Air pollution impact on plant growth - how to simulate?

[deleted-305577]

Experiment is to test the impact of air pollution on plant growth starting from seed, specifically the degree of light a plant receives. Would like to conduct indoors with plant lights and plants inside several different boxes, but am having problems determining the appropriate way to simulate what air pollution does to sunlight received by a plant. Had considered film tinting over the lighting, or cloth of different thicknesses, but am having difficulties determining what level of tinting is similar to a smoggy day in L.A. or Beijing, etc. Any ideas on how to simulate the smog impact on sunlight in a way that may mimic real world conditions using lighting only? Thank you very much for any thoughts you might have!

[bfinio]

Hi scienceparent7,

I tried a google search for "how much sunlight does smog block" and one of the first hits was this article, which cites smog over the Indian Ocean blocking out "10-15% of the Sun's rays":

https://www.newscientist.com/article/dn ... t-the-sun/

However, I also found this article which discusses the "sunburn on a cloudy day" effect, and that ultraviolet light can get through clouds (not sure if the same is true for smog) better than visible light:

http://www.americanscientist.org/issues ... cloudy-day

So, not sure what type of plant lights you were planning on using - but if they emit UV light, you might need to take that into account.

I would try some more Googling using different combinations of similar words (like "how much sunlight does smog filter", or "global dimming" which is mentioned in this Wikipedia article: https://en.wikipedia.org/wiki/Global_dimming) to try and find more sources than that single 10-15% number from that article. It might take a bit of detective work to weed out irrelevant results - when I tried "how much light does smog block", for some reason I got a bunch of pages about motorcycles (which apparently have something called a "smog plate").

As for measurements, you can buy a "lux meter," which measures light levels, pretty cheaply on Amazon, but you can also just download a free lux meter app for most newer smartphones. That would allow you to measure the brightness of a lamp and then decide what filtering materials to use to reduce the brightness by a certain amount. The caveat is that those meters/apps probably only work for visible light and not UV.

[deleted-305577]

Thank you very much for these ideas! We are using LED lighting and have learned a great deal about lumens and light temperature. We were trying to approximate "normal" sunlight as much as possible, but your idea to use other studies in a reductive way makes sense - the light we are using as a constant will be the "sun" (as close as we can get) and using the Lux meter we will reduce that by 10% or 15% by whatever means necessary (tinting, cloth, paper) depending on what we find. We are still thinking about UV - this does complicate things a bit but if all things are the same it may not matter. This is a great forum and really helpful! Keep up the great work!

[bfinio]

Glad that you found the forum helpful!

One more note - I'm a mechanical engineer so plants are not my area of expertise at all. I would do some research to confirm what spectrum of light plants absorb. I'm not sure if it varies from plant to plant. The first google result for "LED grow light" returned this page which has a graphic about chlorophyll and the colors absorbed:

https://www.earthled.com/collections/ea ... row-lights

So, be careful with which LED lights you use. I know you can get "daylight" bulbs but they probably don't have the same spectrum as "grow lights" specifically designed for plants. You wouldn't want to have your plants mysteriously die because they are not getting the right type of light.