Recorded presentation

Stanley H. Weiss, MD, Epidemiology, UMDNJ - New Jersey Medical School & NJ School of Public Health, 30 Bergen St, Bldg 16, Suite ADMC 1614, Newark, NJ 07107-3000, Azadeh Tasslimi, BA, Dept. Preventive Medicine & Community Health / Epidemiology, UMDNJ - New Jersey Medical School, 30 Bergen St, Bldg 16, Suite ADMC 1614, Newark, NJ 07107-3000, 973 972-7721, tassliaz@UMDNJ.EDU, Amy L. Davidow, PhD, Department Preventive Medicine and Community Health, UMDNJ-New Jersey Medical School, 185 South Orange Ave, Newark, NJ 07103-2714, and Clifford P. Weisel, PhD, Environmental and Occupational Health Sciences Institute, UMDNJ - EOHSI /Robert Wood Johnson Medical School & NJ School of Public Health, 170 Frelinghuysen Road, EOSHI 3-314, Piscataway, NJ 08855.

In spring 2003, a prospective study in northwestern NJ was conducted. Participants recorded daily symptoms, medication use, exposures and PEFR via Internet with ongoing monitoring. Average hourly air concentrations of SO₂ were determined. 27 (59% female) students, ages 9-17 years (mean=12.9), participated; mean study participation 115 days. PEFR recorded 88% of participant-days (2205/3098). Mean PEFR 346LPM (range=200-710).

A linear mixed-effects model with longitudinal data and random intercept was used (SAS-ProcMIXED). The outcome measure was logarithm(ln) of PEFR. Model building included stepwise assessments of effects of peak (maximum hourly mean) and mean SO₂ (linear, quadratic, cubic terms using orthogonal polynomials), peak and mean 1- and 2-day lagged SO₂, mean daytime (7AM-6PM) temperature, age, gender, and same-day medication use.

Controlling for daytime temperature and same-day medication use, there is an inverse relationship between ln(PEFR) and peak same-day SO₂ and mean prior-day SO₂. The effect of prior-day mean SO₂ is roughly 10-fold the effect of peak same-day SO₂ value (coefficients -0.00112 vs. –0.00015), controlling for temperature and medication use. Increase of 10 parts per billion (ppb) in mean prior-day SO₂ reduced PEFR 1.2%. 10ppb increase in peak same-day SO₂ reduced PEFR 0.15%. Daily mean and peak SO₂ ranged up to 21ppb and 131ppb, respectively. The model would predict 4% change in PEFR across entire population for this range. Prior-day mean SO₂ values ranged up to 20.5ppb, just 15% of national mandated 24-hour toxicity standard (140ppb). Thus, the effect observed is far below current environmental standards. Further analyses including additional environmental measures are ongoing.

Learning Objectives:

• At the end of this session, the participant will be able to apply statistical models to better understand how a percent change in SO2 is associated with a percent change in peak expiratory flow rate, differentiate between the acute and lagged effects of 'moderate' levels of SO2 on peak expiratory flow rate of asthmatics, and discuss the implications of current air pollution standards on the health of sensitive populations such as asthmatic children.

Keywords: Asthma, Air Pollutants

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.

Recorded presentation