Our air and water has never been cleaner -- in Medieval Europe, for instance, water quality was so bad that even infants were given beer to drink, and in 1950s London, air quality was so poor that, in one single day alone, more than 4,000 people died from lung complications.
Actually, that's not quite true. While the average lifespan at the world level has been increasing, it's only because the poorest nations have improved personal hygiene, and realized the importance of clean water. It's not allowed to poo around water wells anymore.
But in developed and semi-developed countries, for the first time the lifespan of middle class has started shrinking. This is caused by many different poisons that are in small quantities added to almost everything we use. So that a single product can pass the test, but if you come in touch with a few of them, they add up and produce illnesses.
Those poisons are deliberately added to food (carcinogenic pesticides, carcinogenic preservatives, taste enhancers with known side-effects), and to drinking water, and to soft drinks, to clothing colors, to detergents, to plastic bottles, other plastic products (including toys for children), menstrual pads, cosmetics, frying pans, and whatnot. The number of contaminated products is constantly increasing.
We have examples of toxic teflon, which was sold until recently. Did we see similar campaign as against smoking? Nope. Even though teflon was actually more toxic.
Or E250 / E251, which is added to all processed meat products. You know when they say: "Statistics show that people who eat meat products are more prone to cancer"? Well, the key is in the words "meat products". Because meat alone is a lot safer, but processed meat products are impregnated with carcinogenic E250. Open your fridge, take any salami, packaged bacon, any packaged meat product, read the label, I guarantee there's either E250 or E251 in them. Known carcinogenic, causing colon cancer and other intestinal cancers.
Same goes for "safe" pesticides used to grow GMO plants, which are the basis of nowadays plant-based died. Be healthy, eat lots of vegetables, and still die of colon cancer.
Or say Byshpenol-A, which is a known gender-bender (estrogen emulator, feminizes male children) found in transparent plastic products, including bottles for feeding babies. The product is banned in Canada and Europe, but allowed in USA and many other countries. But just because it's banned doesn't mean there are no children toys impregnated with it. Inspections can only test a small number of products.
Same category of gender-benders are phataltes. They are banned in most of western countries, but still legal in less developed countries which make products that are sold worldwide. Inspections cannot properly test all the toys, so contaminated toys come in contact with their target population.
Or aspartame, which was banned in 1980'es, because it was toxic for brain and a possible cause of Alzheimer's. But 20 years later all those results were rejected and aspartame was approved. It causes brain damage, but that's exactly what the people who approved it want. Same is the case with most of artificial sweeteners. So no wonder they predict steep increase in Alzheimer's in the near future. How did they know? By using a crystal ball? Nope. They know what they are doing.
So, we're not improving anymore. Peak has been passed. Now we're declining. On purpose.