Fine particulates, nitrogen oxides and sulfur oxides can affect the health of human beings if present in the air in sufficient quantities.  These contaminants are regulated by air quality standards in both Australia and New Zealand, and are common subjects of air quality impact asessments due to ther presence in many types of discharges.  Most urban and industrial airsheds contain some level of concentration of these substances, and this must be taken into account when carrying out an air quaity assessment. 



When considering the impacts of fine particulates, the portion that poses the greatest potential health effect is particulate less than 10 µm in diameter, and the subfraction less than 2.5 µm in diameter (known as PM10 and PM2.5).  Ambient concentrations of the PM10 fraction are controlled by national standards and State/regional regulations in both Australia and New Zealand.  Guidelines are also in place for PM2.5 concentrations, and standards for PM2.5 are unlikely to be far away.

Larger particles can cause nuisance effects through dust deposition onto surfaces.  For more information about how Air Quality Professionals can provide clients with expertise around the nuisance impacts of particulate deposition, click here.

Sulphur oxides and nitrogen oxides can be present in the air as different oxides, such as sulfur dioxide (SO2), sulfur trioxide (SO3), nitric oxide (NO), nitrogen dioxide (NO2), or nitrous oxide (N2O).  Each of these oxides has a different impact on human and plant health, and only some of the oxides are regulated by air quality standards.  The oxides can transform in the atmosphere after being discharged at a source.  For example, NO transforms to NO2 in the air in the presence of ozone.  Predicting rates of transformation is complex and a number of different techniques are available.



​Services provided by Air Quality Professionals in investigation of fine particulate, NOx and SOx issues include the following:

■  Scoping of issues to determine extent of 

    impacts and appropriate investigation strategies

■  Source apportionment – what are the main

    contributors to off-site concentrations

■  Targeted and strategic long term monitoring

    and control improvements plans

■  Stack testing and ambient monitoring


■  Atmospheric dispersion modelling


■  Stack height and diameter optimisation to

    maximise dispersion


■  Benchmarking/validation of model against

    known or measured impacts

■  Impact risk assessment interpreted from model


■  Emission control equipment options, and

    performance evaluation

■  Environmental Impact Statements

■  Works Approvals, Development & Planning


■  Licence conditions negotiations

■  Independent peer review of assessments

    prepared by others

■  Credible and experienced expert witness


We have experience in assessment of fine particulate, NOx and SOx discharges from a wide range of industrial activities and fuel burning processes, including:

power and steam generation
wastewater treatment


■  small and large scale diesel-fired standby power generation
■  coal-fired boilers
■  waste wood-fired boilers

■  natural gas-fired power generation

■  pulp & paper
■  fibreboard
■  lime & cement
■  cereals, milk powder, dry foods

■  superphosphate fertiliser

■  steam boilers

■  metal refining


■  biogas combustion
■  standby power generation

■  biosolids drying

■  licence reviews/approvals
■  evidence for prosecutions/defences
■  policy research and background


© Air Quality Professionals Pty Ltd, 2014