning when pollution levels are lower,” points out Professor Joos, with certain climatic factors giving rise to great risk.

How so? According to the Met Office, “Pollutants such as sulphur dioxide, nitrogen oxides and particulate matter are routinely released into the atmosphere as a result of the combustion of fossil fuels and industrial processes. Chemical interactions amongst these primary pollutants, under the influence of heat and sunshine, can give rise to additional secondary pollutants, such as ozone.” Fog and wind also have pivotal roles. “Also the strength of wind and direction also play a big part - lighter winds mean pollutants will be less likely to be dispersed and so may grow in concentration, especially near their source. The direction from which the wind comes from can also lead to pollutants being brought in or blown away from an area. When winds are light, there is also an increased chance of fog which can be helped to form by pollution particles.”

9) Don’t forget indoor air pollution: “If you exercise at home, for example, don’t do so after cleaning as vacuuming and some cleaning products can reduce air quality,” cautions Professor Joos.

I will try and stick to quieter back streets because I’m now convinced that that will make a big difference

What can you do to reduce your exposure on your commute?

To ensure you’re best prepared, having a plan of action in place for days where high pollution alerts are issued could prove fruitful. “Have a plan, don’t be taken by surprise,” recommends Professor Grigg. “If it’s a high pollution day, see if you can work from home or if you’re planning to walk around the city, see if you can reduce your time outside.” He adds, “If you are vulnerable, seek advice from the PHE website.”

On a day-to-day basis, Dr Michael Mosley concluded that active travel which involved taking back streets was the best option for both protecting his health and the environment. “I was particularly shocked by the amount of bad stuff I was inhaling while I was in that taxi when it was in high traffic,” he commented. “In the future, I will continue to walk and cycle where I can in London because I enjoy it and because it’s good for my heart and lungs. But I will try and stick to quieter back streets because I’m now convinced that that will make a big difference.”

While cycling or walking to work would be the dream, for most it’s unfortunately not a viable option - especially if they’re having to commute from afar. What is needed on a wider and longer term scale is further action from a legislative and regulatory level. “We first need to reduce the diesel emissions on our roads which act as a major contributor to the levels of nitrogen dioxide,” says Professor Grigg, a step which London Mayor Sadiq Khan highlighted as key in his statement regarding high pollution levels in the capital in January. “We’re delivering the strongest emission measures to clean up our bus fleets, charging for the dirtiest most toxic diesels, and bringing forward and then extending the Ultra Low Emission Zone.” He added, “The government urgently need to do their bit. They need to devolve more powers to London and introduce a national diesel scrappage scheme to rid our streets of the dirtiest vehicles. They also need to reform vehicle excise duty and bring in a new Clean Air Act that finally tackles this problem and means that Londoners don’t have to be afraid of the air we breathe.”

And the Tube? According to Dr Prashant Kumar who led the study by the University of Surrey into PM exposure on trains mentioned earlier, greater investment is needed to modify carriages to best protect their passengers. He commented: “The relatively new airtight trains with closed windows showed a significant difference to the levels of particles people are exposed to over time, suggesting that operators should consider this aspect during any upgrade of Underground trains, along with the ways to improve ventilation in Underground tunnels.”

Sounds promising and time couldn’t be more pressing with the European Commission having just issued a ‘final warning’ over breaches of air pollution limits to the UK. However, the problems aren’t just confined to London, with Birmingham, Leeds and Glasgow also featuring in the top 16 areas. According to DEFRA and a Government spokesperson, “We are firmly committed to improving the UK’s air quality and cutting harmful emissions. That's why we have committed more than £2billion since 2011 to increase the uptake of ultra-low emissions vehicles, support greener transport schemes and set out how we will improve air quality through a new programme of Clean Air Zones. In addition, in the Autumn Statement, we announced a further £290m to support electric vehicles, low emission buses and taxis, and alternative fuels. We will update our air quality plans in the spring to further improve the nation’s air quality.”

In his mission to help reduce toxicity levels, the Mayor recently tweeted about two new green, electric bus routes to help cut air pollution in the city. Speaking to the Evening Standard he commented: “It will take the total number of electric buses on the capital’s streets to more than 120, in addition to 2,000 hybrid electric buses – 20 per cent of the whole fleet - already in operation. TfL plans to stop buying diesel-only double decker buses completely by 2018 and wants more than 3,100 of them to be hybrids by the following year.” He added, “More than half of London’s toxic air pollution is caused by road transport, and our oldest buses are one of the biggest contributors to harmful NOx emissions in central London. These new electric buses will eradicate harmful emissions and will have a significant impact on the quality of our air.”

Hopefully those in power on a national and global scale will take heed from Sadiq Khan’s lead: “I want London to become a world leader in hydrogen and electric bus technology and I hope other cities around the world will join me in sending the message that only the cleanest technologies are welcome where we live and work.” Here’s hoping more cities start to clean up their acts.

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