Smog is one type of outdoor air pollution that can cause particular problems for people with existing health problems, including chest, lung or heart complaints. Outdoor air pollution could be responsible for 3.3 million premature deaths across the globe every year, according to recent research published in the scientific journal, Nature.
What is smog?
Smog is a dense layer of stagnant air which forms near ground level when air pollution is high. 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 associated with summer, winter smog can also occur. Cold foggy days are a particular problem as harmful gases can get trapped near the ground.
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). Ozone, which protects our skin from harmful UV rays when it’s high in the atmosphere, can be harmful and cause irritating health effects when it’s nearer the ground.
How does smog affect your 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. Environmental factors can also impact other conditions, such as fibrosing alveolitis and COPD (chronic obstructive pulmonary disease).
In some cities, like Beijing and New Dehli, smog is a regular and ongoing concern and for those exposed to it on a daily basis, it can be more harmful to health. The World Health Organisation recommends reducing air pollution in order to reduce stroke, heart disease, lung cancer, and chronic and acute breathing conditions.
How can you protect yourself from smog?
If you have respiratory issues that are affected by smog and air pollution – or simply want to protect yourself or your children from the potential health effects – here are some practical tips to help you:
- 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. The Department for Environment, Food and Rural Affairs (DEFRA) also has the latest information and includes a useful colour-coded summary of the current situation in all areas of the UK. 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.
- If the air quality forecast is poor, where possible, avoid the affected areas. If this is too difficult, stay indoors and keep your windows closed.
- Avoid exercising in smoggy conditions, particularly at midday when ground ozone levels are at their highest. Try to change the times you exercise to morning or evening (avoiding rush hour), or exercise inside.
- If you’re asthmatic or have COPD, carry your inhaler at all times. 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 so keep your windows closed. Airports, seaports and industrial areas also tend to have high levels of pollutants so avoid these too.
- If you’re walking or cycling to work, plan a route that avoids too many areas that are built up or congested.
- 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.
How does smog affect your health
Take a look at these sources for the latest on air pollution and how it may affect your health:
Asthma UK - www.asthma.org.uk
Air Quality website - www.airquality.co.uk
Defra (Department for Environment, Food and Rural Affairs) - uk-air.defra.gov.uk/latest
European Environment Agency - www.eea.europa.eu/maps/ozone/map
World Health Organisation
British Lung Foundation - www.lunguk.org