Air pollution in Costa Rica’s capital San Jose has exceeded the standard level set by the World Health Organization (WHO) and the U.S. Environmental Protection Agency, a study said Tuesday.

The concentration of atmospheric particulate matter, or PM2.5, in the air reaches as high as 31 micrograms per cubic meter (31mcg/m3), while international norms say there should be no more than 10mcg/m3, according to the study compiled by Costa Rica’s Autonomous National University.

It also warned of an increase in air pollution from nitrogen dioxide (NO2), a toxic gas.

“NO2 levels continue to increase at commercial and industrial sites in the metropolitan area, though this year’s rate of increase was slightly lower compared to the previous period,” the study said.

The report also showed that acid rain is getting worse, with the number of times per year that pH readings fall below 5.6 rising to a rate of 16.5 percent annually between 2007 and 2011.

Particulate matter is generated by vehicle emissions and industrial activities. Breathing in the particles in high concentration can cause respiratory diseases and possibly lung damage, experts say.

Source: Nacion.com