Based on the search results, it is not possible to determine what is causing bad air quality today without additional information. However, the search results do provide information on the two biggest air quality problems in North Carolina, which are ground-level ozone and particle pollution PM2.5 and PM10. Both pollutants are caused chiefly by emissions from vehicles and from the coal-burning power stations that produce electricity. The air quality in North Carolina can be monitored through the Air Quality Index (AQI), which tells you how clean or polluted your outdoor air is and the associated health effects that may be of concern. The AQI is divided into six categories, each corresponding to a different level of health concern, and each category has a specific color. The primary causes of outdoor air pollution are solid and liquid particles called aerosols and gases from vehicle emissions, construction activities, factories, burning stubble and fossil fuels, and wildfires, among others.