A Review of Recent Literature Investigating the Measurement of Automotive Particulate; The Relationship with Environmental Aerosol, Air Quality and Health Effects

Levels of ambient particulate matter have become the focus of increased attention over recent years as a result of studies suggesting an association between exposure and adverse health effects. Whilst research is continuing in many areas to identify a biological mechanism whereby this association can be explained, as yet there are only hypotheses. Causal relationships between observed health effects (i.e. increased hospital admissions, mortality, respiratory or heart problems) and any specific characteristic of the ambient aerosol have yet to be confirmed.

Ambient aerosol has a complex chemistry and a wide range of physical properties, most of which undergo constant modification or transformation within the atmosphere. The particles in this aerosol may have originated either from natural or anthropogenic sources and may be either primary emissions (i.e. directly emitted to the atmosphere as particles) or secondary particles - formed by reaction of gas phase components. The extent of the contribution to the total aerosol from the variety of different sources, of which traffic emissions are one, will vary from locality to locality, seasonally and diurnally and be affected by weather conditions and local sources.

This paper presents literature relating to the detailed measurement of automotive particulate, with respect to mass and number and the related size distribution. Measurement techniques and sampling strategies are described and potential inaccuracies noted. Difficulties currently inherent in assessing any impact of automotive particulate on ambient air quality and/or health issues are illustrated and a range of research targets suggested by which more effective progress may be facilitated in this complex topic area. Conclusions are drawn that reflect the need for improved understanding to support rational decision making.