Browning said it may be the level of trust in neighborhoods that is the key factor in collective efficacy that influences asthma levels. People who live in areas where they don’t trust their neighbors are probably exposed to high levels of indoor allergens.
“If residents feel uncomfortable walking outside or leaving windows open for fresh air, they may be continually exposed to high levels of indoors allergens such as dust mites or cockroaches,” he said.
I can see that. I have read more about this as a cause of asthma:
Digging The Dirt On Asthma
The rise in childhood asthma across the Western world has prompted researchers to look for factors that could be causing the increase. One theory suggests that Western households are too clean, and that the lack of exposure to viral infections and other nasties is leaving our children with a deficient immune system. Scientists call this the 'hygiene hypothesis.' They contend that because of a lack of exposure to viruses and other environmental factors, children are not able to build up resistance, and can become more susceptible to disease.
Professor Peter Openshaw, from Imperial College London, explained that a lack of exposure to dirt and common viral infections among children could be behind the rise in the levels of asthma. "Although we have seen a dramatic decline in many previously common childhood infections over the past 100 years, we have also seen a considerable rise in the prevalence of diseases such as asthma. The increase in asthma cannot be blamed purely on changes in genetic risk, so must be down to environmental factors."
"The challenge now is to find ways of reproducing the protective effects of early childhood infections, while reducing the burden of actually getting these infectious diseases. Knowing exactly which 'dirt' provides the best education for the immune system, and how to mimic its affects in a cleaner environment, could be the key to reducing the rise in the prevalence of asthma and related diseases," he added.
Now the race is on to identify which types of dirt provide the best 'education' for the immune system. The right answers could be an important step in providing new treatments for diseases such as asthma. Studies have shown that most common colds can help protect against wheezing in later childhood, and other childhood infections such as chickenpox also provide a level of protection. Other aspects of the 'hygiene hypothesis' suggest that having many older siblings, attending day care at an early age, or growing up on a farm can help in promoting resistance to disease.
So, until scientists identify the 'magic dirt', it may be beneficial not to worry too much about how dirty the kids get!
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