Clean, pure air – at the top of a mountain, in a forest, on the beach, in the country – invigorates with every breath. Yet as the quality of our air is increasingly affected by pollution, the effects of climate change are becoming more apparent.
The negative health impact of air pollution is well established. Pollution penetrates the mucosal barrier of the lungs, causing inflammation and allergic airway responses. Air pollution, in turn, is highly affected by weather and climate conditions. However, just how weather and climatic changes of global warming influence air quality and consequently human health is difficult to predict, and it is currently the subject of much research and debate in scientific circles.
Climate change is expected to increase regional ambient concentrations of ozone and fine particulate matter. This is significant, as these pollutants can directly cause respiratory disease or exacerbate existing respiratory disease in susceptible individuals. The health impacts of ozone and fine particles are well documented.
Majority of Australian’s become familiar with ozone we were burning through our ozone layer at an alarming rate, leading to the ban on CFC’s in industry and aerosols in the 90’s. But there is more to the ozone story. Ozone itself is formed in warm, polluted air in the presence of sunlight. The key precursors are nitrogen oxides and volatile organic compounds, both emitted by the burning of fossil fuels. Breathing ozone has been shown to cause inflammation in the deep lungs, reversible lung injury, and to worsen chronic obstructive pulmonary disease, asthma and rhinitis.
Population studies of people living in polluted areas have suggested that ozone may increase the risk of asthma-related hospital visits and even premature mortality. The risk is increased for people engaged in physical exertion outside while ozone levels are high, as more ozone is breathed into the lungs, making children, athletes and outdoor labourers at a greater risk of experiencing these affects. Current climate change predictions are warning of increased concentrations of ‘ground-level’ ozone in some areas and subsequent increases in related respiratory illness.
Fine particulate matter, or PM2.5, is a complex mixture of solid and liquid particles that are less than 2.5 mg in diameter. PM2.5’s are emitted by a range of sources, but large quantities are produced as fossil fuels are burnt. Elevated PM2.5 levels are associated with respiratory and cardiovascular disease, including asthma and chronic obstructive pulmonary disease. Although the health risks of PM2.5 are well recognised, just how climate change will affect PM2.5 is unknown – something scientists are keenly trying to uncover. What is known is that PM2.5 formation is partly influenced by humidity and temperature, and the greater the temperature, the greater the health impact.
In my previous article, I explored the impacts of climate change on aeroallergens such as pollen. Ozone and PM2.5. also have the potential to alter the allergenicity of aeroallergens like pollen, causing further airway sensitisation.
This all may sound scary, yet as there are so many variables, much more study is needed to evaluate the potential affects of climate change. Only with understanding can our scientists and leaders develop strategies to protect those most vulnerable.
References available on request