I strongly suspect this gas stove study was done, in support of future political plans to move away from hydrocarbon based fuels in this country. California already has plans to ban natural gas stoves in all future new home construction. And this type study, though having many flaws, it fits politically with encouraging the public to adapt to the future strategies. And you should do it now for the sake of your children. Not even subtle and certainly sneaky and borderline unethical.
Reminds me of the huge political strategy we faced in 1970's and 80's. To help the environment and save our forests, everyone was encouraged to switch to plastic bags, plastic plates, plastic straws and reduce use of paper products whenever possible. Scientific studies by universities were released, that clearly showed, for every 10 million people that switched from paper to plastic, we could save 100,000 acres of forests in this country. Plastic was touted in all the studies, as the best and safest for the environment. Grocery stores were required by law to do way with paper bags and supply plastic bags only. And 25 years later, we all know how this strategy worked out. We nearly destroyed the world with millions of tons of plastics.