<P> The combustion products of solid fuel in developing countries can cause many adverse health issues in people . Because a majority of pregnant women in developing countries, where rate of LBW is high, are heavily exposed to indoor air pollution, increased relative risk translates into substantial population attributable risk of 21% of LBW . </P> <P> One environmental exposure which has been found to increase the risk of low birth weight is particulate matter, a component of ambient air pollution . Because particulate matter is composed of extremely small particles, even nonvisible levels can be inhaled and present harm to the fetus . Particulate matter exposure can cause inflammation, oxidative stress, endocrine disruption, and impaired oxygen transport access to the placenta, all of which are mechanisms for heightening the risk of low birth weight . To reduce exposure to particulate matter, pregnant women can monitor the EPA's Air Quality Index and take personal precautionary measures such as reducing outdoor activity on low quality days, avoiding high - traffic roads / intersections, and / or wearing personal protective equipment (i.e., facial mask of industrial design). Indoor exposure to particulate matter can also be reduced through adequate ventilation, as well as use of clean heating and cooking methods . </P> <P> A correlation between maternal exposure to CO and low birth weight has been reported that the effect on birth weight of increased ambient CO was as large as the effect of the mother smoking a pack of cigarettes per day during pregnancy . It has been revealed that adverse reproductive effects (e.g., risk for LBW) were correlated with maternal exposure to air pollution combustion emissions in Eastern Europe and North America . Mercury is a known toxic heavy metal that can harm fetal growth and health, and there has been evidence showing that exposure to mercury (via consumption of large oily fish) during pregnancy may be related to higher risks of LBW in the offspring . </P> <P> It was revealed that, exposure of pregnant women to airplane noise was found to be associated with low birth weight . Aircraft noise exposure caused adverse effects on fetal growth leading to low birth weight and preterm infants . </P>

Which of the following is the standard classification for a low-birth weight infant