> a Monash University study has found that only 0.18% of the global land area and 0.001% of the global population are exposed to levels of PM2.5 - the world’s leading environmental health risk factor – below levels of safety recommended by Word Health Organization (WHO).<p>I can't quite suss out the details, but it seems like they're saying that only 0.18% of global land area had levels of PM2.5 lower than the WHO's recommended levels _every day_.<p>Most of the study seems to be looking at how those levels vary by day, but the big claim doesn't reference % of days at all, which is odd. Their bullet points are a little confusing as well:<p>> Despite a slight decrease in high PM2.5 exposed days globally, by 2019 more than 70% of days still had PM2.5 concentrations higher than 15 μg/m³.<p>Where, though? They measured different geographic areas, but this has no geographic information. That leads me to believe that the claim is that on 70% of days there was at least one geographic location with PM2.5 concentrations higher than 15 μg/m³.<p>> In southern Asia and eastern Asia, more than 90% of days had daily PM2.5 concentrations higher than 15 μg/m³.<p>This is much clearer but suggests that my interpretation of the last bullet was wrong... maybe that one meant a global average?<p>I dunno, maybe I should read this again after some more coffee, but it seems to be written in a confusing way that goes back and forth from global averages to local averages to number of days above a threshold to annual averages.