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Estimate total daily exposure to an air pollutant

total_exposure.Rd

Estimates an individual's total daily exposure to an air pollutant by combining exposure during trips, exposure at destinations, and exposure at the home location. Travel routes are obtained from the TomTom Routing API, while pollutant concentrations are extracted from hourly grid shapefiles.

Usage

total_exposure(
  travel_list,
  mode,
  dir,
  key,
  selection,
  output_exp,
  departure_time_home,
  activity_minutes,
  pollutant,
  shapeValue,
  gridID,
  units
)

Arguments

travel_list

Data frame containing the sequence of locations visited during the day. It must contain latitude and longitude columns. The first location is assumed to be the home location and the final trip always returns to this point.

mode

Character vector indicating the travel mode for each trip (for example "car", "pedestrian" or "bicycle").

dir

Character. Working directory containing the pollutant grids and temporary files.

key

Character. TomTom API key.

selection

Integer or character vector indicating which alternative route is selected for each trip.

output_exp

Character. Output type. One of "df", "plot" or "polyline".

departure_time_home

Character. Departure date and time from the home location.

activity_minutes

Numeric vector indicating the duration (minutes) of the activity performed at each destination.

pollutant

Character. Pollutant name used for map classification (for example "PM2.5").

shapeValue

Character. Name of the pollutant concentration field in the grid shapefiles.

gridID

Character. Name of the grid identifier field.

units

Character. Pollutant concentration units displayed in the map.

Value

Depending on output_exp:

"df"

A data frame summarizing exposure for each trip and the total daily exposure.

"plot"

An interactive leaflet map showing the selected routes, visited locations and pollutant concentrations.

"polyline"

An sf object containing the route polylines.

Details

The function performs the following steps:

  • Retrieves alternative routes between consecutive locations using the TomTom Routing API.

  • Selects one route for each trip according to selection.

  • Estimates exposure during travel using the selected route.

  • Estimates exposure while remaining at each destination.

  • Estimates exposure at the home location before the first trip.

  • Calculates total daily exposure.

  • Optionally returns an interactive map showing routes and pollutant concentrations.

This function relies on the helper functions alternative_trajectories(), temporary_grid_search(), points_to_line(), map_colors(), and function_hours().

Examples

if (FALSE) { # \dontrun{
exposure <- total_exposure(
  travel_list = travel_list,
  mode = c("car", "pedestrian"),
  dir = data_dir,
  key = api_key,
  selection = c(1, 1),
  output_exp = "plot",
  departure_time_home = "2019-08-01 08:00:00",
  activity_minutes = c(480),
  pollutant = "PM2.5",
  shapeValue = "value",
  gridID = "ID",
  units = expression(mu * g/m^3)
)
} # }