Nitrogen dioxide exposure, health outcomes, and associated demographic disparities due to gas and propane combustion by U.S. stoves.

Gas and propane stoves emit nitrogen dioxide (NO2) pollution indoors, but the exposures of different U.S. demographic groups are unknown. We estimate NO2 exposure and health consequences using emissions and concentration measurements from >100 homes, a room-specific indoor air quality model, epidemiological risk parameters, and statistical sampling of housing characteristics and occupant behavior. Gas and propane stoves increase long-term NO2 exposure 4.0 parts per billion volume on average across the United States, 75% of the World Health Organization's exposure guideline. This increased exposure likely causes ~50,000 cases of current pediatric asthma from long-term NO2 exposure alone. Short-term NO2 exposure from typical gas stove use frequently exceeds both World Health Organization and U.S. Environmental Protection Agency benchmarks. People living in residences <800 ft2 in size incur four times more long-term NO2 exposure than people in residences >3000 ft2 in size; American Indian/Alaska Native and Black and Hispanic/Latino households incur 60 and 20% more NO2 exposure, respectively, than the national average.

El incremento gradual de CO2 en la primera mitad de la incubación, con cambio posterior de la presión de O2, modifica la trayectoria de incubación del pollo de engorda / Gradual increase of CO2 during first stages of incubation with late change of O2 partial pressure, modifies the hatch trajectory of broiler chicks

This work was conducted to determine the effect of non-ventilation (NV) during the first 10 days of incubation on carbon dioxide (CO2) concentrations and its effects on embryonic development (ED). Two studies were done on fertile hatching eggs from breeder hens (Ross 308) of 30 and 45 weeks of age. In the first study, two different incubation conditions were created, one incubator was non-ventilated (NV) during the first ten days of incubation, allowing the CO2 to rise and a second incubator was kept under standard conditions, with adequate ventilation (V). After the first 10 days, both incubations were kept under standard conditions. NV group at 10 days of incubation showed 11 600 ppm of [CO2], with 48% of hatchability from fertile eggs, higher (P < 0.05) than 2 100 ppm of [CO2], and 41% of hatchability from fertile eggs of V group. Day-old chicks from NV were longer and heavier tan chicks from V group. For the second study, two different incubation conditions were created, one incubator was moderately non-ventilated (MNV), and the second one was strictly non-ventilated (SNV). At transfer time, a hole of 1.3 mm in diameter was done over eggshell air cell, every incubator had two groups: with hole (H) and without hole (NH). MNV group at ten days of incubation showed 15 000 ppm of [CO2], and SNV group showed 17 000 ppm of [CO2], with 82% and 77% of hatchability, respectively. The induced hypercapnia during the early development stage improved hatchability parameters, weight and length of chicks. In 45 week-old breeder hens, an optimal hatching profile at high height above sea level with a limit of 15 000 ppm of [CO2] was determined. The eggshell hole helps to reduce embryonic mortality at 19.8 days; however, under this type of NV incubation, it is very important to take into account egg-mass loss, height above sea level and eggshell conductance constant, since all these factors contribute to generate the optimal partial pressure of [O2] and [CO2] before and during hatching.

Se implementó ventilación restringida (VR) para obtener un aumento gradual de CO2 durante los primeros 10 días del desarrollo embrionario (DE) en dos estudios con huevos fértiles de aves reproductoras pesadas (Ross 308) de 30 y 45 semanas de edad. En el primer estudio se formaron dos grupos: VR y ventilación estándar (V). El grupo VR al día 10 del DE mostró 11 600 ppm de [CO2], con 48% de incubabilidad, mayor a las 2 100 ppm de CO2 y 41% de incubabilidad del grupo V. Los pollitos del grupo VR fueron más largos y pesados. En el segundo estudio, los grupos fueron: ventilación restringida media (VRM) y ventilación restringida alta (VRA). Al momento de la transferencia se efectuó una perforación de 1.3 mm en la cámara de aire, los grupos se subdividieron en cascarón sin perforar (CSP) y cascarón perforado (CP). El grupo VRM mostró 15 000 ppm de [CO2] y el VRA 17 000 ppm, con 82% y 77% de incubabilidad, respectivamente. La hipercapnia inducida en la etapa temprana del DE favorece los parámetros de incubación, el peso y la longitud de los pollitos. En gallinas de 45 semanas de edad se determinó un perfil óptimo de incubación a gran altitud sobre el nivel del mar, con límite de 15 000 ppm para [CO2]. La perforación en el cascarón disminuye la mortalidad en la etapa de inicio de la respiración pulmonar; sin embargo, debe lograrse el equilibrio hídrico de los embriones, además de considerar la altitud sobre el nivel del mar y el grado de k = conductancia del cascarón, ya que estos factores son clave para una óptima presión parcial de [O2] y [CO2] antes y durante la eclosión.