Developing a smartphone software package for predicting atmospheric pollutant concentrations at mobile locations

Air quality has a direct impact on pulmonary and cardiovascular health. Short term exposures to high concentrations of fine particulate matter (PM2.5), coarse particulate matter (PM10) and ozone are associated with increased risk of asthma attacks [1]. Long term exposure to lower levels of these pollutants are associated with increased risk of developing asthma [2] and decreased respiratory function [3]. It is currently estimated that 147 million Americans (41%) are exposed to elevated levels of air pollutants [4]. The United States Environmental Protection Agency (U.S. EPA) has identified ground-level ozone and PM2.5 as the two air pollutants that pose the greatest threat to human health [5], yet the level of concern among the general public regarding these pollutants varies widely and is largely dependent upon a person's perception of risk [6]. Efforts to communicate air quality using terminology such as “PM10” and μg/m3” are perceived as too complex for the general public [7], and air quality information that is reported at national and regional levels is not always practical for an individual [8]. Smartphones have great potential to contribute to communicating personalized information about health risks including air pollution [5, 9]. There are an estimated one billion active smartphone users worldwide [10]. For a smartphone to facilitate communication and understanding of the health risks posed from air pollution the software (app) must 1) provide pollutant information that is representative of actual pollutant conditions at the person's current location and 2) be perceived as useful and easy to use by the general public [11]. The U.S. EPA released an “AirNow” app which identifies the user's current location and lists measured air pollutant concentrations as the air quality index (AQI),at the closest U.S. EPA air monitoring station. The AQI combines the concentration of ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide into a single index that describes the local air quality using a scale from 1-500 with 6 color coded categories ranging from good (green, index value 1-50) to hazardous (maroon, index value 300-500) [5]. This app provides useful personal air quality information but has limited utility for users who are not located near an air monitoring station or are uncertain of the nearest air monitoring station location. AirNow is also limited to the most recent measurements of pollutant information and requires focused attention from the user, making it difficult to evaluate personal air quality conditions over time and/or during health events of interest such as an asthma attack. To address these limitations, we developed the ParME (particulate matter estimator), app. This is a new software package that utilizes spatial pollutant distribution models to predict air pollutant levels at any smartphone location and send predicted pollutant level information to the smartphone device. The software accesses all the predicted pollutant information associated with the current location of the user's smartphone and lets users set personalized warning levels for predicted atmospheric pollutants. The software is consistent with the color warning categories employed by the the EPA AQI and presents this information in well-known formats such as Google maps and simple graphs. The complex sampling information such as predicted levels and latitude/longitude values is hidden from the user until that information is requested. ParME further minimizes user effort by collecting predicted air quality data and checking for warning levels while running in the background, which further empowers the user to collect personal information about air quality at their location.