Author's reply.

Sir

This is a response to the queries raised in a Letter to the Editor[1] concerning the article titled, ‘The relationship between lung function and indoor air pollution among rural women in the Niger Delta region of Nigeria.’ The authors of the letter raised four issues: (1) There are other publications[12] by Umoh et al., focusing on the problem of chronic bronchitis in the same community and same period in the Niger delta; (2) Umoh et al. mentioned no further relationship between exposure to smoke and anxiety;[2] (3) there is a discrepancy in the number of patients with chronic bronchitis in the two reports;[12] and (4) whether there is any other pollution in this area in addition to fish smoking.

The studies were carried out at about the same time, within the same community, by the same investigators. Therefore, the three reports came from the same population. In the article referenced as 1,[2] a sample of both males and females were used, while the other two involved only the female population. The index report focused on lung function and exposure. The article referenced as 1[2] focused on respiratory symptoms, while the article referenced as 2[3] focused on the psychological consequences of indoor air pollution.

In the article referenced as 2[3] the authors did mention the relationship between exposure and anxiety in the results section, as well as in the discussion.

Although the reports came from the same population there were slight differences in the samples. The psychiatrists were not satisfied with some responses and those were removed from the analysis and more subjects were subsequently recruited to make up the numbers.[23]

The study area is a fishing settlement in the Niger delta region of Nigeria. This report evaluated the relationship between biomass smoke and lung function. Other sources of indoor air pollution were not recorded and the authors assumed that the influence of these would not be selective. The only other possible source of outdoor air pollution would have come from gas flaring during crude oil exploration. Although crude oil exploration occurred in the Niger Delta area of Nigeria, the exact locations of these oil wells were far from the study area, thus the authors did not consider that as a factor. Moreover, as the effects of such pollution would not be selective it was unlikely to introduce any bias in the analysis.