根據全國性采集樣本的研究發現，暴露于灰塵中的內毒素是哮喘的一個危險因素。研究人員從5個不同地區室內采集的2,552個家庭灰塵樣本，包括臥室地板、被褥、家庭房間地板、沙發表面和廚房地板。

作者發現在哮喘、哮喘藥物和喘息與臥室地板和被褥灰塵水平之間存在強烈的相關性。盡管內毒素濃度在廚房和起居室地板灰塵中最高，而在被褥中最低(包括床墊和枕頭)。但是這些效應只在成人中觀察到，而在兒童中則沒有觀察到。

沒有觀察到過敏狀態對內毒素和哮喘預后之間關系有何影響。這就提示當前的內毒素暴露對過敏狀態影響很小，而氣管炎癥對內毒素暴露橫斷面人群影響最為顯著。這項研究發表在2005年12月第一期的《美國呼吸和重癥監護醫學》之上。

內毒素是特定革蘭氏陰性細菌外膜的毒性物質。這些分子與細菌細胞壁相結合，當細菌破裂或者分裂的時候釋放出來。

Endotoxins in House Dust Linked to Asthma
 
Exposure to household endotoxins in dust poses a significant risk for asthma, according to the first nationwide sampling of house dust. The investigators took 2,552 house dust samples from five locations within the home, including bedroom floors, bedding, family room floors, sofa surfaces, and kitchen floors.

The authors found that the strongest relationship between asthma, asthma medications, and wheezing came from endotoxin levels in bedroom floor and bedding dust. This was true despite the fact that endotoxin concentrations were highest in kitchen and living room floor dust, and lowest for bedding (including mattress and pillow). However, the effects were observed only in adults and not in children.

No effect was observed of allergy status on the relationship between endotoxin and asthma outcomes. This suggests that current endotoxin exposure may have little impact on allergy status and that airway inflammation is the most significant effect of endotoxin exposure in a cross-section of the population. The study appeared in the first issue for December 2005 of the American Journal of Respiratory and Critical Care Medicine.

Endotoxins are toxic substances associated with the outer membrane of certain Gram-negative bacteria. These molecules are bound to the bacterial cell wall and are released when the bacterium ruptures or disintegrates.