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Radon gas is the main natural source of exposure of the population to ionizing rays. Because of its impact on the health, this radioactive gas has become a great concern worldwide. In this study, radon concentrations in the air of some dwellings in Yopougon, one of the commune with the highest population rate of the district of Abidjan (Cote d’Ivoire), are reported using Solid State Nuclear Tracks Detectors (SSNTD) LR 115 type 2. The concentration values found vary from 26.3 to 173.3 Bq.m −3 with an average of 93.04 Bq.m −3 . This mean value is inferior to the world minimum level (100 Bq.m −3 ). The corresponding annual effective doses obtained vary from 0.66 to 4.37 mSv.y −1 . The mean value calculated which is 2.35 mSv.y −1 is higher than the action level (1 mSv.y −1 ) prescribed by ICRP 103, and also to the limits recommended by the WHO and the International Research on Cancer Center (IRCC). In this view, the Excess lung Cancer Risk (ECR) for the population living in the commune of Yopougon is evaluated. The values of ECR found associated to the average radon concentration are between 46 and 204 according to EPA and UNSCEAR standards.

The contribution of higher-twist mechanisms to π+ π−,K+K− and ρ° ρ° production in high-energy\(\bar p\)p collisions, with the two mesons emitted back to back at 90° in the c.m. frame and at moderate or largepT, has been calculated and compared with the minimal-twist contribution, i.e. double jet fragmentation. The signal/background ratio is shown to depend critically on Δp, a parameter defining the upper limit for non-detection of accompanying particles; and, to a lesser extent, on the meson wave function. It is shown that, while there is little hope for checking higher-twist contributions in pion pair production, such contributions may show up clearly in kaon and rho pair production. In the last case, it may be possible to use polarization effects, in addition to cross-section measurements, in order to show the occurrence of higher-twist mechanisms.