Validating novel air pollution sensors to improve exposure estimates for epidemiological analyses and citizen science.

Low cost, personal air pollution sensors may reduce exposure measurement errors in epidemiological investigations and contribute to citizen science initiatives. Here we assess the validity of a low cost personal air pollution sensor. Study participants were drawn from two ongoing epidemiological projects in Barcelona, Spain. Participants repeatedly wore the pollution sensor - which measured carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO2). We also compared personal sensor measurements to those from more expensive instruments. Our personal sensors had moderate to high correlations with government monitors with averaging times of 1-h and 30-min epochs (r ~ 0.38-0.8) for NO and CO, but had low to moderate correlations with NO2 (~0.04-0.67). Correlations between the personal sensors and more expensive research instruments were higher than with the government monitors. The sensors were able to detect high and low air pollution levels in agreement with expectations (e.g., high levels on or near busy roadways and lower levels in background residential areas and parks). Our findings suggest that the low cost, personal sensors have potential to reduce exposure measurement error in epidemiological studies and provide valid data for citizen science studies.

Locations of joint physical activity in parent-child pairs based on accelerometer and GPS monitoring.

BACKGROUND: Parental factors may play an important role in influencing children's physical activity levels. PURPOSE: This cross-sectional study sought to describe the locations of joint physical activity among parents and children. METHODS: Parent-child pairs (N = 291) wore an Actigraph GT2M accelerometer and GlobalSat BT-335 global positioning systems (GPS) device over the same 7-day period. Children were ages 8-14 years. Joint behavior was defined by a linear separation distance of less than 50 m between parent and child. Land use classifications were assigned to GPS datapoints. RESULTS: Joint physical activity was spread across residential locations (35 %), and commercial venues (24 %), and open spaces/parks (20 %). Obese children and parents performed less joint physical activity in open spaces/parks than under/normal weight children and parents (ps < 0.01). CONCLUSIONS: Understanding where joint parent-child physical activity naturally occurs may inform location-based interventions to promote these behaviors.

Neighborhood park use by children: use of accelerometry and global positioning systems.

BACKGROUND: Although having a greater number of neighborhood parks may be associated with greater overall physical activity in children, information is lacking about the extent to which children actually use parks for physical activity. PURPOSE: This study combined accelerometer, GPS, GIS, and self-report methods to examine neighborhood park availability, perceived proximity, and use for physical activity in children. METHODS: Low- to middle-income children (aged 8-14 years) (n=135) from suburban communities in Southern California wore an Actigraph accelerometer and GlobalSat BT-335 GPS device across 7 days to measure physical activity and park use, respectively. ArcGIS identified parks within a 500-m residential buffer of children's homes. Parents reported perceptions of neighborhood park proximity through the Neighborhood Environment Walkability Survey (NEWS). Data were collected from March 2009 to December 2010, and analyzed in 2013. RESULTS: Fifty-four percent of families lived within 500 m of a park. Of these children, GPS data indicated that 16% used it more than 15 minutes and an additional 11% of children used it between 5 and 15 minutes during the 7-day study period. The odds of extended park use (>15 minutes) increased fourfold when the distance between home and the nearest neighborhood park decreased by 100 m. Additionally, the odds of any park use (>5 minutes) doubled when moving from the 25th to the 75th percentile for park greenness/vegetation density. CONCLUSIONS: Although children's use of neighborhood parks was generally low, it increased substantially when parks were closer to children's homes and had greater vegetation density.

Smart growth community design and physical activity in children.

BACKGROUND: Physical inactivity is a leading cause of death and disease globally. Research suggests physical inactivity might be linked to community designs that discourage active living. A "smart growth" community contains features likely to promote active living (walkability, green space, mixed land use), but objective evidence on the potential benefits of smart growth communities is limited. PURPOSE: To assess whether living in a smart growth community was associated with increased neighborhood-centered leisure-time physical activity in children aged 8-14 years, compared to residing in a conventional community (i.e., one not designed according to smart growth principles). METHODS: Participants were recruited from a smart growth community, "The Preserve," located in Chino, California, and eight conventional communities within a 30-minute drive of The Preserve. The analytic sample included 147 children. During 2009-2010, each child carried an accelerometer and a GPS for 7 days to ascertain physical activity and location information. Negative binomial models were used to assess the association between residence in the smart growth community and physical activity. Analyses were conducted in 2012. RESULTS: Smart growth community residence was associated with a 46% increase in the proportion of neighborhood moderate-to-vigorous physical activity (MVPA) as compared to conventional community residence. This analysis included neighborhood activity data collected during the school season and outside of school hours and home. Counterfactual simulations with model parameters suggested that smart growth community residence could add 10 minutes per day of neighborhood MVPA. CONCLUSIONS: Living in a smart growth community may increase local physical activity in children as compared to residence in conventionally designed communities.

A study of community design, greenness, and physical activity in children using satellite, GPS and accelerometer data.

This study examined relationships between greenness exposure and free-living physical activity behavior of children in smart growth and conventionally designed communities. Normalized Difference Vegetation Index (NDVI) was used to quantify children's (n=208) greenness exposure at 30-s epoch accelerometer and GPS data points. A generalized linear mixed model with a kernel density smoothing term for addressing spatial autocorrelation was fit to analyze residential neighborhood activity data. Excluding activity at home and during school-hours, an epoch-level analysis found momentary greenness exposure was positively associated with the likelihood of contemporaneous moderate-to-vigorous physical activity (MVPA). This association was stronger for smart growth residents who experienced a 39% increase in odds of MVPA for a 10th to 90th percentile increase in exposure to greenness (OR=1.39, 95% CI 1.36-1.44). An individual-level analysis found children who experienced >20 min of daily exposure to greener spaces (>90th percentile) engaged in nearly 5 times the daily rate of MVPA of children with nearly zero daily exposure to greener spaces (95% CI 3.09-7.20).

Joint physical activity and sedentary behavior in parent-child pairs.

PURPOSE: The research examined joint physical activity and sedentary behavior among 291 parent-child pairs who both wore an accelerometer and Global Positioning System (GPS) device during the same 7-d period. METHODS: Children were 52.2% female, 8-14 yr, and 43.0% Hispanic. Parents were 87.6% female. An ActiGraph GT2M accelerometer and GlobalSat BT-335 GPS device collected activity and global positioning data, respectively. Linear distance between the parent and child for each 30-s epoch was calculated using geographic coordinates from the GPS. Joint behavior was defined as a separation distance less than 50 m between parents and children. RESULTS: On average, during nonschool waking hours, parents and children spent 2.4 ± 4.1 min·d (mean ± SD) performing moderate-to-vigorous physical activity (MVPA) together and 92.9 ± 40.1 min·d in sedentary behavior together. Children engaged in an average of 10 min·d of MVPA during nonschool waking hours when their parent was nearby but not engaging in MVPA. During this same period, parents engaged in 4.6 min·d of MVPA when their child was nearby but not engaging in MVPA. Household income level and the child's age were negatively associated with joint MVPA. Girls engaged in a greater percentage of their total MVPA together with their parent than boys. Girls and older children engaged in more sedentary behavior together with their parent than boys and younger children. Older parents engaged in a greater percentage of their sedentary behavior together with their children than younger parents. CONCLUSIONS: Replacing the time that parents and children spend together in sedentary pursuits with joint physical activity could have health benefits, especially for girls, older children, older parents, and higher income families.