However, the case crossover design is only appropriate to investigate the effects of incidental exposures on the event of interest and, therefore, is not suitable to estimate the risk in people exposed to long-term treatments [ 7, 15, 16].
Therefore, here we report only results for exposure to PM10 on the event day compared with temperature-matched control days.
In this method, the exposure on the date of an event (case) is compared with several nonevent control days (referent periods) occurring on the same month and year.
4. Temporal relationship: exposure precedes the event.
In these analyses, we defined the hazard period as 1, 2, or 3 days before the day of death (lag days 1, 2, and 3, respectively) or as the moving-average exposure on 2 (event day and lag day 1) or 3 (event day and lag days 1 and 2) consecutive days.
Exposure was characterised for each health event using the nearest monitoring station to the place of residence, with the condition that exposure information was not missing on the event day and on ≥90% of days within each risk period (as defined in the analysis section).
We also tested a possible effect of increasing exposure to insulin, sulfonylureas and metformin on the event rates for cancer.
We used the following criteria to select relevant mercury releases (exposure events): First, the event had to be reported between 2002 and 2007, a time frame that represents the most current information available on exposure events.
Our objective was to assess the potential impact of long-term PM2.5 exposure on event time, defined as time to first admission for dementia, Alzheimer's (AD), or Parkinson's (PD) diseases in an elderly population across the northeastern United States.
In contrast, anemia status did not change the influence of air pollution exposure on ARI events that required consultation with a physician (Table 4).
