Meanwhile, new environmental laws have meant that emissions from electrical plants, a major polluter, have been decreasing since 2001.

Emission inventories can be compared with air pollutant levels in an area to determine if increased emissions decreases the air quality.

They said the agency had conducted a study on the situation and had found that noxious emissions would decrease through the year 2000.

Between 1990 and 2009 Sweden's emissions decreased slightly, but they increased again in 2010.

Over the same period, territorial-based emissions decreased 1.2% each year.

Moreover, its long half-life means that this emission decreases very slowly with time.

The emission of ionones was also higher during the day; however, emissions decreased at a lower rate than the transcript levels.

Meanwhile, emissions of carbon dioxide from human activities may be decreasing; he said they shrank slightly in 1998 and 1999, even as the global economy grew.

Total acidifying emissions have decreased very rapidly since 1990, but NOx still remains a problem.

In the period 1990-2006, emissions decreased by 33%.