Clearing the Air about Pollution
Clearing the Air about Pollution
Air pollution is gaining more media attention and concerning more people around the globe than ever before. But what are the main reasons for it, what problems does it cause and what can we do about it?
What causes air pollution?
Air pollution is the presence in the air of chemicals that can damage living things. Historically the main reason for air pollution was from burning fossil fuels but these days the biggest threat to clean air is traffic emissions. Cars, motorbikes, buses and vans chug out carbon monoxide, particulates, nitrogen oxides and hydrocarbons which are potential threats to health. To make matters worse, when many of these chemicals are exposed to sunlight, ozone, a secondary pollutant is produced.
In city centres, tall buildings create a kind of canyon effect trapping pollution and heat thereby increasing air pollution. Levels of air pollution rise and fall with the seasons; rain has a flushing effect, in effect flushing the air clean whilst warmer dryer weather leads to increased air pollution.
What problems does it cause?
As with many health issues, the people most under threat from air pollution are young people, as their lungs are still developing, the elderly and people with existing health issues, such as asthmatics or those with lung or heart conditions. Air pollutants also cause nose and eye irritation leading to protective membranes drying out and making people more susceptible to other infections.
Particulates are generally seen as the most dangerous of all the air pollutants; some estimates have suggested that they are responsible for up to 10,000 premature deaths in the UK. Particulates are a complex mixture of different substances but are largely soot. In towns and cities, the main producer of particulates is diesel engines which are less efficient than petrol engines. They are even less efficient when there is queuing stop/start traffic.
Particulates are measured in micrometres and commonly referred to as PM – particulate matter. The most dangerous are the PM2.5 (2.5 micrometres or less, approximately 3% of the diameter of a human hair) particulates as their minute size allows them to penetrate deep into the lung and potentially cause damage. Larger particles can be naturally filtered out by the body so whilst they cause irritation they are less harmful. Particulates have also been found to be carcinogenic in laboratory tests as they contain mainly unburned fuel oil and hydrocarbons.
Ozone can reduce lung function and irritate the respiratory tract particularly for asthmatics and permanent damage can occur if ozone is present in especially high quantities.
What can we do to improve air quality?
As vehicle emissions are the main reason for pollution, reducing the number of vehicles on the roads would be the natural way to reduce air pollution. Travelling by buses or trains would reduce the number of cars as would carpooling, where several people travel together in one car.
As air pollution is spread by the wind, moving car parks away from people would also reduce the risks of pollution.
Improving the flow of traffic, allowing cars to travel without stop-start queues makes them more efficient and pollute less. Similarly, encouraging the maintenance of vehicle engines would make them burn more cleanly and produce fewer emissions.
Trees improve air quality as they act as a filter to pollutants. They absorb particulate matter as well as ozone and nitrogen oxides.
These days, monitoring air quality is becoming more common. Organisations buy equipment that measures air quality and people can be alerted when air pollution levels are dangerously high. Generally the measurements given are the Air Quality Index (AQI) which communicates the overall air quality and PM 2.5 levels.
Harrow International School Bangkok have an air quality monitoring machine. This device checks the level of pollution every two minutes and automatic email alerts are sent to staff if the air quality changes. The school can then follow their air policy and decide whether to take precautionary action such as to keep students in at lunchtimes or break time or cancel outdoor sport activities.