The immunological impact of traffic-related air pollution in an Iraqi population; a prospective cross-sectional study

Iraqi automobiles use some of the poorest quality fuel in the world, characterized by extremely high sulfur content. In this study, we aim to investigate the immunological impact of traffic-related air pollution (TRAP) on individuals residing in the Kurdistan Region of Iraq.

This prospective cross-sectional study (June 2021 and January 2022) assessed the immunological profile of 77 male participants in Sulaymaniyah Governorate who were grouped based on predefined exposure zones; High TRAP Group (n = 46) from urban areas with high exposure to TRAP and Low TRAP Group (n = 31) from rural areas with low exposure. An Aeroqual Series 500 monitor was used to estimate 24-hour arithmetic mean concentrations of PM1.0, PM2.5, and PM10 in the two exposure zones.

Age distribution was comparable between the groups. Participants of High TRAP Group had significantly lower total lymphocyte counts (1.09 ± 0.36 vs. 1.90 ± 0.41, p < 0.001), T-cell (601.41 ± 60.02 vs. 799.80 ± 56.04; p < 0.001), B-cell levels (113.05 ± 48.23 vs. 230.68 ± 57.90; p < 0.001), IgG (11.94 ± 2.52 vs. 13.35 ± 2.77; p = 0.024), and IgM levels (0.96 ± 0.40 vs. 1.4 ± 0.66, p < 0.001) compared to Low TRAP Group. No significant differences were found in total WBC, granulocytes, or IgA levels (p > 0.05). The presence of inflammatory diseases (mostly thyroiditis) was significantly more common among the individuals of High TRAP Group (13, 28.26% vs. 3, 9.68%; p = 0.048).

Individuals with high exposure to TRAP are associated with significant reductions in lymphocyte count, IgM and IgG levels.