Nitrogen Dioxide pollution and hazardous household environment: What impacts more congenital malformations

•We show that only the minor malformations are associated with exposure to NO2.•Major malformations are associated with hazardous exposures in a household.•Exposure to close hazardous environment has a more profound impact on health.

Nitrogen Dioxide (NO2) is a product of fuel combustion originating mainly from industry and transportation. Studies suggest an association between NO2 and congenital malformations (CM). We investigated an independent effect of NO2 on CM by adjusting to individual factors and household environment in 1024 Bedouin-Arab pregnant women in southern Israel. This population is characterised by high rates of CMs, frequent consanguineous marriages, paternal smoking, temporary housing and usage of open fire for heat cooking.Information on household risk factors was collected during an interview. Ambient measurements of 24-h average NO2 and meteorological conditions were obtained from 13 local monitors.Median value of daily NO2 measured in the area was 6.78 ppb. CM was diagnosed in 8.0% (82) of offspring. Maternal NO2 exposure during the 1st trimester >8.6 ppb was significantly associated with minor CM (RR = 2.68, p = 0.029). Major CM were independently associated with maternal juvenile diabetes (RR = 9.97, p-value = 0.002) and heating by open fire (RR = 2.00, p-value = 0.049), but not NO2 exposure.We found that NO2 emissions had an independent impact only on minor malformations, whereas major malformations depended mostly on the household environment. Antepartum deaths were associated by maternal morbidity.