Formaldehyde is a volatile organic compound that is involved in the formation of photochemical smog in heavy metropolitan areas.
What is most likely a direct source of formaldehyde in the atmosphere?
combustion of fossil fuels
disintegration of road surfaces
evaporation from lumber products
aerosol particles from pressurized cans

i believe the correct answer from the choices listed above is the first option. the scientists need to look at the   validity of data, claims, hypotheses, and observations before  developing an argument. they base their arguments on facts that are present and they make sure they have proofs. 

explanation:

there’s no image attached but i can if you want: )

the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

i hope this

easy

explanation: