Outdoor air pollution, in the most extreme cases, can be immediately identified even without any special training. It casts a haze over cities, collects on streets and buildings, and provides dramatic fodder for the news. But while high drama is often a prerequisite for news about air quality to be reported, the real story is the health impacts that occur even when the air isn't thick enough to see.

According to the EPA, Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations. Most pollutants affecting indoor air quality come from sources inside buildings, although some originate outdoors. Typical pollutants of concern include combustion products such as carbon monoxide, particulate matter, and environmental tobacco smoke; substances of natural origin such as radon; biological agents such as molds; pesticides; lead; asbestos; ozone (from some air cleaners); and various volatile organic compounds from a variety of products and materials

This is even more striking when the health effects attributed to outdoor fine particulate matter (PM2.5) rank among the risk factors with the highest health impacts in the world, annually accounting for over 3.2 million premature deaths. In October 2013, the World Health Organization announced they are considering particulate matter, a major component of indoor and outdoor air pollution, as a Group 1 carcinogen along with tobacco smoke and asbestos.

U.S. EPA Standards and Test Methods

National Ambient Air Quality Standards (NAAQS)

Section 109 of the Clean Air Act directs the Environmental Protection Agency (EPA) to establish National Ambient Air Quality Standards (NAAQS) requisite to protect public health with an adequate margin of safety (primary standard) and for the protection of public welfare (secondary standard). Section 109(d)(1) of the CAA requires EPA to complete a thorough review of the NAAQS at 5-year intervals and promulgate new standards when appropriate.

Complete details of the standards, measurement principles, and data interpreation, can be found in Title 40 of the Code of Federal Regulations Part 50

Summary of the NAAQS Criteria Pollutants

EPA Test Methods

EPA approved instruments are designated as either a Federal Reference Method (FRM) or Federal Equivalent Methods (FEM). For PM testing, the FRM is typically a manual test method whereby PM is collected on a filter for 24-hours (daily). The mass is determined by gravimetric analysis (weighing the filter before and after sample collection) and the sample volume is calculated based on the air flow rate multiplied by the sample duration. Then the mass concentration (typically in microgram per cubic meter, ug/m3) is calculated as the mass collected divided by the sample volume.

The FEMs for PM utilize detectors capable of real time reporting. The air sample volume is usually determined by air flow rate and duration akin to the FRM. However, the mass may be measured by the beta ray attenuation method (BAM) or tapered element oscillation method (TEOM).

The complete list of approved instruments for NAAQS evaluating is provided on the EPA Ambient Monitoring Technology Information Center (AMTIC) web site

Real Time Data

EPA and its State and Tribal partners publish near real-time air quality data (typically hourly updates) as well air quality forecasts on the AirNow web site.

The AirNow site also contains, links to Visibility Cameras, which are yet another way to evaluate particulate pollution.

Historical Data

Historical air quality test results are freely available through EPA AirData

EPA & Citizen Science Next Generation of Monitors

EPA has also been involved with Next Generation Air Measuring and is currenlty offering its Citizen Science Toolbox Resources online: - Air Sensor Guidebook; - Air Sensor Technology: State of the Science Presentation; - Mobile Sensors and Applications for Air Pollutants; and - Sensor Evaluation Report.

Other Resources for Air Quality Standards

The U.S. Center for Disease Control (CDC) and its National Institute for Occupational Safety and Health (NIOSH) also offer a wealth of guidance. In partiuclar, the NIOSH Manual of Analytical Methods is a collection of procedures for sampling and analysis of contaminants including workplace air.

The Agency for Toxic Substances and Disease Registry (ATSDR), based in Atlanta, Georgia, is a federal public health agency of the U.S. Department of Health and Human Services. Their Toxicological Profiles, is particularly useful for when a polutant can be identified by compound or element.

Particle Sensing Project

Public Lab has initiated a Particle Sensing Project focused primarily on Silica. This project overlaps with and includes the DustDuino and is coordinated on the Air-Quality Google Group.

Welcome to the PLOTS Air Quality Google Group

This is the link to the Public Laboratory mailing list devoted to air quality research and discussion. Several projects use this list, including hydrogen sulfide sensing near fracking sites, "DustDuino" by Matt Schroyer and Willie Shubert, the "balloon board" modification to Air Quality Egg that serves as an air column monitor, and others. In the past, this list served the Cypress Hills Air Quality (CHAQ) initiative. Now it hosts a wide variety of projects, so jump in!

Cypress Hills Air Quality (CHAQ) Initiative

This 8 week Air Quality Class was created for the Cypress Hills Air Quality (CHAQ) Initiative, with support from the United States Environmental Protection Agency's program "Citizen Science: Community Involvement Today and in the Future". This project was a collaboration with the Cypress Hills Local Development Corporation. Joe Saavedra and Liz Barry are the Public Laboratory facilitators. Georgia Bullen, Yael, and Jason Lipshin are involved from MIT.

Roomba Indoor Air Quality Mapping

This tool is being developed to experiment with mapping indoor air quality. A Roomba--the room cleaning vacuum--is programmed to travel all around a room once it is left to roam. Therefore, it is an ideal tool to assess the quality of air through out a room.

Air Column Monitor

The air column monitor is currently in early phases of development. The April 2012 EcoHackII at Parsons in NYC brought together a group of developers, "scientists", data visualizers and activists to work on the initial design. This tool is being developed as a partnership between Public Lab and the AirQualityEgg/Sensemakers community.

DustDuino

DustDuino can help individuals with limited resources monitor PM10 and PM2.5 concentrations, indoors or outdoors. It uses Shinyei PPD42NS, a $15USD optical sensor that uses an LED and a lens to determine the concentration of dust in a partially closed chamber that draws in air from its surroundings. The sensor data is received by an Arduino development board and transmitted to Xively. Prototypes of DustDuino have been successfully built and used in various indoor and outdoor locations.