No! Let's estimate the fluence of red and NIR light one might get from the sun on an average summer day under the shade of a tree...
1. Sunlight Spectrum Intensity:
Sunlight is approximately 1000 W/m^2 in direct sunlight. When considering the red to NIR range (600-900nm), about 43% of the solar spectrum falls into this range. So, the intensity in this range is approximately: 0.43 x 1000 W/m^2 = 430 W/m^2
2. Shade Reduction:
Being in the shade can reduce sunlight intensity by around 50-90%, depending on the shade's type and density. Let's take an average value of 70% reduction. Intensity in the shade = 0.3 x 430 W/m^2 = 129 W/m^2
3. Conversion to Fluence (Total Dose):
Fluence (J/cm^2) is power (W/cm^2) multiplied by time (seconds). Let's consider
exposure over a day (let's say 6 hours of variable sunlight in shade). This would be 6 x 60 x 60 seconds = 21,600 seconds.
First, convert the intensity from W/m^2 to W/cm^2:
129 W/m^2 = 0.0129 W/cm^2
Then, compute the fluence:
Fluence = 0.0129 W/cm^2 x 21,600 s = 278.88 J/cm^2
So, in the shade on an average summer day, one could be exposed to a total
fluence of near 300 J/cm^2 in the red & near infrared range from the sun.
We find the total exposure seems to be more important in
many processes, so we us multi-watt red/nir light in our device to offer quick effective treatments.
High Fluence Supporting Research: