Standard Air Quality measurements use PM 10 particle size mass as a base measurement.
Recently PM 2.5 standard as a test measurement size has been adopted by testing authorities. Because it is particles at this size and below which can be breathed in to the human lungs. Growing research is showing that these particles may lead to a high incidence of Cancer.
If we allow government to only use particle size (mass) as safe limit for humans it is deceptive to say the least. We as a community must no longer accept this methodology and must demand that air quality be quoted in particle numbers in a given volume.
DIAGRAM and TEXT below FROM
FINE PARTICLES IN THE AIR: WHY ARE THEY A PROBLEM?
LIDIA MORAWSKA MSc. PhD
Queensland University of Technology
ABSTRACT
"Airborne particle pollution has been emerging as a global problem with growing scientific evidence linking increased health risk to exposure to particles in general, and, specifically to fine particles. Despite the significant increase in national and international efforts towards extending our understanding of various aspects related to airborne particles there is still very little information available on the production rate, airborne concentrations, fate of fine and ultra fine particles in the air, on the exposure-response relationship and on the mechanisms by which the particles induce the range of health effects. One important reason for the current difficulties relates to the scientific complexity of investigations on fine particulate matter at all levels of approaches, including: instrumentation, measurement and modelling, model validation and data interpretation and exposure assessment and risk quantification. Despite the current deficiencies in knowledge there is, however, the need for overcoming many of the problems related to fine airborne particles now, without waiting for future answers. This obviously creates a high degree of difficulty. How to proceed then?"
FIGURE 1
NUMBER OF PARTICLES
MASS OF PARTICLES
"Figure 1 Typical measured urban air particle number size distribution (upper diagram), and mass distribution (lower diagram) calculated from the number distribution.It can be seen from Figure 1 that the peak in the number distribution spectrum appears in the area where there is almost no mass in the mass distribution spectrum and vice versa, the peak in the mass distribution spectrum is where the particle number is very low."
