<p>In some neighbourhoods, 19 per cent — nearly 1 in 5 — of children have asthma, while in others the rate can be as low as 3 per cent. Heavy traffic, industrial incinerators, and other outdoor air pollution sources have all been blamed in the past.<br /><br />But researchers at Columbia University have now found that children living in neighbourhoods with high rates of asthma were twice as likely to carry antibodies against a cockroach protein in their blood, a sign the children had been exposed to the insects and were likely allergic to them.<br /><br />In addition, homes in the neighbourhoods with high rates of asthma contained more of the allergen produced by cockroaches in household dust.</p>
<p>In some neighbourhoods, 19 per cent — nearly 1 in 5 — of children have asthma, while in others the rate can be as low as 3 per cent. Heavy traffic, industrial incinerators, and other outdoor air pollution sources have all been blamed in the past.<br /><br />But researchers at Columbia University have now found that children living in neighbourhoods with high rates of asthma were twice as likely to carry antibodies against a cockroach protein in their blood, a sign the children had been exposed to the insects and were likely allergic to them.<br /><br />In addition, homes in the neighbourhoods with high rates of asthma contained more of the allergen produced by cockroaches in household dust.</p>