Do Weather Variables Predict Physical Activity in Baltimore Teens?

BACKGROUND: Environmental barriers to physical activity (PA) have been reported previously; however most have focused on physical or structural factors, and few have focused on weather. METHODS: Data from 331 predominately urban, African American (70%) teenaged students from the Baltimore Active Living Teens Study (BALTS) were analyzed to determine whether daily weather characteristics including temperature, precipitation, air quality index (AQI), and number of daylight hours were associated with PA as measured by an accelerometer. Weather data, obtained from a variety of sources, was merged with physical activity measurement days to match PA measurement days (between January and May, 2006) with weather variables for the same days. Linear regression was used. RESULTS: Mean daily temperature and precipitation were significantly associated with weekly moderate and vigorous PA. After adjusting for age, race, gender, and mother's education, for every 10 degree Fahrenheit increase, average daily moderate physical activity (MPA) increased by 2.5 minutes (95%CI: 0.5, 4.6). Days with precipitation had an average of 0.30 fewer minutes of vigorous physical activity (VPA) (95%CI: 0.03, 0.56) compared to days without precipitation. Average daily MPA was greater by 3.6 minutes (95%CI: 1.6, 5.7) on days with an unhealthy AQI than days with a healthy AQI. There were no significant associations between hours of daylight and PA. Daily temperature was a stronger predictor for females, but precipitation was a stronger predictor for males. CONCLUSIONS: Weather, particularly temperature, was associated with adolescents' PA, which demonstrates a need for indoor facilities and activities to promote PA in inclement weather.