Has Climate Change Increased Seasonal Allergies?


It may be good news for the makers of Kleenex and Claritin, but it’s bad news for us: a recent study suggests that severe seasonal changes may lead to higher levels of outdoor airborne allergens and increased allergy susceptibility among infants and babies in utero. This is especially true in industrialized nations.

Most common outdoor allergens, like tree pollen, grass pollen and mold, increase in production when temperatures and humidity are high. Ragweed levels in particular also go up with higher concentrations of atmospheric CO2 -- the “greenhouse gas” causing all the trouble with global climate change.

Higher temperatures have already resulted in earlier pollen seasons in different parts of the world: remember the El Nino of 1997-1998, with its relentless rain, worldwide death toll and massive property damage? The year after this infamous weather event, the mold high point occurred earlier than normal due to the previous season’s wet and warm conditions.

The study also examined research on the timing of allergy development before and during infancy. While exposure to allergens from birth to three months was the strongest indicator of future allergies, exposure prior to birth was connected as well.

So as the consequences of climate change -- higher temperatures, humidity and CO2 levels -- extend the pollen season, more babies may grow up with things like eczema, runny noses, watery eyes or worse: asthma. High pollen and mold counts lead to worsening of symptoms for asthma sufferers, and studies have shown more asthma-related emergency room visits and hospitalizations during these peak times.

For now, try some natural remedies for allergy symptoms such as a neti pot and an indoor air purifier. To help curb your kids’ asthma attacks (along with working out a plan with your doctor), try these surprising at-home tricks, or even an asthma “diet” (and definitely keep them off acetaminophen).

For later, learn what you can do about climate change.

More from FYI Living:

Temperature Changes Increase Allergies in Children
Seasonal allergies in children caused by airborne allergens are on the rise and the reasons for the phenomenon are still unclear. This review of previous literature found that this trend could be stopped if more was understood about environmental changes. The authors suggest, “Improved public-health strategies such as adequate humidity control, optimum air filtration and ventilation” and public awareness regarding prevention.

Increasingly, children all over the world are developing allergies and this is more common in developed and industrialized countries. These allergies in children are characterized by skin problems, like eczema, or may show up as sneezing, runny nose, asthma or hay fever. Studies have shown that these allergies in children may have a basis in inherited genes and also in the immediate environment of the child. There have been studies that looked at the allergic potential of air borne allergy inducers, or “aeroallergens.” These studies have mainly focused on aeroallergens that are present inside homes. There is little research on the allergic potential of airborne allergens outdoors; these include pollen and mold. These outdoor allergens also change with season, temperature and humidity of the air. This review looked at three important parameters –- seasonal variations in temperature and humidity, its relation with airborne allergens and the association of both with allergic ailments in children.

This review gathered previous evidence of studies that showed the risk of allergies in children (defined as those below 18 years of age) in relation to airborne allergens like pollen and mold that is found outdoors. The studies that looked into both the initiation, as well as an increase, in allergies in response to these allergens were included. Diseases included were eczema, runny nose, asthma and hay fever in children. Also, included in the review were studies that looked at allergen exposure before the child was born -- when the child was still in the mother’s womb.

• Results showed that there is concrete evidence that links seasonal changes and airborne allergy-inducing substances like pollen and mold.
• With the rise of these airborne allergens, there is a proportional rise of allergies in children and also an increasing risk of allergies as the children grew into adults.
• The results of the studies indicated that there are crucial windows of immunity and allergic development, both in the womb as well as during infancy.
• The authors concluded that allergens present within the house may change with the weather. However, it is the outdoor allergens that are more prone to change with the weather and thus linked to allergies in children.

Next steps/Shortcomings
The authors admit that there was a wide variation in the included studies. Most of the studies did not look at the actual exposure to pollen in each individual. Some studies included children who had parents with allergies. This skewed the results since many of them had inherited allergic tendencies. The authors suggest a better understanding of the seasonal changes in airborne allergens and also their impact on children.

This study shows that seasonal weather changes are associated with changes in airborne allergens like pollen and mold spores. These changes are further linked to rising trends of allergies in children. The authors suggest that there should be more preventive techniques that reduce the greenhouse gases and also prevent drastic changes in weather. They write that groups, such as public-health professionals, architects, city planners and emergency-preparedness agencies, should come together to improve public-health strategies. Climate change policies need to prevent excessive greenhouse gases from causing climate change. Some measures could include “optimum air filtration and ventilation.” Propagating public health messages is also important in order to prevent as well as recognize early symptoms of allergies in children.

For More Information:
Climate Change, Aeroallergens, and Pediatric Allergic Disease
Publication Journal: Mount Sinai Journal of Medicine, 2011
By Perry E. Sheffield; Kate R. Weinberger; Mount Sinai School of Medicine, New York, New York, and Columbia University, New York, New York

*FYI Living Lab Reports Are Summaries of the Original Research.