AIR POLLUTION IN METROPOLIAN PERTH AND CARDIOVASCULAR AND RESPIRATORY HOSPITAL ADMISSIONS

Abstract

Background: Perth is the capital of Western Australia with a population of over 2 million people. It is generally regarded as having ‘good’ air quality with levels of criteria pollutants usually well below Australian Air Quality Standards (AAQ NEPM). Most exceedances are in discrete areas and associated with bushfires during the warmer months. There is increasing evidence from both Australian and international research that many of the health effects that are attributed to exposure to high levels of air pollutants also occur when people are exposed to levels below national standards, leading to questions about whether the standards are in fact ‘too high’.

Aim: To determine whether unscheduled hospital admission rates in the Perth metropolitan airshed were affected by low levels of pollutants in an airshed with ‘good’ air quality.

Methods: Historical daily ambient air quality for carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), PM_2.5 and PM₁₀ over a 10-year period were accessed from air monitoring stations throughout the metropolitan area.  Hospital admission data for respiratory and cardiovascular cases from all general hospitals in the same geographical area and over the same time period was also obtained.  Mean monitored levels of pollutants were divided into thirds or tertiles representing increasing levels of exposure. Logistic regression was performed on all possible combinations of tertiles, illness condition and hospitalization increase.  

Results: Significant relationships were found between levels of CO, NO₂ and O₃ and increases in hospital admissions for various conditions and various combinations of covariates in the second and third tertiles. There were however no significant relationships between PM₁₀ and hospitalizations for any illness and PM_2.5 was only found to have a significant relationship with asthma admissions.

Conclusion(s): In urban areas that are considered to have ‘good air quality,  low levels of pollutants may still have a detrimental effect on the rate of cardiovascular and respiratory hospital admissions. The results of this study provide further justification for lowering the maximum levels of pollutants specified in the AAQ NEPM.

Presenter e-mail: t.hannelly@curtin.edu.au