Definition

Percent of days in which the average concentration of fine particulate matter exceeds the regulatory standard at a monitoring point. Fine particulate matter is defined as particles that are 2.5 microns in diameter or less (PM2.5).

Numerator

Number of days in a year in which the PM2.5 concentration at a monitor exceeded the National Ambient Air Quality Standard of 35 micrograms per cubic meter, averaged over 24 hours.

Denominator

For percent of days: number of days in a year

Why Is This Important?

Particulate matter (PM) is a mixture of solid particles such as dust, ash, smoke and droplets in the air. PM can be emitted directly from a source (e.g., smoke stacks, tail pipes or construction sites) or can form in the atmosphere from chemicals emitted by power plants, industries and cars. Fine particles -- 2.5 microns in diameter or less (PM2.5) -- are of greatest health concern since they can be breathed deep into the respiratory tract. Exposure to these particles can lead to asthma attacks, coughing, shortness of breath, bronchitis, lung cancer, and premature death.

How Are We Doing?

New Jersey's Particulate Monitoring Network consists of 15 PM2.5 monitoring sites, 3 PM10 monitoring sites, and 5 sites where black carbon is monitored. Air quality in New Jersey has been improving. New Jersey's air monitoring program evaluates hourly air quality readings using the Air Quality Index (AQI). The AQI uses five of the six pollutants for which there are national health-based standards (ground-level ozone, particulates, carbon monoxide, nitrogen dioxide, sulfur dioxide) and compares the composite pollutant levels to the federal standards in order to assign an air quality rating such as "good" or "unhealthy". In 2020, the annual mean concentrations of PM2.5 ranged from 5.48 ug/m3 at the Morris County monitoring site to 9.55 ug/m3 at the Bergen County monitoring site. No sites were in violation of either the newer (2013) annual standard of 12.0 ug/m3 or the older 15.0 ug/m3 standard. The 24-hour standard of 35 ug/m3 was established in 2006.

What Is Being Done?

New Jersey has put added emphasis on controlling emissions from diesel engines due to the severe adverse health effects associated with exposure to the components of diesel particles. Success story: Recommendations for Reducing Smog Throughout NJ and Beyond [http://www.nj.gov/health/ceohs/documents/epht/tra_action/reducing_smog_in_nj.pdf] Success story: Air Quality and Asthma in NJ Children [http://www.nj.gov/health/ceohs/documents/epht/tra_action/helping_children_breathe_easier.pdf] Success story: Collaborating to Diminish Smog and Improve Health in NJ [http://www.nj.gov/health/ceohs/documents/epht/tra_action/clean_air_nj.pdf]