Table 4

Average output power (mW) and percentage maximum power by call characteristics and phone use circumstances

900 MHz1800 MHzPMax (%)
Mean (SD) power*Regression coefficient (95% CI)†Mean (SD) powerRegression coefficient (95% CI)Mean (SD), %Regression coefficient (95% CI)
Duration of callNo of calls
    >60 s27789128.2 (87.8)62.7 (43.7)36.1 (37.9)
    30–60 s13265133.1 (91.2)0.9 (−1.0 to 2.8)63.8 (45.9)0.2 (−1.1 to 1.4)38.2 (40.0)0.8 (0.1 to 1.6)
    10–30 s13805134.6 (94.4)5.5 (3.6 to 7.4)63.3 (46.0)1.1 (−0.2 to 2.3)39.2 (41.0)3.0 (2.3 to 3.7)
    5–10 s3961141.8 (98.2)13.3 (10.1 to 16.6)70.8 (48.3)9.2 (7.1 to 11.3)44.5 (43.3)8.5 (7.3 to 9.7)
    <5 s4331159.1 (101.5)27.8 (24.7 to 30.9)76.4 (52.4)14.3 (12.1 to 16.4)53.8 (47.0)16.5 (15.3 to 17.6)
Time of day
    Night (23 h–8 h)3649140.7 (91.4)63.3 (45.8)41.5 (40.9)
    Day (8 h–19 h)48192132.2 (91.3)−5.1 (−8.3 to −1.8)63.9 (45.3)1.1 (−1.1 to 3.2)38.2 (40.0)−2.4 (−3.6 to −1.1)
    Evening (19 h–23 h)11250135.2 (93.4)0.1 (−3.5 to 3.7)65.6 (46.3)2.7 (0.3 to 5.1)41.4 (41.3)0.3 (−1.1 to 1.7)
Use of phone in urban/rural location
No of subjects
    Mainly urban393129.0 (92.1)61.8 (45.6)37.2 (40.0)
    Mainly rural34138.4 (93.6)17.3 (4.0 to 30.6)63.4 (43.2)7.9 (−1.1 to 17.0)43.5 (41.6)8.2 (2.3 to 14.0)
    Both urban and rural64155.1 (85.2)3.9 (−6.8 to 14.5)80.4 (42.2)7.9 (1.9 to 13.9)48.2 (40.0)2.7 (−1.6 to 7.0)
Use of phone while moving in vehicle
    Never182139.4 (91.7)70.5 (45.9)41.8 (41.3)
    Less than half172136.1 (90.4)−5.0 (−13.1 to 3.2)63.6 (44.9)−2.6 (−7.3 to 2.0)39.3 (39.9)−3.5 (−6.9 to −0.1)
    About half56124.5 (92.1)0.8 (−11.4 to 13.1)64.2 (44.6)−3.3 (−9.7 to 3.1)36.8 (39.6)−2.0 (−6.8 to 2.8)
    More than half28119.4 (89.7)−6.0 (−21.7 to 9.8)55.4 (42.3)−4.8 (−13.2 to 3.6)35.8 (38.5)−3.4 (−9.7 to 2.9)
    Nearly always7161.6 (82.6)15.5 (−18.8 to 49.7)61.1 (43.7)−0.5 (−15.8 to 14.8)44.4 (39.6)2.5 (−9.5 to 14.4)
Use of phone inside buildings§
    Never19133.6 (80.2)59.2 (41.6)33.2 (36.0)
    Less than half58123.7 (90.7)−7.2 (−27.8 to 13.4)60.5 (44.4)2.5 (−8.2 to 13.2)36.0 (39.6)1.0 (−7.4 to 9.3)
    About half81146.1 (88.0)−2.6 (−22.6 to 17.3)69.8 (45.3)2.2 (−8.1 to 12.5)41.6 (40.4)1.2 (−6.8 to 9.3)
    More than half88125.5 (92.0)−11.3 (−31.5 to 8.8)59.2 (45.8)1.5 (−9.0 to 12.1)36.9 (39.9)−1.7 (−9.9 to 6.6)
    Nearly always60120.8 (94.0)−9.8 (−30.5 to 11.0)65.3 (46.3)2.3 (−8.7 to 13.2)36.8 (40.3)0.01 (−8.5 to 8.5)
  • *Unadjusted power level. †Regression coefficient for difference in output power (in mW) between specified category and the comparison category (–); from linear regression model adjusted for operator, call duration and software-modified phone model. ‡Not included in the questionnaire in Sweden. §Only included in questionnaires in later part of the study: not in Denmark, France, Germany, Sweden or UK North 1.

  • PMax, maximum power.