PM2.5: When it's unsafe to breathe

Concerning the problem of fine particulate matter smaller than 2.5 microns (PM2.5), Bangkok was recently ranked among the worst cities for air quality according to Swiss-based IQAir. The number of patients with pollution-associated diseases has been reported to be high each year, with people risking their health just by breathing outside their homes. 

Some protocols have been implemented by government agencies to address the issue. However, this still leaves the question: When will the situation in Bangkok, which translates to the 'city of angels' improve?