WMO scientists assess and monitor air pollutants such as ground-level ozone,smog, particulate matter, sulfur dioxide and carbon monoxide.

VOA: standard.2009.03.23

Ultrafine particulate matter refers to nanoscale particulate matter, smaller than 0.1 micron (100 nanometers) in size.

FORBES: Two New Reasons to Worry about Air Pollution: Obesity and Diabetes

It aims to establish a platform for exchange of knowledge with respect to methods for characterisation of colloidal and particulate matter in these systems and to cover the technological aspects of particulate matter in different water treatment processes such as drinking water, wastewater and landfill polluted waters.

UNESCO: Water Portal | Water Events Worldwide

While particulate matter emitted by vehicles make up a small part of overall particulate matter in China, in dense urban areas, it is almost certainly the highest contributor to human exposure of PM2.5, according to Vance Wagner, a senior researcher at the International Council on Clean Transportation.

WSJ: China's Pollution Fight Faces Resistance