Subject:  Viridian Note 00058: Grass Gas

Key concepts:  lawns, air pollution, organic compounds, 
crops, plant injury, biodiversity

Attention Conservation Notice:  Provokes possibly needless 
eco-anxiety, then exacerbates it with parodic sarcasm.

Source:  Article by Randolph E. Schmid, Associated Press.
Austin American-Statesman, April 3, 01999.

"Cutting the lawn may add toxins to the air, study says"

    "That sweet scent of a freshly mowed lawn may really 
be the smell of air pollution.

     "Scientists studying the sources of chemicals in the 
air have found that injured grass gives off volatile 
compounds.

      "'Wounding, cutting and drying of leaves and stems 
occur both naturally and by human activities.  Wound-
induced and drying-induced (...) compounds are expected to 
be significant in the atmosphere,' a team of researchers 
says in a study scheduled to appear in a future issue of 
the journal Geophysical Research Letters.

       "'In urban areas, lawn mowing by contribute to the 
total.... emissions and impact air quality,' the report 
says.  (...)

       "'It just  doesn't seem likely to me that the smell 
of newly mown grass is toxic,' said Ray Fall of the 
University of Colorado, a biochemist and one of the 
researchers. (...)

      "Yet, Fall said the team was surprised at the 
variety of chemicals released when crops were cut and 
during the drying process, including methanol, hexanal, 
acetaldehyde, acetone and butatone.  Some, such as 
acetone, can contribute to the formation of smog, the 
paper notes.

       "The scientists estimate that cutting crops adds 
about 1.6 million tons of acetone to the atmosphere 
annually, compared with estimated total natural emissions 
of 8 million to 13 million tons. (...)

      "'Cutting and drying organic material appears to be 
a significant global, and possibly regional, source of 
volatile organic compounds.  One that we think may not 
have been well accounted for before,' said Carlton Howard 
of the National Oceanic and Atmospheric Administration's 
Aeronomy Laboratory in Boulder, in a telephone interview."

(((bruces remarks:  to a darker, more suspicious frame of 
mind (my own), it seems *only too likely* that injured 
plants should give off "toxic" gases.  Plants are 
notorious for the fiendish ingenuity of their chemical 
defenses against herbivores.   Bad enough that we have to 
breathe this naturally!   Now, let us imagine the dire 
local effect of the mechanized lawnmower, which does not 
merely "cut" the lawn, but violently macerates all 
vascular plants into a reeking pulp!  This organic 
witches' brew combines with the vile greenhouse spew of 
the lawnmower's internal combustion engine, threatening 
the health of the homeowner and his family!   The obvious 
solution?  Abandon lawns!  Abandon that time-consuming, 
attention-hogging, watering, raking, fertilizing, and 
herbicidal spraying.   Embrace backyard biodiversity.  
Remember: if you can smell it, it's settling into your 
lungs.)))