Assertion: formaldehyde | /r/AtLocation | the atmosphere
Facets:
value: naturally
type: MANNER
Source sentences:
text: Formaldehyde occurs naturally in the atmosphere at a concentration of about 10 parts per billion (0.000 001%) partly as a by-product of plant and animal metabolism, and partly as a product of the reaction of sunlight with methane (CH 4 ), a much more abundant component of the air.