Why Does Weather Affect Psoriasis and Other Medical Conditions?

I have been trying to think about why weather might affect psoriasis, psoriatic arthritis, and other medical conditions. Is it just the amount of sunlight? Do the changes in air temperature and pressure affect processes in the body in some way? I have another thought about that:

What if it is related  to microbes?

The air that we breathe is loaded with microbes:

Andersen and his colleagues used a DNA micro-array to probe air samples for a gene involved in producing a protein, called 16S rRNA, that is found in all bacteria.…

The test found evidence of more than 1,800 types of airborne bacteria. It also showed that location is not as important as the time of year and weather for predicting microbial diversity than location. For example, during warmer and dryer conditions they found increased levels of spore-forming bacteria.

It is interesting that not only does the weather affect the microbe composition, but the microbe composition affects the weather.

Could breathing or ingesting these microbes have any effect on human health?

There seems to be a link between microbes and psoriasis:

Our results indicate that psoriasis induces physiological changes both at the lesion site and at the systemic level, which select for specific differential microbiota among the assayed clinical skin types. These differences in microbial community structure in psoriasis patients are potentially of pathophysiologic and diagnostic significance.


Psoriatic arthritis is a chronic inflammatory joint disease, seen in combination with the chronic inflammatory skin disease psoriasis and belonging to the family of spondylarthritides (SpA). A link is recognized between psoriatic arthritis and inflammatory bowel disease (IBD). Environmental factors seem to induce inflammatory disease in individuals with underlying genetic susceptibility. The microbiome is a subject of increasing interest in the etiology of these inflammatory immune-mediated diseases. The intestinal microbiome is able to affect extra-intestinal distant sites, including the joints, through immunomodulation. At this point, evidence regarding a relationship between the microbiome and psoriatic arthritis is scarce. However, we hypothesize that common immune-mediated inflammatory pathways seen in the “skin-joint-gut axis” in psoriatic arthritis are induced or at least mediated by the microbiome. Th17 has a crucial function in this mechanism. Further establishment of this connection may lead to novel therapeutic approaches for psoriatic arthritis.


The resident microbial community, harboured by humans in sites such as the skin and gastrointestinal tract, is enormous, representing a candidate environmental factor affecting susceptibility to complex diseases, where both genetic and environmental risk factors are important. The potential of microorganisms to influence the human immune system is considerable, given their ubiquity. The impact of the host–gene–microbe interaction on the maintenance of health and the development of disease has not yet been assessed robustly in chronic inflammatory conditions. PsA represents a model inflammatory disease to explore the role of the microbiome because skin involvement and overlap with IBD implicates both the skin and gastrointestinal tract as sources of microbial triggers for PsA. In parallel with genetic studies, characterization of the host microbiota may benefit our understanding of the microbial contribution to disease pathogenesis—knowledge that may eventually inform the development of novel therapeutics.

I think that this possible link between weather, microbes, and health issues like psoriasis and psoriatic arthritis should be investigated with further studies. There has been some research with the effects of temperature and barometric pressure on certain conditions like arthritis, but as far as I can tell from the things that I’ve read, no one knows exactly why. Microbes play a role in the immune system, so it doesn’t seem far-fetched that the microbial composition of the air has an effect on health.

I don’t believe that anyone has proposed this idea before. If you test it with experiments, please cite this blog post.

 Psoriasis Research  ,