Question

When Mario Molina and F. Sherwood Rowland first presented their findings about the threat of CFCs, the industrial chemists who developed CFCs scoffed at their warnings. They argued that CFCs were known to be very nonreactive. Would you categorize the reaction of these scientists as science or pseudoscience? Explain.What is Ozone?
Ozone is a gas made of oxygen atoms that occurs both in the Earth's upper atmosphere and at ground level. Ozone can be "good" or "bad" for your health and the environment depending on its location in the atmosphere. Ozone occurs in the troposphere, the atmospheric layer closest to the Earth’s surface. Here, ground-level, or "bad," ozone is an air pollutant that is harmful to breathe and it damages crops, trees, and other vegetation. It is a main ingredient of urban smog. Ozone also occurs in the stratosphere, the layer directly above the troposphere. Stratospheric, or "good," ozone protects life on Earth from the Sun's harmful ultraviolet (UV) rays.

Ozone is produced naturally in the stratosphere, but this area of “good” ozone is gradually being destroyed by manmade chemicals called ozone-depleting substances. These chemicals include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, and methyl chloroform. They are found in coolants, foaming agents, fire extinguishers, solvents, pesticides, and aerosol propellants. Once released into the air, ozone-depleting substances degrade very slowly. They often remain in the atmosphere for years, moving from the troposphere to the stratosphere. Once they enter into the stratosphere, they are broken down by the intensity of the Sun's UV rays and release chlorine and bromine molecules, which destroy the "good" ozone.

Holes in the ozone layer allow harmful ultraviolet rays to reach Earth’s plants and animals in excess. Too much ultraviolet light can result in eye damage like cataracts, immune system damage, skin cancer, DNA damage, and phytoplankton reduction in the oceans.

Ozone Depletion History
In cold areas such as Antarctica, there are stratospheric cloud ice particles that are not present at warmer latitudes. Reactions occur on the surface of the ice particles that accelerate the ozone destruction caused by stratospheric chlorine. Temperatures hover around or below negative 80 degrees celsius for much of the winter and extremely low Antarctic temperatures cause cloud formation in the relatively "dry" atmosphere. These Polar Stratospheric Clouds (P S C's) are composed of ice crystals that provide the surface for a multitude of reactions, many of which speed the degradation of ozone molecules.
Ozone depletion history began in the late 1950s with ground-based ozone measurements from Antarctica taken by international collaboration efforts. In 1974, Mario Molina and Frank Sherwood Rowland published an article in Nature on the developing threat to the ozone layer from the use of chlorofluorocarbons (CFCs), gaseous compounds used as refrigerants, aerosol propellants, solvents, and in foam. The study estimated that the ozone layer would be depleted by CFCs by about seven percent within 60 years. Based on such studies, the US banned CFCs in aerosol sprays in 1978. Also in 1978, the first comprehensive global measurements began with the Nimbus-7 satellite, which carried the total ozone mapping spectrometer (TOMS). Testing continued through the 1990s.

Mario Molina (left) and Frank Sherwood Rowland (right).
Photos by Janwikifoto and Markus Possels
Mario Molina (left) and Frank Sherwood Rowland (right) received the 1995 Nobel Prize in Chemistry on their work on ozone depletion.

Answer 1

Short answer: it depends — healthy skepticism is part of science, but the kind of dismissive scoffing you describe crosses into unscientific (and, when done to avoid evidence, pseudoscientific) behavior.

Why: science requires making testable claims, proposing mechanisms, and checking them against data. Molina and Rowland did that: they published a detailed chemical mechanism showing how CFCs, though inert at the surface, could be photodissociated in the stratosphere to release chlorine atoms that catalytically destroy ozone. They made quantitative predictions and suggested observations and experiments to test them. That is proper scientific practice.

By contrast, simply asserting “CFCs are nonreactive, so they can’t harm ozone,” and refusing to engage with the proposed mechanism or with new measurements is not good science. Initial skepticism about a surprising claim is appropriate, but skepticism becomes unscientific or pseudoscientific when it rests on argument-from-ignorance, appeals to authority, selective use of facts, or refusal to perform or accept relevant tests. In the Molina–Rowland case, subsequent laboratory measurements, field observations and satellite data (including discovery of the Antarctic ozone hole and TOMS measurements) confirmed their mechanism and predictions; industry resistance that ignored or tried to dismiss such evidence amounted to denialism rather than science.

What is ozone? (brief)
- Ozone is the triatomic form of oxygen, O3.
- Stratospheric (“good”) ozone, concentrated in the ozone layer, absorbs harmful ultraviolet (UV) radiation from the Sun and protects life on Earth.
- Tropospheric/ground-level (“bad”) ozone is a pollutant that damages lungs, crops, and vegetation and contributes to smog.
- Certain manmade chemicals (CFCs, halons, methyl bromide, etc.) are long-lived in the lower atmosphere, drift into the stratosphere, and are photodissociated by UV light, releasing chlorine or bromine atoms that catalytically destroy ozone molecules.
- Polar Stratospheric Clouds (PSCs) in very cold regions such as Antarctica facilitate reactions that greatly accelerate ozone loss there, producing the seasonal Antarctic ozone hole.
- Ozone depletion raises UV exposure and increases risks such as skin cancer, cataracts, immune damage, and ecological harm.