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San Diego Kawasaki Disease & Relative Humidity

March 25, 2016


Kawasaki Disease vs. Relative Humidity San Diego r1

Orange Data is Kawasaki Disease Cases Per Month, Blue is Avg Monthly Afternoon (4 PM) humidity.  Electrostatic potentials increase with decreasing humidity. Desert Winds begin around November in San Diego. Sand creates additional electrostatic charge in the atmosphere.

San Diego Kawasaki Disease Rate Table

In this data, the Daily number is the average of humidity readings taken every three hours throughout the day. Morning percentages are for 7 am and Afternoon measures are for 4 pm local standard time.[1]

Although the seasonality of KD in many regions has been recognized for over two decades, the first systematic study of a KD/climate association was conducted at UCSD. During the five-year study period (1994-1998), a total of 169 San Diego residents were diagnosed and treated for KD in San Diego County. Date of admission was used to analyze the mean distribution of patients by month. Despite the temperate climate and lack of extreme seasonal temperature variation in San Diego County, a peak in KD cases was consistently noted in the late winter/early spring. This coincided with the months of lowest temperatures and greatest precipitation. Because of the substantial variation from year to year in temperature and precipitation, we analyzed the association between the number of KD patient admissions per month and mean monthly temperature and precipitation over the study period. KD incidence was inversely associated with mean monthly temperature (r=-0.47, p<0.001), and positively associated with mean monthly precipitation (r=0.52, p<0.001) during the 60-month period. [2]

In October 2007, the winds fueled major wild fires and house burnings in Escondido, Malibu, Rainbow, San Marcos, Carlsbad, Rancho Bernardo, Poway, Ramona, and in the major cities of San Bernardino, San Diego and Los Angeles. The Santa Ana winds were also a factor in the November 2008 California wildfires. [3]

Typical relative humidity values in Santa Ana wind events are in the 5% to 15% range which is extremely dry. In some cases it can drop below 5%. This results in greater static electricity for those shuffling across the carpet or getting in and out of a car with carpet. Hence small static electricity shocks one common when touching metal during Santa Ana winds. [4]


When the Santa Ana winds blow in Southern California in Fall, the humidity drops significantly and the electrostatic charge from dust in the atmosphere increases.

A recent study [5] finds that the initial saltation of sand particles induces a static electric field by friction. Saltating sand acquires a negative charge relative to the ground which in turn loosens more sand particles which then begin saltating. This process has been found to double the number of particles predicted by previous theories.[3]

San Diego Desert Winds

Association of Kawasaki disease with tropospheric winds in Central Chile: Is wind-borne desert dust a risk factor?

  • a Departamento de Ingeniería Química y Bioprocesos, Pontificia Universidad Católica de Chile, Santiago, Chile
  • b Centro de Desarrollo Urbano Sustentable (CEDEUS), Chile
  • c Unidad de Inmunología, Alergia y Reumatología Pediátrica, División de Pediatría, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
  • d Instituto Milenio de Inmunología e Inmunoterapia, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
  • A statistical association of meteorological variables with Kawasaki disease found for a large city in the Southern hemisphere


  • Climate-scale (ENSO) dynamics are associated with Kawasaki disease, and may confound seasonality on a global scale.


  • Results suggest that windborne desert dust may include a causative agent. [I think the causative agent is electrostaic charge]


  • Results are consistent with studies conducted in the Northern hemisphere.


It has been found that Kawasaki disease (KD) cases diagnosed in Japan, Hawaii and San Diego, USA increase when tropospheric wind patterns arrive from central Asia, suggesting a common, wind-borne causal agent.


Neutral Dust Particles can become charged in the atmosphere. Source:


My Conclusion:

When wind patterns originate over dry land and deserts vs. humid oceans and also during winter months when the air is colder and the relative humidity drops, static electrical potentials will increase in the atmosphere and on land, especially on man-made non-conductive synthetic materials.  Sand and fine particulate in the atmosphere picked up over the desert can create excess static electrical charge in the atmosphere, including sand in contact with water vapor.  The stronger static electric field potentials on humans and surrounding insulators (plastics, carpet, etc) trigger more potential for disease due to capacitance and electrical charge/discharge cycles.  Kawasaki disease may be caused from the sudden/repeated buildup and electrical discharge of these electric fields, which can be higher during low humidity months and when electrical charges in the atmosphere increase. Kids are more at risk because they crawl on carpets and are very active and generate lots of static and their volume/surface area is lower than adults and Q/A can be higher.


  • Humidify well during dry months, KD incident rate drops steeply above RHs of 60%
  • Minimize sources that create electrostatic charge imbalance between child and Earth/atmosphere: ie. crawling on carpets, riding in shopping carts that create static, sliding down plastic playground slides (skin contact with plastic),  sliding on artificial/rubber turf, playing on rubber mats with bare feet.  Static imbalance potential  will be worse as it gets colder and humidity drops and when winds increase static electrical charges in the atmosphere.
  • Wear cotton clothes, not synthetic poly clothing that builds lots of static charge.  Synthetics can strip electrons from you through triboelectric effects and also build/maintain electric charge on their surface.
  • Ground everything and do not let excess voltage (electrostatic charge) build up in the first place. Electrostatic discharge shoes for children may help
  • Everybody move to the tropics…

Data Sources:


From → Biology, Geophysics

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