Interestingly, today's NASA Earth Observatory image of the day is "Smog Smothers Solar Energy in China" https://earthobservatory.nasa.gov/IOTD/view.php?id=92054

A quote from the article: "The researchers found that in the most polluted areas, available solar energy decreased as much as 35 percent, or 1.5 kilowatt-hours per square meter per day. That is enough energy to power a vacuum cleaner for one hour, wash twelve pounds of laundry, or run a laptop for five to 10 hours."