Medical articles

Our resident medical experts tackle a range of different topics in this growing collection features and articles.

Protect yourself against the effects of smog

Tags:

smog respiratory pollution emmisions breathing asthma

Smog and air quality issues can occur throughout the year, causing problems for people with respiratory conditions. GP Dr Alasdair R Wright explains how smog can affect your health and what you can do to protect yourself.

What is smog?

“Smog is a dense layer of stagnant air which forms near ground level when air pollution is high,” explains Dr Wright; “it is more common in built-up cities with dense traffic or in areas near industry with high emissions.”

This harmful substance is created when sunlight reacts with gases, such as industrial emissions or car exhaust fumes, in the lower atmosphere. The high-pressure warm weather systems that we get on hot days tend to be slow moving, so they trap the polluted air at a low level in the atmosphere.

But, although smog is typically associated with summer, it’s not just a summer problem. In fact, it can be equally prevalent during the winter months. Cold foggy days are a particular problem as “cool packets of air trap the harmful gases near to the ground”.

“Although the ozone layer helps protect our skin from harmful UV rays when it’s high in the atmosphere, when it’s nearer the ground it can be harmful and cause irritating health effects.

“Smog is made up mainly of ozone but it also contains other harmful substances, such as sulphur dioxide, nitrogen dioxide, carbon monoxide and PM10s (small molecules which can find their way deep into our lungs),” adds Dr Wright.

How smog affects health

Some people are more sensitive to the effects of smog and air pollution than others, including those with existing chest, lung or heart complaints. The first health signs of smog may be irritation in the throat, nose, eyes or lungs and breathing may be affected.

According to Asthma UK, about two thirds of people with asthma find that pollution triggers their symptoms. High levels of pollution have been linked to an increased risk of asthma attacks and low peak-flow readings, so it’s important for asthmatics to keep their inhalers at hand during smog attacks.

In some parts of the world, city smog is a regular and ongoing concern and, for those exposed to it on a daily basis, it can be more harmful to health.

Research carried out at the University of California, for example, looked at the effects on nearly 450,000 people of living in highly smog-polluted cities. They found that chronic exposure to ozone and smog in areas with the highest concentrations resulted in a 25 per cent to 35 per cent greater risk of dying.

Practical steps to protect yourself

If you have respiratory problems and are affected by smog and air pollution, or are keen to protect yourself or your children from potential health effects, there are practical steps you can take.

Here are Dr Wright’s top tips.

Watch the weather forecast and check daily air quality reports if you live in a city or an area that is particularly congested with traffic.
If the air quality forecast is poor, stay indoors and keep your windows closed - or, where possible, avoid the affected areas.
Avoid exercising in smoggy conditions, particularly at midday when ground ozone levels are at their highest.
If you’re asthmatic or have COPD (chronic obstructive pulmonary disease), carry inhalers at all times. If smog is bad, treatment may need to be increased for a while. If you notice any rapid deterioration in your condition, consult your doctor.
If you have respiratory conditions and need to travel on smoggy days, avoid congested areas where you may get stuck in traffic jams. Road junctions can be a hotbed of exhaust emissions. Keep your windows closed.
If you’re walking or cycling to work, plan a route that avoids too many areas that are built up or congested with cars.
Keep your own emissions to a minimum. Avoid unnecessary car journeys in cities, don’t rev up or leave your engine running for a long time outside your home on cold days or when stuck in traffic jams.

Keeping an eye on air quality

If you’ve got respiratory problems and are affected by smog, it’s important to keep up to date with weather forecasts and smog throughout the year. You can find a daily update on air quality at the Air Quality website.

Defra (The Department for Environment, Food and Rural Affairs) has the latest information about air pollution on its website too. This includes a useful colour-coded summary of the current situation in all areas of the UK. The ratings go from low (green), to moderate (yellow), to high (red) and to very high (purple).

If you’re travelling and want to know about how smog might affect you in Europe, the European Environment Agency maintains an ozone map on its website.