Long-term exposure to air pollution may be linked to 15 percent of Covid-19 deaths globally, according to research published yesterday that highlights the health risks posed by greenhouse gas emissions. Previous research has showed how air pollution from exhaust fumes and factories takes two years off the life expectancy of every man, woman and child on Earth. In East Asia, which has some of the highest levels of harmful pollution on the planet, the authors found that 27 percent of Covid-19 deaths could be attributed to the health effects of poor air quality. In Europe the proportion was 19 percent, compared with 17 percent in North America.