A study published this week has reported that methane emissions from Chinese coal mines have continued to rise, despite government regulations intended to cut the country’s pollution, potentially endangering those living near coal mines.

The study, led by Scot Miller of the department of environmental health and engineering at Johns Hopkins University and published in Nature, used Japan’s Greenhouse Gases Observing Satellite to measure the levels of methane in China’s air between 2010 and 2015.

The team found that methane emissions in 2015 were 50% higher than in 2000, an increase roughly equivalent to the total annual emissions of countries such as Russia and Brazil.

There has been a parallel increase in coal production in China, with output increasing two-and-a-half fold from 2000 to 2010, with China producing 3.4 billion tonnes of coal by the end of the period.

In 2006, the Chinese Government aimed to eliminate inefficiencies in the production process by setting targets for the utilisation of methane emitted from coal mines. The country aims to recover and reuse 20 billion cubic metres (bcm) of methane by 2020, instead of pumping it into the atmosphere, and announced that mining companies would not have to pay licensing fees or royalties on methane that is effectively utilised.

However, these initiatives have fallen short of expectations. In 2012, China recovered 3.5bcm of methane, which was well below the 2020 goal. Exemptions for miners have not addressed issues of excessive production of methane, and China’s over-reliance on coal, which accounted for 72% of the country’s electricity generation in 2015 – both of which pose more immediate threats to public health.

“Coal burning contributes 40% of China’s total, population-weighted PM2.5 [fine particulate matter] exposure and 366,000 premature deaths as of 2013,” the report reads.

While methane itself is relatively non-toxic in low concentrations, it can lead to suffocation and a loss of consciousness if inhaled in large enough volumes.

The report also claims that the methane utilisation scheme has backfired, as miners are willing to  bend laws to sidestep legal requirements. The law insists that all mines use gas with a methane concentration of greater than 30%. However, the report mentions “anecdotal evidence” presented to the Environmental Protection Agency that miners are illegally diluting waste gases from their operations until they have a low methane concentration, and simply venting these gases into the air, a practice which renders the methane unusable, and further adds to the levels of methane in the air.