I just read an article in the Toronto Star that makes me shake my head: Do trees spew 'contaminants'?. It's short, but I'll summarize anyhow: someone at Toronto's City Hall wrote a report stating that trees and vegetation are spewing contaminants, and someone else thought that sounded dumb, so the report is now getting a rewrite. Some other people asked for additional clarification, because apparently the report made no sense to anyone. A section on "air emissions" (I can only assume they are talking about the emissions of molecules and particles into the atmosphere, and not the actual emission of air) evidently
"focused on six air contaminants singled out by Environment Canada. They include carbon monoxide; compounds that cause acid rain; fine dust that causes respiratory ailments; and "volatile organic compounds" or VOCs. VOCs include a wide range of substances – some man-made chemicals such as benzene, and some natural substances. The smell of cut grass, for example, comes from VOCs."
Let's look up the word "contaminant", shall we?
con·tam·i·nant /kənˈtæmənənt/ Pronunciation Key - Show Spelled Pronunciatio [n. kuhn-tam-uh-nuhnt]
1. something that contaminates.
Okay, fine. So let's look up "contaminate".
con·tam·i·nate /v. kənˈtæməˌneɪt; n., adj. kənˈtæmənɪt, -ˌneɪt/ Pronunciation Key - Show Spelled Pronunciation[v. kuhn-tam-uh-neyt]
|1.||to make impure or unsuitable by contact or mixture with something unclean, bad, etc.: to contaminate a lake with sewage.|
|2.||to render harmful or unusable by adding radioactive material to: to contaminate a laboratory.|
The implication here is that a "contaminant" is something that doesn't belong or isn't natural. As far as I know, trees and vegetation are pretty naturally occurring things. So if a tree emits something into the atmosphere, that would also likely be natural, right? Exactly. Also, some natural things can burn naturally, emitting carbon monoxide and carbon dioxide (i.e.: forest fires started by lightning strikes). And volcanoes spew sulfur compounds, which become components of acid rain, also a very natural process.
Perhaps it is safe to conclude that many of the compounds in question can occur naturally in the atmosphere?
So... let's back up a second and STOP CALLING EVERYTHING A CONTAMINANT.
How about we just call them "chemical compounds"? Here's the thing - atmospheric scientists, and specifically atmospheric chemists know that there are naturally-occurring emissions and anthropogenic emissions of many of the same compounds or the same class of compounds. The key is to decipher what humans are doing versus what would happen in our absence. Are we offsetting the balance, or is our influence merely a drop in the bucket?
It's no wonder that the general public is so confused about the environment. Our policy makers can't even explain things properly in their own reports.