New air quality research indicates that measuring ultra-fine particles can distinguish between particles generated through human activities, such as combustion, and larger particles, which are more likely to arise from mechanical processes and natural sources.
The smallest air particles are from combustion sources such as vehicles and power plants, and easily enter the body. However, air quality measurements today typically focus on larger particles from mechanical processes, which may be less relevant from a health perspective.
Air quality standards in Europe measure the amount of particles in the air that are less than 2.5 (PM2.5) and 10 (PM10) micrometres in diameter. The limitations of the measurement equipment available at the time were at least partly responsible for the choice of these particle sizes.
Research using data on over 6000 particle samples from a range of environments explored whether measuring PM1 and PM10 levels would lead to a better distinction between the different types of pollution source.
The research found that PM2.5 data were hard to interpret, because they included particles from both mechanical processes and from burning (of fuel, for example). Data from many environments around the world showed a clear cut-off point around the PM1 mark, with particles below this size being derived almost exclusively from burning. This suggests that PM1 and PM10 would be more useful measures of air quality than the current system.
This article was taken from the Science for Environment Policy, a service from the European Commission.