Respiratory diseases related to allergies, including hay fever and asthma, are increasing worldwide. A recent medical article blames urban air pollution and climate change for much of this increase. The Intergovernmental Panel on Climate Change reported in 2007 that greenhouse gases and global temperatures have been rising for the past 30 years, mostly due to human activity including automobile traffic. Automobile emissions affect respiratory conditions both directly and through their influence on the weather.
Air pollution components that have the worst effects on respiratory disease include:
1. Nitrogen dioxide
2. Ozone
3. Sulfur dioxide
4. Fungal spores
5. Pollens and other plant-derived particles
6. Diesel exhaust particles
Reference 1 reports estimates that 50 percent of the population of the United States live with nitrogen, ozone, sulfur dioxide, and particulate pollution that exceed the standards set by the Environmental Protection Agency. Air pollution is associated with asthma exacerbations, resulting in increased medication use and more visits to hospital emergency rooms. The authors of Reference 1 suggest that air pollution may aggravate allergic responses to allergens such as pollen. Interaction between pollutants (such as ozone) and plant particles may cause the release of more allergens. Pollutants may also sensitize the airway epithelium, causing greater responsiveness to allergens.
The role of the weather on respiratory allergy symptoms is still poorly understood. Elevated temperatures and carbon dioxide concentrations in the atmosphere increase plant growth rates. Climate change is expected to influence the distribution patterns of pollen, fungal spores, and other plant-derived allergens. Weed species are expected to proliferate. In addition, UV radiation in polluted urban atmospheres increase the formation of ozone. Some studies show that in urban areas, asthma symptoms are more common in warmer climates than in cooler ones.
Extreme weather events and thunderstorms are part of the predicted climate change that we have to deal with over the next few decades. There is some evidence that thunderstorms increase the rate of allergic asthma, possibly from their effects on redistributing allergenic particles and rupturing pollens from osmotic shock.
There are numerous proposals for protecting our environment from detrimental climate change; everything from electric cars to artificial volcanoes injecting sulfur compounds into the stratosphere. Every option has its price. In calculating the benefits, we need to keep in mind that health costs from asthma and allergies count too.
Reference:
1. D'Amato G et al, “Urban air pollution and climate change as environmental risk factors of respiratory allergy: An update”, J Investig Allergol Clin Immunol 2010; 20(2): 95-102.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.